org.springframework.data.mongodb.core.mapreduce.GroupBy.java Source code

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Here is the source code for org.springframework.data.mongodb.core.mapreduce.GroupBy.java

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/*
 * Copyright 2010-2019 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.data.mongodb.core.mapreduce;

import java.util.Optional;

import org.bson.Document;
import org.springframework.data.mongodb.core.query.Collation;
import org.springframework.lang.Nullable;

/**
 * Collects the parameters required to perform a group operation on a collection. The query condition and the input
 * collection are specified on the group method as method arguments to be consistent with other operations, e.g.
 * map-reduce.
 *
 * @author Mark Pollack
 * @author Christoph Strobl
 * @author Mark Paluch
 * @deprecated since 2.2. The {@code group} command has been removed in MongoDB Server 4.2.0.
 */
@Deprecated
public class GroupBy {

    private @Nullable Document initialDocument;
    private @Nullable String reduce;

    private Optional<Document> keys = Optional.empty();
    private Optional<String> keyFunction = Optional.empty();
    private Optional<String> initial = Optional.empty();
    private Optional<String> finalize = Optional.empty();
    private Optional<Collation> collation = Optional.empty();

    public GroupBy(String... keys) {

        Document document = new Document();
        for (String key : keys) {
            document.put(key, 1);
        }

        this.keys = Optional.of(document);
    }

    // NOTE GroupByCommand does not handle keyfunction.

    public GroupBy(@Nullable String key, boolean isKeyFunction) {

        Document document = new Document();
        if (isKeyFunction) {
            keyFunction = Optional.ofNullable(key);
        } else {
            document.put(key, 1);
            keys = Optional.of(document);
        }
    }

    /**
     * Create new {@link GroupBy} with the field to group.
     *
     * @param key
     * @return
     */
    public static GroupBy keyFunction(String key) {
        return new GroupBy(key, true);
    }

    /**
     * Create new {@link GroupBy} with the fields to group.
     *
     * @param keys
     * @return
     */
    public static GroupBy key(String... keys) {
        return new GroupBy(keys);
    }

    /**
     * Define the aggregation result document.
     *
     * @param initialDocument can be {@literal null}.
     * @return
     */
    public GroupBy initialDocument(@Nullable String initialDocument) {

        initial = Optional.ofNullable(initialDocument);
        return this;
    }

    /**
     * Define the aggregation result document.
     *
     * @param initialDocument can be {@literal null}.
     * @return
     */
    public GroupBy initialDocument(@Nullable Document initialDocument) {

        this.initialDocument = initialDocument;
        return this;
    }

    /**
     * Define the aggregation function that operates on the documents during the grouping operation
     *
     * @param reduceFunction
     * @return
     */
    public GroupBy reduceFunction(String reduceFunction) {

        reduce = reduceFunction;
        return this;
    }

    /**
     * Define the function that runs each item in the result set before db.collection.group() returns the final value.
     *
     * @param finalizeFunction
     * @return
     */
    public GroupBy finalizeFunction(@Nullable String finalizeFunction) {

        finalize = Optional.ofNullable(finalizeFunction);
        return this;
    }

    /**
     * Define the Collation specifying language-specific rules for string comparison.
     *
     * @param collation can be {@literal null}.
     * @return
     * @since 2.0
     */
    public GroupBy collation(@Nullable Collation collation) {

        this.collation = Optional.ofNullable(collation);
        return this;
    }

    /**
     * Get the {@link Document} representation of the {@link GroupBy}.
     *
     * @return
     */
    public Document getGroupByObject() {

        Document document = new Document();

        keys.ifPresent(val -> document.append("key", val));
        keyFunction.ifPresent(val -> document.append("$keyf", val));

        document.put("$reduce", reduce);
        document.put("initial", initialDocument);

        initial.ifPresent(val -> document.append("initial", val));
        finalize.ifPresent(val -> document.append("finalize", val));
        collation.ifPresent(val -> document.append("collation", val.toDocument()));

        return document;
    }

}