http://www.mongodb.org: The MongoDB Java Driver uber-artifact, containing the legacy driver, the mongodb-driver, mongodb-driver-core, and bson
  • Various (MongoDB) 
/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.mongodb.client.model;

import com.mongodb.MongoNamespace;
import com.mongodb.lang.Nullable;
import org.bson.BsonBoolean;
import org.bson.BsonDocument;
import org.bson.BsonDocumentWriter;
import org.bson.BsonInt32;
import org.bson.BsonString;
import org.bson.BsonValue;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.conversions.Bson;

import java.util.List;

import static java.util.Arrays.asList;
import static org.bson.assertions.Assertions.notNull;


Builders for aggregation pipeline stages.

@mongodb.driver.manualcore/aggregation-pipeline/ Aggregation pipeline
@mongodb.server.release2.2
Since:3.1
/**
 * Builders for aggregation pipeline stages.
 *
 * @mongodb.driver.manual core/aggregation-pipeline/ Aggregation pipeline
 * @mongodb.server.release 2.2
 * @since 3.1
 */
public final class Aggregates {

    
Creates an $addFields pipeline stage

Params:
  • fields –        the fields to add
Returns:the $addFields pipeline stage
@mongodb.driver.manualreference/operator/aggregation/addFields/ $addFields
@mongodb.server.release3.4
Since:3.4
/**
     * Creates an $addFields pipeline stage
     *
     * @param fields        the fields to add
     * @return the $addFields pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/addFields/ $addFields
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson addFields(final Field<?>... fields) {
        return addFields(asList(fields));
    }

    
Creates an $addFields pipeline stage

Params:
  • fields –        the fields to add
Returns:the $addFields pipeline stage
@mongodb.driver.manualreference/operator/aggregation/addFields/ $addFields
@mongodb.server.release3.4
Since:3.4
/**
     * Creates an $addFields pipeline stage
     *
     * @param fields        the fields to add
     * @return the $addFields pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/addFields/ $addFields
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson addFields(final List<Field<?>> fields) {
        return new AddFieldsStage(fields);
    }

    
Creates a $bucket pipeline stage

Params:
  • groupBy –       the criteria to group By
  • boundaries –    the boundaries of the buckets
Type parameters:
  • <TExpression> – the groupBy expression type
  • <Boundary> –    the boundary type
Returns:the $bucket pipeline stage
@mongodb.driver.manualreference/operator/aggregation/bucket/ $bucket
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $bucket pipeline stage
     *
     * @param <TExpression> the groupBy expression type
     * @param <Boundary>    the boundary type
     * @param groupBy       the criteria to group By
     * @param boundaries    the boundaries of the buckets
     * @return the $bucket pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/bucket/ $bucket
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression, Boundary> Bson bucket(final TExpression groupBy, final List<Boundary> boundaries) {
        return bucket(groupBy, boundaries, new BucketOptions());
    }

    
Creates a $bucket pipeline stage

Params:
  • groupBy –       the criteria to group By
  • boundaries –    the boundaries of the buckets
  • options –       the optional values for the $bucket stage
Type parameters:
  • <TExpression> – the groupBy expression type
  • <TBoundary> –    the boundary type
Returns:the $bucket pipeline stage
@mongodb.driver.manualreference/operator/aggregation/bucket/ $bucket
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $bucket pipeline stage
     *
     * @param <TExpression> the groupBy expression type
     * @param <TBoundary>    the boundary type
     * @param groupBy       the criteria to group By
     * @param boundaries    the boundaries of the buckets
     * @param options       the optional values for the $bucket stage
     * @return the $bucket pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/bucket/ $bucket
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression, TBoundary> Bson bucket(final TExpression groupBy, final List<TBoundary> boundaries,
                                                       final BucketOptions options) {
        return new BucketStage<TExpression, TBoundary>(groupBy, boundaries, options);
    }

    
Creates a $bucketAuto pipeline stage

Params:
  • groupBy –       the criteria to group By
  • buckets –       the number of the buckets
Type parameters:
  • <TExpression> – the groupBy expression type
Returns:the $bucketAuto pipeline stage
@mongodb.driver.manualreference/operator/aggregation/bucketAuto/ $bucketAuto
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $bucketAuto pipeline stage
     *
     * @param <TExpression> the groupBy expression type
     * @param groupBy       the criteria to group By
     * @param buckets       the number of the buckets
     * @return the $bucketAuto pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/bucketAuto/ $bucketAuto
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson bucketAuto(final TExpression groupBy, final int buckets) {
        return bucketAuto(groupBy, buckets, new BucketAutoOptions());
    }

    
Creates a $bucketAuto pipeline stage

Params:
  • groupBy –       the criteria to group By
  • buckets –       the number of the buckets
  • options –       the optional values for the $bucketAuto stage
Type parameters:
  • <TExpression> – the groupBy expression type
Returns:the $bucketAuto pipeline stage
@mongodb.driver.manualreference/operator/aggregation/bucketAuto/ $bucketAuto
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $bucketAuto pipeline stage
     *
     * @param <TExpression> the groupBy expression type
     * @param groupBy       the criteria to group By
     * @param buckets       the number of the buckets
     * @param options       the optional values for the $bucketAuto stage
     * @return the $bucketAuto pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/bucketAuto/ $bucketAuto
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson bucketAuto(final TExpression groupBy, final int buckets, final BucketAutoOptions options) {
        return new BucketAutoStage<TExpression>(groupBy, buckets, options);
    }

