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The Java operations layer for the MongoDB Java Driver. Third parties can wrap this layer to provide custom higher-level APIs

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/*
 * 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.annotations.Beta;
import com.mongodb.client.model.search.FieldSearchPath;
import com.mongodb.client.model.search.SearchCollector;
import com.mongodb.client.model.search.SearchCount;
import com.mongodb.client.model.search.SearchOperator;
import com.mongodb.client.model.search.SearchOptions;
import com.mongodb.client.model.search.VectorSearchOptions;
import org.bson.BsonArray;
import org.bson.BsonDocument;
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 java.util.Objects;

import static com.mongodb.assertions.Assertions.notNull;
import static java.util.Arrays.asList;

/**
 * A factory for projections.   A convenient way to use this class is to statically import all of its methods, which allows usage like:
 *
 * 
 *    collection.find().projection(fields(include("x", "y"), excludeId()))
 * 
* * @mongodb.driver.manual tutorial/project-fields-from-query-results/#limit-fields-to-return-from-a-query Projection * @since 3.0 */ public final class Projections { private Projections() { } /** * Creates a projection of a field whose value is computed from the given expression. Projection with an expression can be used in the * following contexts: *
    *
  • $project aggregation pipeline stage.
  • *
  • Starting from MongoDB 4.4, it's also accepted in various find-related methods within the * {@code MongoCollection}-based API where projection is supported, for example: *
      *
    • {@code find()}
    • *
    • {@code findOneAndReplace()}
    • *
    • {@code findOneAndUpdate()}
    • *
    • {@code findOneAndDelete()}
    • *
    *
  • *
* * @param fieldName the field name * @param expression the expression * @param the expression type * @return the projection * @see #computedSearchMeta(String) * @see Aggregates#project(Bson) */ public static Bson computed(final String fieldName, final TExpression expression) { return new SimpleExpression<>(fieldName, expression); } /** * Creates a projection of a field whose value is equal to the {@code $$SEARCH_META} variable, * for use with {@link Aggregates#search(SearchOperator, SearchOptions)} / {@link Aggregates#search(SearchCollector, SearchOptions)}. * Calling this method is equivalent to calling {@link #computed(String, Object)} with {@code "$$SEARCH_META"} as the second argument. * * @param fieldName the field name * @return the projection * @see SearchCount * @see SearchCollector * @since 4.7 */ public static Bson computedSearchMeta(final String fieldName) { return computed(fieldName, "$$SEARCH_META"); } /** * Creates a projection that includes all of the given fields. * * @param fieldNames the field names * @return the projection */ public static Bson include(final String... fieldNames) { return include(asList(fieldNames)); } /** * Creates a projection that includes all of the given fields. * * @param fieldNames the field names * @return the projection */ public static Bson include(final List fieldNames) { return combine(fieldNames, new BsonInt32(1)); } /** * Creates a projection that excludes all of the given fields. * * @param fieldNames the field names * @return the projection */ public static Bson exclude(final String... fieldNames) { return exclude(asList(fieldNames)); } /** * Creates a projection that excludes all of the given fields. * * @param fieldNames the field names * @return the projection */ public static Bson exclude(final List fieldNames) { return combine(fieldNames, new BsonInt32(0)); } /** * Creates a projection that excludes the _id field. This suppresses the automatic inclusion of _id that is the default, even when * other fields are explicitly included. * * @return the projection */ public static Bson excludeId() { return new BsonDocument("_id", new BsonInt32(0)); } /** * Creates a projection that includes for the given field only the first element of an array that matches the query filter. This is * referred to as the positional $ operator. * * @param fieldName the field name whose value is the array * @return the projection * @mongodb.driver.manual reference/operator/projection/positional/#projection Project the first matching element ($ operator) */ public static Bson elemMatch(final String fieldName) { return new BsonDocument(fieldName + ".$", new BsonInt32(1)); } /** * Creates a projection that includes for the given field only the first element of the array value of that field that matches the given * query filter. * * @param fieldName the field name * @param filter the filter to apply * @return the projection * @mongodb.driver.manual reference/operator/projection/elemMatch elemMatch */ public static Bson elemMatch(final String fieldName, final Bson filter) { return new ElemMatchFilterProjection(fieldName, filter); } /** * Creates a $meta projection to the given field name for the given meta field name. * * @param fieldName the field name * @param metaFieldName the meta field name * @return the projection * @mongodb.driver.manual reference/operator/aggregation/meta/ * @since 4.1 * @see #metaTextScore(String) * @see #metaSearchScore(String) * @see #metaVectorSearchScore(String) * @see #metaSearchHighlights(String) */ public static Bson meta(final String fieldName, final String metaFieldName) { return new BsonDocument(fieldName, new BsonDocument("$meta", new BsonString(metaFieldName))); } /** * Creates a projection to the given field name of the textScore, for use with text queries. * Calling this method is equivalent to calling {@link #meta(String, String)} with {@code "textScore"} as the second argument. * * @param fieldName the field name * @return the projection * @see Filters#text(String, TextSearchOptions) * @mongodb.driver.manual reference/operator/aggregation/meta/#text-score-metadata--meta---textscore- textScore */ public static Bson metaTextScore(final String fieldName) { return meta(fieldName, "textScore"); } /** * Creates a projection to the given field name of the searchScore, * for use with {@link Aggregates#search(SearchOperator, SearchOptions)} / {@link Aggregates#search(SearchCollector, SearchOptions)}. * Calling this method is equivalent to calling {@link #meta(String, String)} with {@code "searchScore"} as the second argument. * * @param fieldName the field name * @return the projection * @mongodb.atlas.manual atlas-search/scoring/ Scoring * @since 4.7 */ public static Bson metaSearchScore(final String fieldName) { return meta(fieldName, "searchScore"); } /** * Creates a projection to the given field name of the vectorSearchScore, * for use with {@link Aggregates#vectorSearch(FieldSearchPath, Iterable, String, long, long, VectorSearchOptions)}. * Calling this method is equivalent to calling {@link #meta(String, String)} with {@code "vectorSearchScore"} as the second argument. * * @param fieldName the field name * @return the projection * @mongodb.atlas.manual atlas-search/scoring/ Scoring * @mongodb.server.release 6.0.10 * @since 4.11 */ @Beta(Beta.Reason.SERVER) public static Bson metaVectorSearchScore(final String fieldName) { return meta(fieldName, "vectorSearchScore"); } /** * Creates a projection to the given field name of the searchHighlights, * for use with {@link Aggregates#search(SearchOperator, SearchOptions)} / {@link Aggregates#search(SearchCollector, SearchOptions)}. * Calling this method is equivalent to calling {@link #meta(String, String)} with {@code "searchHighlights"} as the second argument. * * @param fieldName the field name * @return the projection * @see com.mongodb.client.model.search.SearchHighlight * @mongodb.atlas.manual atlas-search/highlighting/ Highlighting * @since 4.7 */ public static Bson metaSearchHighlights(final String fieldName) { return meta(fieldName, "searchHighlights"); } /** * Creates a projection to the given field name of a slice of the array value of that field. * * @param fieldName the field name * @param limit the number of elements to project. * @return the projection * @mongodb.driver.manual reference/operator/projection/slice Slice */ public static Bson slice(final String fieldName, final int limit) { return new BsonDocument(fieldName, new BsonDocument("$slice", new BsonInt32(limit))); } /** * Creates a projection to the given field name of a slice of the array value of that field. * * @param fieldName the field name * @param skip the number of elements to skip before applying the limit * @param limit the number of elements to project * @return the projection * @mongodb.driver.manual reference/operator/projection/slice Slice */ public static Bson slice(final String fieldName, final int skip, final int limit) { return new BsonDocument(fieldName, new BsonDocument("$slice", new BsonArray(asList(new BsonInt32(skip), new BsonInt32(limit))))); } /** * Creates a projection that combines the list of projections into a single one. If there are duplicate keys, the last one takes * precedence. * * @param projections the list of projections to combine * @return the combined projection */ public static Bson fields(final Bson... projections) { return fields(asList(projections)); } /** * Creates a projection that combines the list of projections into a single one. If there are duplicate keys, the last one takes * precedence. * * @param projections the list of projections to combine * @return the combined projection */ public static Bson fields(final List projections) { notNull("projections", projections); return new FieldsProjection(projections); } private static class FieldsProjection implements Bson { private final List projections; FieldsProjection(final List projections) { this.projections = projections; } @Override public BsonDocument toBsonDocument(final Class documentClass, final CodecRegistry codecRegistry) { BsonDocument combinedDocument = new BsonDocument(); for (Bson sort : projections) { BsonDocument sortDocument = sort.toBsonDocument(documentClass, codecRegistry); for (String key : sortDocument.keySet()) { combinedDocument.remove(key); combinedDocument.append(key, sortDocument.get(key)); } } return combinedDocument; } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } FieldsProjection that = (FieldsProjection) o; return Objects.equals(projections, that.projections); } @Override public int hashCode() { return projections != null ? projections.hashCode() : 0; } @Override public String toString() { return "Projections{" + "projections=" + projections + '}'; } } private static class ElemMatchFilterProjection implements Bson { private final String fieldName; private final Bson filter; ElemMatchFilterProjection(final String fieldName, final Bson filter) { this.fieldName = fieldName; this.filter = filter; } @Override public BsonDocument toBsonDocument(final Class documentClass, final CodecRegistry codecRegistry) { return new BsonDocument(fieldName, new BsonDocument("$elemMatch", filter.toBsonDocument(documentClass, codecRegistry))); } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } ElemMatchFilterProjection that = (ElemMatchFilterProjection) o; if (!Objects.equals(fieldName, that.fieldName)) { return false; } return Objects.equals(filter, that.filter); } @Override public int hashCode() { int result = fieldName != null ? fieldName.hashCode() : 0; result = 31 * result + (filter != null ? filter.hashCode() : 0); return result; } @Override public String toString() { return "ElemMatch Projection{" + "fieldName='" + fieldName + '\'' + ", filter=" + filter + '}'; } } private static Bson combine(final List fieldNames, final BsonValue value) { BsonDocument document = new BsonDocument(); for (String fieldName : fieldNames) { document.remove(fieldName); document.append(fieldName, value); } return document; } }




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