Spring Data MongoDB - Spring Web Services - Parent - SpringSource

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please define productname in your docbook file!public class XObject {private float x;private float count;public float getX() {return x;}public void setX(float x) {this.x = x;}public float getCount() {return count;}public void setCount(float count) {this.count = count;}}@Overridepublic String toString() {return "XObject [x=" + x + " count = " + count + "]";}You can also obtain tha raw result as a DbObject by calling the method getRawResults on theGroupByResults class.There is an additional method overload of the group method on MongoOperations which lets youspecify a Criteria object for selecting a subset of the rows. An example which uses a Criteriaobject, with some syntax sugar using static imports, as well as referencing a key-function and reducefunction javascript files via a Spring Resource string is shown below.import static org.springframework.data.mongodb.core.mapreduce.GroupBy.keyFunction;import static org.springframework.data.mongodb.core.query.Criteria.where;GroupByResults results = mongoTemplate.group(where("x").gt(0),"group_test_collection",keyFunction("classpath:keyFunction.js").initialDocument("{ count:0 }").reduceFunction("classpath:groupReduce.js"), XObject.class);5.9 Aggregation Framework SupportSpring Data MongoDB provides support for the Aggregation Framework introduced to MongoDB inversion 2.2.The MongoDB Documentation describes the Aggregation Framework as follows:“The MongoDBaggregation framework provides a means to calculate aggregated values without having to use mapreduce.While map-reduce is powerful, it is often more difficult than necessary for many simpleaggregation tasks, such as totaling or averaging field values.”For further information see the full reference documentation of the aggregation framework and otherdata aggregation tools for MongoDB.1.4.0.BUILD-SNAPSHOTSpring Data MongoDB -Reference Documentation 53
please define productname in your docbook file!Basic ConceptsThe Aggregation Framework support in Spring Data MongoDB is based on the following key abstractionsAggregation, AggregationOperation and AggregationResults.• AggregationAn Aggregation represents a MongoDB aggregate operation and holds the description ofthe aggregation pipline instructions. Aggregations are created by inoking the appropriatenewAggregation(…) static factory Method of the Aggregation class which takes the list ofAggregateOperation as a parameter next to the optional input class.The actual aggregate operation is executed by the aggregate method of the MongoTemplate whichalso takes the desired output class as parameter.• AggregationOperationAn AggregationOperation represents a MongoDB aggregation pipeline operation and describesthe processing that should be performed in this aggregation step. Although one could manually createan AggregationOperation the recommended way to construct an AggregateOperation is touse the static factory methods provided by the Aggregate class.• AggregationResultsAggregationResults is the container for the result of an aggregate operation. It provides accessto the raw aggreation result in the form of an DBObject, to the mapped objects and information whichperformed the aggregation.The canonical example for using the Spring Data MongoDB support for the MongoDB AggregationFramework looks as follows:import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;Aggregation agg = newAggregation(pipelineOP1(),pipelineOP2(),pipelineOPn());AggregationResults results =mongoTemplate.aggregate(agg, "INPUT_COLLECTION_NAME", OutputType.class);List mappedResult = results.getMappedResults();Note that if you provide an input class as the first parameter to the newAggregation method theMongoTemplate will derive the name of the input collection from this class. Otherwise if you don't notspecify an input class you must provide the name of the input collection explicitly. If an input-class andan explicity input-collection is provided the latter takes precedence.Supported Aggregation OperationsThe MongoDB Aggregation Framework provides the following types of Aggregation Operations:• Pipeline Aggregation Operators• Group Aggregation Operators1.4.0.BUILD-SNAPSHOTSpring Data MongoDB -Reference Documentation 54
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