    
Creates a $count pipeline stage using the field name "count" to store the result

Returns:the $count pipeline stage
@mongodb.driver.manualreference/operator/aggregation/count/ $count
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $count pipeline stage using the field name "count" to store the result
     *
     * @return the $count pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/count/ $count
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson count() {
        return count("count");
    }

    
Creates a $count pipeline stage using the named field to store the result

Params:
  • field – the field in which to store the count
Returns:the $count pipeline stage
@mongodb.driver.manualreference/operator/aggregation/count/ $count
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $count pipeline stage using the named field to store the result
     *
     * @param field the field in which to store the count
     * @return the $count pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/count/ $count
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson count(final String field) {
        return new BsonDocument("$count", new BsonString(field));
    }

    
Creates a $match pipeline stage for the specified filter

Params:
  • filter – the filter to match
See Also:
Returns:the $match pipeline stage
@mongodb.driver.manualreference/operator/aggregation/match/ $match
/**
     * Creates a $match pipeline stage for the specified filter
     *
     * @param filter the filter to match
     * @return the $match pipeline stage
     * @see Filters
     * @mongodb.driver.manual reference/operator/aggregation/match/ $match
     */
    public static Bson match(final Bson filter) {
        return new SimplePipelineStage("$match", filter);
    }

    
Creates a $project pipeline stage for the specified projection

Params:
  • projection – the projection
See Also:
Returns:the $project pipeline stage
@mongodb.driver.manualreference/operator/aggregation/project/ $project
/**
     * Creates a $project pipeline stage for the specified projection
     *
     * @param projection the projection
     * @return the $project pipeline stage
     * @see Projections
     * @mongodb.driver.manual reference/operator/aggregation/project/ $project
     */
    public static Bson project(final Bson projection) {
        return new SimplePipelineStage("$project", projection);
    }

    
Creates a $sort pipeline stage for the specified sort specification

Params:
  • sort – the sort specification
See Also:
Returns:the $sort pipeline stage
@mongodb.driver.manualreference/operator/aggregation/sort/#sort-aggregation $sort
/**
     * Creates a $sort pipeline stage for the specified sort specification
     *
     * @param sort the sort specification
     * @return the $sort pipeline stage
     * @see Sorts
     * @mongodb.driver.manual reference/operator/aggregation/sort/#sort-aggregation $sort
     */
    public static Bson sort(final Bson sort) {
        return new SimplePipelineStage("$sort", sort);
    }

    
Creates a $sortByCount pipeline stage for the specified filter

Params:
  • filter –        the filter specification
Type parameters:
  • <TExpression> – the expression type
Returns:the $sortByCount pipeline stage
@mongodb.driver.manualreference/operator/aggregation/sortByCount/ $sortByCount
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $sortByCount pipeline stage for the specified filter
     *
     * @param <TExpression> the expression type
     * @param filter        the filter specification
     * @return the $sortByCount pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/sortByCount/ $sortByCount
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson sortByCount(final TExpression filter) {
        return new SortByCountStage<TExpression>(filter);
    }

    
Creates a $skip pipeline stage

Params:
  • skip – the number of documents to skip
Returns:the $skip pipeline stage
@mongodb.driver.manualreference/operator/aggregation/skip/ $skip
/**
     * Creates a $skip pipeline stage
     *
     * @param skip the number of documents to skip
     * @return the $skip pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/skip/ $skip
     */
    public static Bson skip(final int skip) {
        return new BsonDocument("$skip", new BsonInt32(skip));
    }

    
Creates a $limit pipeline stage for the specified filter

Params:
  • limit – the limit
Returns:the $limit pipeline stage
@mongodb.driver.manualreference/operator/aggregation/limit/  $limit
/**
     * Creates a $limit pipeline stage for the specified filter
     *
     * @param limit the limit
     * @return the $limit pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/limit/  $limit
     */
    public static Bson limit(final int limit) {
        return new BsonDocument("$limit", new BsonInt32(limit));
    }

    
Creates a $lookup pipeline stage, joining the current collection with the one specified in from
using equality match between the local field and the foreign field

Params:
  • from –         the name of the collection in the same database to perform the join with.
  • localField –   the field from the local collection to match values against.
  • foreignField – the field in the from collection to match values against.
  • as –           the name of the new array field to add to the input documents.
Returns:the $lookup pipeline stage
@mongodb.driver.manualreference/operator/aggregation/lookup/ $lookup
@mongodb.server.release3.2
Since:3.2
/**
     * Creates a $lookup pipeline stage, joining the current collection with the one specified in from
     * using equality match between the local field and the foreign field
     *
     * @param from         the name of the collection in the same database to perform the join with.
     * @param localField   the field from the local collection to match values against.
     * @param foreignField the field in the from collection to match values against.
     * @param as           the name of the new array field to add to the input documents.
     * @return the $lookup pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/lookup/ $lookup
     * @mongodb.server.release 3.2
     * @since 3.2
     */
    public static Bson lookup(final String from, final String localField, final String foreignField, final String as) {
        return new BsonDocument("$lookup", new BsonDocument("from", new BsonString(from))
                                                   .append("localField", new BsonString(localField))
                                                   .append("foreignField", new BsonString(foreignField))
                                                   .append("as", new BsonString(as)));
    }

    
Creates a $lookup pipeline stage, joining the current collection with the one specified in from using the given pipeline

