DATAMONGO-1552 - Add $bucket aggregation stage.

Original Pull Request: #426

Author: mp911de

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/Aggregation.java

@@ -202,7 +202,7 @@ public static ProjectionOperation project(String... fields) {
 	}
 
 	/**
-	 * Creates a new {@link ProjectionOperation} includeing the given {@link Fields}.
+	 * Creates a new {@link ProjectionOperation} including the given {@link Fields}.
 	 *
 	 * @param fields must not be {@literal null}.
 	 * @return
@@ -418,6 +418,26 @@ public static OutOperation out(String outCollectionName) {
 		return new OutOperation(outCollectionName);
 	}
 
+	/**
+	 * Creates a new {@link BucketOperation} using given {@literal groupByField}.
+	 *
+	 * @param groupByField must not be {@literal null} or empty.
+	 * @return
+	 */
+	public static BucketOperation bucket(String groupByField) {
+		return new BucketOperation(field(groupByField));
+	}
+
+	/**
+	 * Creates a new {@link BucketOperation} using given {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 * @return
+	 */
+	public static BucketOperation bucket(AggregationExpression groupByExpression) {
+		return new BucketOperation(groupByExpression);
+	}
+
 	/**
 	 * Creates a new {@link LookupOperation}.
 	 *

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/BucketOperation.java

@@ -0,0 +1,226 @@
+/*
+ * Copyright 2016 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
+ *
+ *      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 org.springframework.data.mongodb.core.aggregation;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.data.mongodb.core.aggregation.BucketOperation.BucketOperationOutputBuilder;
+import org.springframework.util.Assert;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DBObject;
+
+/**
+ * Encapsulates the aggregation framework {@code $bucket}-operation.
+ * <p>
+ * Bucket stage is typically used with {@link Aggregation} and {@code $facet}. Categorizes incoming documents into
+ * groups, called buckets, based on a specified expression and bucket boundaries.
+ * <p>
+ * We recommend to use the static factory method {@link Aggregation#bucket(String)} instead of creating instances of
+ * this class directly.
+ *
+ * @see http://docs.mongodb.org/manual/reference/aggregation/bucket/
+ * @see BucketOperationSupport
+ * @author Mark Paluch
+ * @since 1.10
+ */
+public class BucketOperation extends BucketOperationSupport<BucketOperation, BucketOperationOutputBuilder>
+		implements FieldsExposingAggregationOperation {
+
+	private final List<Object> boundaries;
+	private final Object defaultBucket;
+
+	/**
+	 * Creates a new {@link BucketOperation} given a {@link Field group-by field}.
+	 *
+	 * @param groupByField must not be {@literal null}.
+	 */
+	public BucketOperation(Field groupByField) {
+
+		super(groupByField);
+
+		this.boundaries = Collections.emptyList();
+		this.defaultBucket = null;
+	}
+
+	/**
+	 * Creates a new {@link BucketOperation} given a {@link AggregationExpression group-by expression}.
+	 *
+	 * @param groupByExpression must not be {@literal null}.
+	 */
+	public BucketOperation(AggregationExpression groupByExpression) {
+
+		super(groupByExpression);
+
+		this.boundaries = Collections.emptyList();
+		this.defaultBucket = null;
+	}
+
+	private BucketOperation(BucketOperation bucketOperation, Outputs outputs) {
+
+		super(bucketOperation, outputs);
+
+		this.boundaries = bucketOperation.boundaries;
+		this.defaultBucket = bucketOperation.defaultBucket;
+	}
+
+	private BucketOperation(BucketOperation bucketOperation, List<Object> boundaries, Object defaultBucket) {
+
+		super(bucketOperation);
+
+		this.boundaries = new ArrayList<Object>(boundaries);
+		this.defaultBucket = defaultBucket;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
+	@Override
+	public DBObject toDBObject(AggregationOperationContext context) {
+
+		DBObject options = new BasicDBObject();
+
+		options.put("boundaries", context.getMappedObject(new BasicDBObject("$set", boundaries)).get("$set"));
+
+		if (defaultBucket != null) {