Params:
  • from –          the name of the collection in the same database to perform the join with.
  • pipeline –      the pipeline to run on the joined collection.
  • as –            the name of the new array field to add to the input documents.
Returns:the $lookup pipeline stage
@mongodb.driver.manualreference/operator/aggregation/lookup/ $lookup
@mongodb.server.release3.6
Since:3.7
/**
     * Creates a $lookup pipeline stage, joining the current collection with the one specified in from using the given pipeline
     *
     * @param from          the name of the collection in the same database to perform the join with.
     * @param pipeline      the pipeline to run on the joined collection.
     * @param as            the name of the new array field to add to the input documents.
     * @return the $lookup pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/lookup/ $lookup
     * @mongodb.server.release 3.6
     * @since 3.7
     *
     */
    public static Bson lookup(final String from, final List<? extends Bson> pipeline, final String as) {
        return lookup(from, null, pipeline, as);
    }

    
Creates a $lookup pipeline stage, joining the current collection with the one specified in from using the given pipeline

Params:
  • from –          the name of the collection in the same database to perform the join with.
  • let –           the variables to use in the pipeline field stages.
  • pipeline –      the pipeline to run on the joined collection.
  • as –            the name of the new array field to add to the input documents.
Type parameters:
  • <TExpression> – the Variable value expression type
Returns:the $lookup pipeline stage
@mongodb.driver.manualreference/operator/aggregation/lookup/ $lookup
@mongodb.server.release3.6
Since:3.7
/**
     * Creates a $lookup pipeline stage, joining the current collection with the one specified in from using the given pipeline
     *
     * @param <TExpression> the Variable value expression type
     * @param from          the name of the collection in the same database to perform the join with.
     * @param let           the variables to use in the pipeline field stages.
     * @param pipeline      the pipeline to run on the joined collection.
     * @param as            the name of the new array field to add to the input documents.
     * @return the $lookup pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/lookup/ $lookup
     * @mongodb.server.release 3.6
     * @since 3.7
     */
    public static <TExpression> Bson lookup(final String from, @Nullable final List<Variable<TExpression>> let,
                                            final List<? extends Bson> pipeline, final String as) {
       return new LookupStage<TExpression>(from, let, pipeline, as);
    }

    
Creates a facet pipeline stage

Params:
  • facets – the facets to use
Returns:the new pipeline stage
@mongodb.driver.manualreference/operator/aggregation/facet/ $facet
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a facet pipeline stage
     *
     * @param facets the facets to use
     * @return the new pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/facet/ $facet
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson facet(final List<Facet> facets) {
        return new FacetStage(facets);
    }

    
Creates a facet pipeline stage

Params:
  • facets – the facets to use
Returns:the new pipeline stage
@mongodb.driver.manualreference/operator/aggregation/facet/ $facet
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a facet pipeline stage
     *
     * @param facets the facets to use
     * @return the new pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/facet/ $facet
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static Bson facet(final Facet... facets) {
        return new FacetStage(asList(facets));
    }

    
Creates a graphLookup pipeline stage for the specified filter

Params:
  • from –             the collection to query
  • startWith –        the expression to start the graph lookup with
  • connectFromField – the from field
  • connectToField –   the to field
  • as –               name of field in output document
Type parameters:
  • <TExpression> –     the expression type
Returns:the $graphLookup pipeline stage
@mongodb.driver.manualreference/operator/aggregation/graphLookup/ $graphLookup
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a graphLookup pipeline stage for the specified filter
     *
     * @param <TExpression>     the expression type
     * @param from             the collection to query
     * @param startWith        the expression to start the graph lookup with
     * @param connectFromField the from field
     * @param connectToField   the to field
     * @param as               name of field in output document
     * @return the $graphLookup pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/graphLookup/ $graphLookup
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson graphLookup(final String from, final TExpression startWith, final String connectFromField,
                                                 final String connectToField, final String as) {
        return graphLookup(from, startWith, connectFromField, connectToField, as, new GraphLookupOptions());
    }

    
Creates a graphLookup pipeline stage for the specified filter

Params:
  • from –             the collection to query
  • startWith –        the expression to start the graph lookup with
  • connectFromField – the from field
  • connectToField –   the to field
  • as –               name of field in output document
  • options –          optional values for the graphLookup
Type parameters:
  • <TExpression> –    the expression type
Returns:the $graphLookup pipeline stage
@mongodb.driver.manualreference/operator/aggregation/graphLookup/ $graphLookup
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a graphLookup pipeline stage for the specified filter
     *
     * @param <TExpression>    the expression type
     * @param from             the collection to query
     * @param startWith        the expression to start the graph lookup with
     * @param connectFromField the from field
     * @param connectToField   the to field
     * @param as               name of field in output document
     * @param options          optional values for the graphLookup
     * @return the $graphLookup pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/graphLookup/ $graphLookup
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson graphLookup(final String from, final TExpression startWith, final String connectFromField,
                                                 final String connectToField, final String as, final GraphLookupOptions options) {
        notNull("options", options);
        return new GraphLookupStage<TExpression>(from, startWith, connectFromField, connectToField, as, options);
    }

    
Creates a $group pipeline stage for the specified filter

Params:
  • id –                the id expression for the group, which may be null
  • fieldAccumulators – zero or more field accumulator pairs
Type parameters:
  • <TExpression> –     the expression type
Returns:the $group pipeline stage
@mongodb.driver.manualreference/operator/aggregation/group/ $group
@mongodb.driver.manualmeta/aggregation-quick-reference/#aggregation-expressions Expressions
/**
     * Creates a $group pipeline stage for the specified filter
     *
     * @param <TExpression>     the expression type
     * @param id                the id expression for the group, which may be null
     * @param fieldAccumulators zero or more field accumulator pairs
     * @return the $group pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/group/ $group
     * @mongodb.driver.manual meta/aggregation-quick-reference/#aggregation-expressions Expressions
     */
    public static <TExpression> Bson group(@Nullable final TExpression id, final BsonField... fieldAccumulators) {
        return group(id, asList(fieldAccumulators));
    }

    
Creates a $group pipeline stage for the specified filter

Params:
  • id –                the id expression for the group, which may be null
  • fieldAccumulators – zero or more field accumulator pairs
Type parameters:
  • <TExpression> –     the expression type
Returns:the $group pipeline stage
@mongodb.driver.manualreference/operator/aggregation/group/ $group
@mongodb.driver.manualmeta/aggregation-quick-reference/#aggregation-expressions Expressions
/**
     * Creates a $group pipeline stage for the specified filter
     *
     * @param <TExpression>     the expression type
     * @param id                the id expression for the group, which may be null
     * @param fieldAccumulators zero or more field accumulator pairs
     * @return the $group pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/group/ $group
     * @mongodb.driver.manual meta/aggregation-quick-reference/#aggregation-expressions Expressions
     */
    public static <TExpression> Bson group(@Nullable final TExpression id, final List<BsonField> fieldAccumulators) {
        return new GroupStage<TExpression>(id, fieldAccumulators);
    }

    
Creates a $unwind pipeline stage for the specified field name, which must be prefixed by a '$' sign. 
Params:
  • fieldName – the field name, prefixed by a '$' sign
Returns:the $unwind pipeline stage
@mongodb.driver.manualreference/operator/aggregation/unwind/ $unwind
/**
     * Creates a $unwind pipeline stage for the specified field name, which must be prefixed by a {@code '$'} sign.
     *
     * @param fieldName the field name, prefixed by a {@code '$' sign}
     * @return the $unwind pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/unwind/ $unwind
     */
    public static Bson unwind(final String fieldName) {
        return new BsonDocument("$unwind", new BsonString(fieldName));
    }

    
Creates a $unwind pipeline stage for the specified field name, which must be prefixed by a '$' sign. 
Params:
  • fieldName –  the field name, prefixed by a '$' sign
  • unwindOptions – options for the unwind pipeline stage
Returns:the $unwind pipeline stage
@mongodb.driver.manualreference/operator/aggregation/unwind/ $unwind
@mongodb.server.release3.2
Since:3.2
/**
     * Creates a $unwind pipeline stage for the specified field name, which must be prefixed by a {@code '$'} sign.
     *
     * @param fieldName     the field name, prefixed by a {@code '$' sign}
     * @param unwindOptions options for the unwind pipeline stage
     * @return the $unwind pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/unwind/ $unwind
     * @mongodb.server.release 3.2
     * @since 3.2
     */
    public static Bson unwind(final String fieldName, final UnwindOptions unwindOptions) {
        notNull("unwindOptions", unwindOptions);
        BsonDocument options = new BsonDocument("path", new BsonString(fieldName));
        Boolean preserveNullAndEmptyArrays = unwindOptions.isPreserveNullAndEmptyArrays();
        if (preserveNullAndEmptyArrays != null) {
            options.append("preserveNullAndEmptyArrays", BsonBoolean.valueOf(preserveNullAndEmptyArrays));
        }
        String includeArrayIndex = unwindOptions.getIncludeArrayIndex();
        if (includeArrayIndex != null) {
            options.append("includeArrayIndex", new BsonString(includeArrayIndex));
        }
        return new BsonDocument("$unwind", options);
    }

    
Creates a $out pipeline stage that writes into the specified collection

Params:
  • collectionName – the collection name
Returns:the $out pipeline stage
@mongodb.driver.manualreference/operator/aggregation/out/  $out
@mongodb.server.release2.6
/**
     * Creates a $out pipeline stage that writes into the specified collection
     *
     * @param collectionName the collection name
     * @return the $out pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/out/  $out
     * @mongodb.server.release 2.6
     */
    public static Bson out(final String collectionName) {
        return new BsonDocument("$out", new BsonString(collectionName));
    }

    
Creates a $merge pipeline stage that merges into the specified collection

Params:
  • collectionName – the name of the collection to merge into
Returns:the $merge pipeline stage
Since:3.11
@mongodb.driver.manualreference/operator/aggregation/merge/  $merge
@mongodb.server.release4.2
/**
     * Creates a $merge pipeline stage that merges into the specified collection
     *
     * @param collectionName the name of the collection to merge into
     * @return the $merge pipeline stage
     * @since 3.11
     * @mongodb.driver.manual reference/operator/aggregation/merge/  $merge
     * @mongodb.server.release 4.2
     */
    public static Bson merge(final String collectionName) {
        return merge(collectionName, new MergeOptions());
    }

    
Creates a $merge pipeline stage that merges into the specified namespace

Params:
  • namespace – the namespace to merge into
Returns:the $merge pipeline stage
Since:3.11
@mongodb.driver.manualreference/operator/aggregation/merge/  $merge
@mongodb.server.release4.2
/**
     * Creates a $merge pipeline stage that merges into the specified namespace
     *
     * @param namespace the namespace to merge into
     * @return the $merge pipeline stage
     * @since 3.11
     * @mongodb.driver.manual reference/operator/aggregation/merge/  $merge
     * @mongodb.server.release 4.2
     */
    public static Bson merge(final MongoNamespace namespace) {
        return merge(namespace, new MergeOptions());
    }

    
Creates a $merge pipeline stage that merges into the specified collection using the specified options.