+			options.put("default", context.getMappedObject(new BasicDBObject("$set", defaultBucket)).get("$set"));
+		}
+
+		options.putAll(super.toDBObject(context));
+
+		return new BasicDBObject("$bucket", options);
+	}
+
+	/**
+	 * Configures a default bucket {@literal literal} and return a new {@link BucketOperation}.
+	 * 
+	 * @param literal must not be {@literal null}.
+	 * @return
+	 */
+	public BucketOperation withDefaultBucket(Object literal) {
+
+		Assert.notNull(literal, "Default bucket literal must not be null!");
+		return new BucketOperation(this, boundaries, literal);
+	}
+
+	/**
+	 * Configures {@literal boundaries} and return a new {@link BucketOperation}. Existing {@literal boundaries} are
+	 * preserved and the new {@literal boundaries} are appended.
+	 * 
+	 * @param boundaries must not be {@literal null}.
+	 * @return
+	 */
+	public BucketOperation withBoundaries(Object... boundaries) {
+
+		Assert.notNull(boundaries, "Boundaries must not be null!");
+
+		List<Object> newBoundaries = new ArrayList<Object>(this.boundaries.size() + boundaries.length);
+		newBoundaries.addAll(this.boundaries);
+		newBoundaries.addAll(Arrays.asList(boundaries));
+
+		return new BucketOperation(this, newBoundaries, defaultBucket);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#newBucketOperation(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.Outputs)
+	 */
+	@Override
+	protected BucketOperation newBucketOperation(Outputs outputs) {
+		return new BucketOperation(this, outputs);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutputExpression(java.lang.String, java.lang.Object[])
+	 */
+	@Override
+	public ExpressionBucketOperationBuilder andOutputExpression(String expression, Object... params) {
+		return new ExpressionBucketOperationBuilder(expression, this, params);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(org.springframework.data.mongodb.core.aggregation.AggregationExpression)
+	 */
+	@Override
+	public BucketOperationOutputBuilder andOutput(AggregationExpression expression) {
+		return new BucketOperationOutputBuilder(expression, this);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport#andOutput(java.lang.String)
+	 */
+	@Override
+	public BucketOperationOutputBuilder andOutput(String fieldName) {
+		return new BucketOperationOutputBuilder(Fields.field(fieldName), this);
+	}
+
+	/**
+	 * {@link OutputBuilder} implementation for {@link BucketOperation}.
+	 */
+	public static class BucketOperationOutputBuilder
+			extends BucketOperationSupport.OutputBuilder<BucketOperationOutputBuilder, BucketOperation> {
+
+		/**
+		 * Creates a new {@link BucketOperationOutputBuilder} fot the given value and {@link BucketOperation}.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 */
+		protected BucketOperationOutputBuilder(Object value, BucketOperation operation) {
+			super(value, operation);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+
+	/**
+	 * {@link ExpressionBucketOperationBuilderSupport} implementation for {@link BucketOperation} using SpEL expression
+	 * based {@link Output}.
+	 * 
+	 * @author Mark Paluch
+	 */
+	public static class ExpressionBucketOperationBuilder
+			extends ExpressionBucketOperationBuilderSupport<BucketOperationOutputBuilder, BucketOperation> {
+
+		/**
+		 * Creates a new {@link ExpressionBucketOperationBuilderSupport} for the given value, {@link BucketOperation}
+		 * and parameters.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @param operation must not be {@literal null}.
+		 * @param parameters
+		 */
+		protected ExpressionBucketOperationBuilder(String expression, BucketOperation operation, Object[] parameters) {
+			super(expression, operation, parameters);
+		}
+
+		/* (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OutputBuilder#apply(org.springframework.data.mongodb.core.aggregation.BucketOperationSupport.OperationOutput)
+		 */
+		@Override
+		protected BucketOperationOutputBuilder apply(OperationOutput operationOutput) {
+			return new BucketOperationOutputBuilder(operationOutput, this.operation);
+		}
+	}
+}