Params:
  • collectionName – the name of the collection to merge into
  • options – the merge options
Returns:the $merge pipeline stage
Since:3.11
@mongodb.driver.manualreference/operator/aggregation/merge/  $merge
@mongodb.server.release4.2
/**
     * Creates a $merge pipeline stage that merges into the specified collection using the specified options.
     *
     * @param collectionName the name of the collection to merge into
     * @param options the merge options
     * @return the $merge pipeline stage
     * @since 3.11
     * @mongodb.driver.manual reference/operator/aggregation/merge/  $merge
     * @mongodb.server.release 4.2
     */
    public static Bson merge(final String collectionName, final MergeOptions options) {
        return new MergeStage(new BsonString(collectionName), options);
    }

    
Creates a $merge pipeline stage that merges into the specified namespace using the specified options.

Params:
  • namespace – the namespace to merge into
  • options – the merge options
Returns:the $merge pipeline stage
Since:3.11
@mongodb.driver.manualreference/operator/aggregation/merge/  $merge
@mongodb.server.release4.2
/**
     * Creates a $merge pipeline stage that merges into the specified namespace using the specified options.
     *
     * @param namespace the namespace to merge into
     * @param options the merge options
     * @return the $merge pipeline stage
     * @since 3.11
     * @mongodb.driver.manual reference/operator/aggregation/merge/  $merge
     * @mongodb.server.release 4.2
     */
    public static Bson merge(final MongoNamespace namespace, final MergeOptions options) {
        return new MergeStage(new BsonDocument("db", new BsonString(namespace.getDatabaseName()))
                .append("coll", new BsonString(namespace.getCollectionName())), options);
    }

    
Creates a $replaceRoot pipeline stage

Params:
  • value –         the new root value
Type parameters:
  • <TExpression> – the new root type
Returns:the $replaceRoot pipeline stage
@mongodb.driver.manualreference/operator/aggregation/replaceRoot/ $replaceRoot
@mongodb.server.release3.4
Since:3.4
/**
     * Creates a $replaceRoot pipeline stage
     *
     * @param <TExpression> the new root type
     * @param value         the new root value
     * @return the $replaceRoot pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/replaceRoot/ $replaceRoot
     * @mongodb.server.release 3.4
     * @since 3.4
     */
    public static <TExpression> Bson replaceRoot(final TExpression value) {
        return new ReplaceStage<TExpression>(value);
    }

    
Creates a $replaceRoot pipeline stage

With $replaceWith, you can promote an embedded document to the top-level.
You can also specify a new document as the replacement.


The $replaceWith is an alias for replaceRoot(Object).


Params:
  • value –         the new root value
Type parameters:
Returns:the $replaceRoot pipeline stage
@mongodb.driver.manualreference/operator/aggregation/replaceWith/ $replaceWith
@mongodb.server.release4.2
Since:3.11
/**
     * Creates a $replaceRoot pipeline stage
     *
     * <p>With $replaceWith, you can promote an embedded document to the top-level.
     * You can also specify a new document as the replacement.</p>
     *
     * <p>The $replaceWith is an alias for {@link #replaceRoot(Object)}.</p>
     *
     * @param <TExpression> the new root type
     * @param value         the new root value
     * @return the $replaceRoot pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/replaceWith/ $replaceWith
     * @mongodb.server.release 4.2
     * @since 3.11
     */
    public static <TExpression> Bson replaceWith(final TExpression value) {
        return new ReplaceStage<TExpression>(value, true);
    }

    
Creates a $sample pipeline stage with the specified sample size

Params:
  • size – the sample size
Returns:the $sample pipeline stage
@mongodb.driver.manualreference/operator/aggregation/sample/  $sample
@mongodb.server.release3.2
Since:3.2
/**
     * Creates a $sample pipeline stage with the specified sample size
     *
     * @param size the sample size
     * @return the $sample pipeline stage
     * @mongodb.driver.manual reference/operator/aggregation/sample/  $sample
     * @mongodb.server.release 3.2
     * @since 3.2
     */
    public static Bson sample(final int size) {
        return new BsonDocument("$sample", new BsonDocument("size", new BsonInt32(size)));
    }

    static void writeBucketOutput(final CodecRegistry codecRegistry, final BsonDocumentWriter writer,
                                  @Nullable final List<BsonField> output) {
        if (output != null) {
            writer.writeName("output");
            writer.writeStartDocument();
            for (BsonField field : output) {
                writer.writeName(field.getName());
                BuildersHelper.encodeValue(writer, field.getValue(), codecRegistry);
            }
            writer.writeEndDocument();
        }
    }

    private static class SimplePipelineStage implements Bson {
        private final String name;
        private final Bson value;

        SimplePipelineStage(final String name, final Bson value) {
            this.name = name;
            this.value = value;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> documentClass, final CodecRegistry codecRegistry) {
            return new BsonDocument(name, value.toBsonDocument(documentClass, codecRegistry));
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            SimplePipelineStage that = (SimplePipelineStage) o;

            if (name != null ? !name.equals(that.name) : that.name != null) {
                return false;
            }
            return value != null ? value.equals(that.value) : that.value == null;
        }

        @Override
        public int hashCode() {
            int result = name != null ? name.hashCode() : 0;
            result = 31 * result + (value != null ? value.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                           + "name='" + name + '\''
                           + ", value=" + value
                           + '}';
        }
    }

    private static final class BucketStage<TExpression, TBoundary> implements Bson {

        private final TExpression groupBy;
        private final List<TBoundary> boundaries;
        private final BucketOptions options;

        BucketStage(final TExpression groupBy, final List<TBoundary> boundaries, final BucketOptions options) {
            notNull("options", options);
            this.groupBy = groupBy;
            this.boundaries = boundaries;
            this.options = options;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeStartDocument("$bucket");

            writer.writeName("groupBy");
            BuildersHelper.encodeValue(writer, groupBy, codecRegistry);

            writer.writeStartArray("boundaries");
            for (TBoundary boundary : boundaries) {
                BuildersHelper.encodeValue(writer, boundary, codecRegistry);
            }
            writer.writeEndArray();
            Object defaultBucket = options.getDefaultBucket();
            if (defaultBucket != null) {
                writer.writeName("default");
                BuildersHelper.encodeValue(writer, defaultBucket, codecRegistry);
            }
            writeBucketOutput(codecRegistry, writer, options.getOutput());
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            BucketStage<?, ?> that = (BucketStage<?, ?>) o;

            if (groupBy != null ? !groupBy.equals(that.groupBy) : that.groupBy != null) {
                return false;
            }
            if (boundaries != null ? !boundaries.equals(that.boundaries) : that.boundaries != null) {
                return false;
            }
            return options.equals(that.options);
        }

        @Override
        public int hashCode() {
            int result = groupBy != null ? groupBy.hashCode() : 0;
            result = 31 * result + (boundaries != null ? boundaries.hashCode() : 0);
            result = 31 * result + options.hashCode();
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$bucket'"
                + ", boundaries=" + boundaries
                + ", groupBy=" + groupBy
                + ", options=" + options
                + '}';
        }
    }

    private static final class BucketAutoStage<TExpression> implements Bson {

        private final TExpression groupBy;
        private final int buckets;
        private final BucketAutoOptions options;

        BucketAutoStage(final TExpression groupBy, final int buckets, final BucketAutoOptions options) {
            notNull("options", options);
            this.groupBy = groupBy;
            this.buckets = buckets;
            this.options = options;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeStartDocument("$bucketAuto");

            writer.writeName("groupBy");
            BuildersHelper.encodeValue(writer, groupBy, codecRegistry);

            writer.writeInt32("buckets", buckets);

            writeBucketOutput(codecRegistry, writer, options.getOutput());

            BucketGranularity granularity = options.getGranularity();
            if (granularity != null) {
                writer.writeString("granularity", granularity.getValue());
            }
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            BucketAutoStage<?> that = (BucketAutoStage<?>) o;

            if (buckets != that.buckets) {
                return false;
            }
            if (groupBy != null ? !groupBy.equals(that.groupBy) : that.groupBy != null) {
                return false;
            }
            return options.equals(that.options);
        }

        @Override
        public int hashCode() {
            int result = groupBy != null ? groupBy.hashCode() : 0;
            result = 31 * result + buckets;
            result = 31 * result + options.hashCode();
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$bucketAuto'"
                + ", buckets=" + buckets
                + ", groupBy=" + groupBy
                + ", options=" + options
                + '}';
        }
    }

    private static final class LookupStage<TExpression> implements Bson {
        private final String from;
        private final List<Variable<TExpression>> let;
        private final List<? extends Bson> pipeline;
        private final String as;

        private LookupStage(final String from, @Nullable final List<Variable<TExpression>> let, final List<? extends Bson> pipeline,
                            final String as) {
            this.from = from;
            this.let = let;
            this.pipeline = pipeline;
            this.as = as;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeStartDocument("$lookup");

            writer.writeString("from", from);

            if (let != null) {
                writer.writeStartDocument("let");

                for (Variable<?> variable : let) {
                    writer.writeName(variable.getName());
                    BuildersHelper.encodeValue(writer, variable.getValue(), codecRegistry);
                }

                writer.writeEndDocument();
            }

            writer.writeName("pipeline");
            writer.writeStartArray();
            for (Bson stage : pipeline) {
                BuildersHelper.encodeValue(writer, stage, codecRegistry);
            }
            writer.writeEndArray();

            writer.writeString("as", as);

            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            LookupStage<?> that = (LookupStage<?>) o;

            if (from != null ? !from.equals(that.from) : that.from != null) {
                return false;
            }
            if (let != null ? !let.equals(that.let) : that.let != null) {
                return false;
            }
            if (pipeline != null ? !pipeline.equals(that.pipeline) : that.pipeline != null) {
                return false;
            }
            return as != null ? as.equals(that.as) : that.as == null;
        }

        @Override
        public int hashCode() {
            int result = from != null ? from.hashCode() : 0;
            result = 31 * result + (let != null ? let.hashCode() : 0);
            result = 31 * result + (pipeline != null ? pipeline.hashCode() : 0);
            result = 31 * result + (as != null ? as.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                    + "name='$lookup'"
                    + ", from='" + from + '\''
                    + ", let=" + let
                    + ", pipeline=" + pipeline
                    + ", as='" + as + '\''
                    + '}';
        }
    }

    private static final class GraphLookupStage<TExpression> implements Bson {
        private final String from;
        private final TExpression startWith;
        private final String connectFromField;
        private final String connectToField;
        private final String as;
        private final GraphLookupOptions options;

        private GraphLookupStage(final String from, final TExpression startWith, final String connectFromField, final String connectToField,
                                 final String as, final GraphLookupOptions options) {
            this.from = from;
            this.startWith = startWith;
            this.connectFromField = connectFromField;
            this.connectToField = connectToField;
            this.as = as;
            this.options = options;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeStartDocument("$graphLookup");

            writer.writeString("from", from);
            writer.writeName("startWith");
            BuildersHelper.encodeValue(writer, startWith, codecRegistry);

            writer.writeString("connectFromField", connectFromField);
            writer.writeString("connectToField", connectToField);
            writer.writeString("as", as);
            Integer maxDepth = options.getMaxDepth();
            if (maxDepth != null) {
                writer.writeInt32("maxDepth", maxDepth);
            }
            String depthField = options.getDepthField();
            if (depthField != null) {
                writer.writeString("depthField", depthField);
            }
            Bson restrictSearchWithMatch = options.getRestrictSearchWithMatch();
            if (restrictSearchWithMatch != null) {
                writer.writeName("restrictSearchWithMatch");
                BuildersHelper.encodeValue(writer, restrictSearchWithMatch, codecRegistry);
            }

            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            GraphLookupStage<?> that = (GraphLookupStage<?>) o;

            if (from != null ? !from.equals(that.from) : that.from != null) {
                return false;
            }
            if (startWith != null ? !startWith.equals(that.startWith) : that.startWith != null) {
                return false;
            }
            if (connectFromField != null ? !connectFromField.equals(that.connectFromField) : that.connectFromField != null) {
                return false;
            }
            if (connectToField != null ? !connectToField.equals(that.connectToField) : that.connectToField != null) {
                return false;
            }
            if (as != null ? !as.equals(that.as) : that.as != null) {
                return false;
            }
            return options != null ? options.equals(that.options) : that.options == null;
        }

        @Override
        public int hashCode() {
            int result = from != null ? from.hashCode() : 0;
            result = 31 * result + (startWith != null ? startWith.hashCode() : 0);
            result = 31 * result + (connectFromField != null ? connectFromField.hashCode() : 0);
            result = 31 * result + (connectToField != null ? connectToField.hashCode() : 0);
            result = 31 * result + (as != null ? as.hashCode() : 0);
            result = 31 * result + (options != null ? options.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$graphLookup'"
                + ", as='" + as + '\''
                + ", connectFromField='" + connectFromField + '\''
                + ", connectToField='" + connectToField + '\''
                + ", from='" + from + '\''
                + ", options=" + options
                + ", startWith=" + startWith
                + '}';
        }
    }

    private static class GroupStage<TExpression> implements Bson {
        private final TExpression id;
        private final List<BsonField> fieldAccumulators;

        GroupStage(final TExpression id, final List<BsonField> fieldAccumulators) {
            this.id = id;
            this.fieldAccumulators = fieldAccumulators;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeStartDocument("$group");

            writer.writeName("_id");
            BuildersHelper.encodeValue(writer, id, codecRegistry);

            for (BsonField fieldAccumulator : fieldAccumulators) {
                writer.writeName(fieldAccumulator.getName());
                BuildersHelper.encodeValue(writer, fieldAccumulator.getValue(), codecRegistry);
            }

            writer.writeEndDocument();
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            GroupStage<?> that = (GroupStage<?>) o;

            if (id != null ? !id.equals(that.id) : that.id != null) {
                return false;
            }
            return fieldAccumulators != null ? fieldAccumulators.equals(that.fieldAccumulators) : that.fieldAccumulators == null;
        }

        @Override
        public int hashCode() {
            int result = id != null ? id.hashCode() : 0;
            result = 31 * result + (fieldAccumulators != null ? fieldAccumulators.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                           + "name='$group'"
                           + ", id=" + id
                           + ", fieldAccumulators=" + fieldAccumulators
                           + '}';
        }
    }

    private static class SortByCountStage<TExpression> implements Bson {
        private final TExpression filter;

        SortByCountStage(final TExpression filter) {
            this.filter = filter;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());

            writer.writeStartDocument();

            writer.writeName("$sortByCount");
            BuildersHelper.encodeValue(writer, filter, codecRegistry);

            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            SortByCountStage<?> that = (SortByCountStage<?>) o;

            return filter != null ? filter.equals(that.filter) : that.filter == null;
        }

        @Override
        public int hashCode() {
            return filter != null ? filter.hashCode() : 0;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$sortByCount'"
                + ", id=" + filter
                + '}';
        }
    }

    private static class FacetStage implements Bson {

        private final List<Facet> facets;
        FacetStage(final List<Facet> facets) {
            this.facets = facets;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
            writer.writeStartDocument();
            writer.writeName("$facet");
            writer.writeStartDocument();
            for (Facet facet : facets) {
                writer.writeName(facet.getName());
                writer.writeStartArray();
                for (Bson bson : facet.getPipeline()) {
                    BuildersHelper.encodeValue(writer, bson, codecRegistry);
                }
                writer.writeEndArray();
            }
            writer.writeEndDocument();
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            FacetStage that = (FacetStage) o;

            return facets != null ? facets.equals(that.facets) : that.facets == null;
        }

        @Override
        public int hashCode() {
            return facets != null ? facets.hashCode() : 0;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$facet', "
                + "facets=" + facets + '}';
        }

    }

    private static class AddFieldsStage implements Bson {
        private final List<Field<?>> fields;

        AddFieldsStage(final List<Field<?>> fields) {
            this.fields = fields;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
            writer.writeStartDocument();
            writer.writeName("$addFields");
            writer.writeStartDocument();
            for (Field<?> field : fields) {
                writer.writeName(field.getName());
                BuildersHelper.encodeValue(writer, field.getValue(), codecRegistry);
            }
            writer.writeEndDocument();
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            AddFieldsStage that = (AddFieldsStage) o;

            return fields != null ? fields.equals(that.fields) : that.fields == null;
        }

        @Override
        public int hashCode() {
            return fields != null ? fields.hashCode() : 0;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$addFields', "
                + "fields=" + fields
                + '}';
        }
    }

    private static class ReplaceStage<TExpression> implements Bson {
        private final TExpression value;
        private final boolean replaceWith;

        ReplaceStage(final TExpression value) {
            this(value, false);
        }

        ReplaceStage(final TExpression value, final boolean replaceWith) {
            this.value = value;
            this.replaceWith = replaceWith;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> tDocumentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
            writer.writeStartDocument();

            if (replaceWith) {
                writer.writeName("$replaceWith");
                BuildersHelper.encodeValue(writer, value, codecRegistry);
            } else {
                writer.writeName("$replaceRoot");
                writer.writeStartDocument();
                writer.writeName("newRoot");
                BuildersHelper.encodeValue(writer, value, codecRegistry);
                writer.writeEndDocument();
            }
            writer.writeEndDocument();

            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            ReplaceStage<?> that = (ReplaceStage<?>) o;

            return value != null ? value.equals(that.value) : that.value == null;
        }

        @Override
        public int hashCode() {
            return value != null ? value.hashCode() : 0;
        }

        @Override
        public String toString() {
            return "Stage{"
                + "name='$replaceRoot', "
                + "value=" + value
                + '}';
        }
    }

    private static class MergeStage implements Bson {
        private final BsonValue intoValue;
        private final MergeOptions options;

        MergeStage(final BsonValue intoValue, final MergeOptions options) {
            this.intoValue = intoValue;
            this.options = options;
        }

        @Override
        public <TDocument> BsonDocument toBsonDocument(final Class<TDocument> documentClass, final CodecRegistry codecRegistry) {
            BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
            writer.writeStartDocument();
            writer.writeStartDocument("$merge");
            writer.writeName("into");
            if (intoValue.isString()) {
                writer.writeString(intoValue.asString().getValue());
            } else {
                writer.writeStartDocument();
                writer.writeString("db", intoValue.asDocument().getString("db").getValue());
                writer.writeString("coll", intoValue.asDocument().getString("coll").getValue());
                writer.writeEndDocument();
            }
            if (options.getUniqueIdentifier() != null) {
                if (options.getUniqueIdentifier().size() == 1) {
                    writer.writeString("on", options.getUniqueIdentifier().get(0));
                } else {
                    writer.writeStartArray("on");
                    for (String cur : options.getUniqueIdentifier()) {
                        writer.writeString(cur);
                    }
                    writer.writeEndArray();
                }
            }
            if (options.getVariables() != null) {
                writer.writeStartDocument("let");

                for (Variable<?> variable : options.getVariables()) {
                    writer.writeName(variable.getName());
                    BuildersHelper.encodeValue(writer, variable.getValue(), codecRegistry);
                }

                writer.writeEndDocument();
            }

            if (options.getWhenMatched() != null) {
                writer.writeName("whenMatched");
                switch (options.getWhenMatched()) {
                    case REPLACE:
                        writer.writeString("replace");
                        break;
                    case KEEP_EXISTING:
                        writer.writeString("keepExisting");
                        break;
                    case MERGE:
                        writer.writeString("merge");
                        break;
                    case PIPELINE:
                        writer.writeStartArray();
                        for (Bson curStage : options.getWhenMatchedPipeline()) {
                            BuildersHelper.encodeValue(writer, curStage, codecRegistry);
                        }
                        writer.writeEndArray();
                        break;
                    case FAIL:
                        writer.writeString("fail");
                        break;
                    default:
                        throw new UnsupportedOperationException("Unexpected value: " + options.getWhenMatched());
                }
            }
            if (options.getWhenNotMatched() != null) {
                writer.writeName("whenNotMatched");
                switch (options.getWhenNotMatched()) {
                    case INSERT:
                        writer.writeString("insert");
                        break;
                    case DISCARD:
                        writer.writeString("discard");
                        break;
                    case FAIL:
                        writer.writeString("fail");
                        break;
                    default:
                        throw new UnsupportedOperationException("Unexpected value: " + options.getWhenNotMatched());
                }
            }
            writer.writeEndDocument();
            writer.writeEndDocument();
            return writer.getDocument();
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            MergeStage that = (MergeStage) o;

            if (!intoValue.equals(that.intoValue)) {
                return false;
            }
            if (!options.equals(that.options)) {
                return false;
            }

            return true;
        }

        @Override
        public int hashCode() {
            int result = intoValue.hashCode();
            result = 31 * result + options.hashCode();
            return result;
        }

        @Override
        public String toString() {
            return "Stage{"
                    + "name='$merge', "
                    + ", into=" + intoValue
                    + ", options=" + options
                    + '}';
        }
    }

    private Aggregates() {
    }
}