MongoDB $ aggregate $ push Java Spring Data中的多个字段

我有一个mongo聚合组查询：

db.wizard.aggregate( { $group: { _id: "$title", versions: { $push: {version:"$version", author:"$author", dateAdded:"$dateAdded"}} } }) 

我需要在Java Spring-Data-MongoDB中使用此查询，我目前的解决方案如下所示：

  Aggregation agg = Aggregation.newAggregation( Aggregation.group("title"). push("version").as("versions") ); 

问题是我不知道如何为push方法添加更多字段（版本，作者，dateAdded）。 是否可以使用Spring-Data-MongoDB？

Answer 1

注意： MongoDBversión2.6 – 3.0（兼容的Java驱动程序）

我已经扩展了org.springframework.data.mongodb.core.aggregation.AggregationOperation类来实现自定义toDBObject方法：

 public class GenericAggregationOperation implements AggregationOperation { private String operator; private DBObject query; /** * Default constructor. * * @param operator MongoDB operator ($group, $sort, $project, etc..) * @param query MongoDB aggregation query step string */ public GenericAggregationOperation(String operator, String query) { this(operator, (DBObject) JSON.parse(query)); } /** * Default constructor. * * @param operator MongoDB operator ($group, $sort, $project, etc..) * @param query MongoDB aggregation query step DBObject */ public GenericAggregationOperation(String operator, DBObject query) { this.operator = operator; this.query = query; } @Override public DBObject toDBObject(AggregationOperationContext context) { return new BasicDBObject(operator, query); } } 

在你的情况下，它将是：

 List list = new ArrayList(); lista.add(new GenericAggregationOperation("$group", "{ \"_id\": \"$title\", \"versions\": { \"$push\": { \"version\":\"$version\", \"author\":\"$author\", \"dateAdded\":\"$dateAdded\"}} }")); TypedAggregation agg = Aggregation.newAggregation( YourClassTitleVersion.class, list); mongoOperations.aggregate(agg, YourClassTitleVersion.class, YourClassTitleVersion.class).getMappedResults(); 

希望这对你有所帮助。

Answer 2

您可以直接将BasicDbObject传递给任何聚合管道阶段。

 Aggregation agg = newAggregation( group("title"). push(new BasicDBObject ("version", "$version").append ("author", "$author").append ("dateAdded", "$dateAdded")).as("versions")); 

Answer 3

在新版本spring-data-mongodb：2.xx中，AggregationOperation需要返回Document而不是DBObject，因此更新后的类将是：

 import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import org.bson.Document; import org.springframework.data.mongodb.core.aggregation.AggregationOperation; import org.springframework.data.mongodb.core.aggregation.AggregationOperationContext; public class GenericAggregationOperation implements AggregationOperation { private String operator; private DBObject query; public GenericAggregationOperation(String operator, DBObject query) { this.operator = operator; this.query = query; } public GenericAggregationOperation(String operator, String query) { this(operator, BasicDBObject.parse(query)); } @Override public Document toDocument(AggregationOperationContext context) { return new Document(operator, query); } } 

另外，为了方便使用，我将添加实用程序界面（java 8+，对于java 7或更低版​​本，您可以将其转换为类utils）：

 import com.mongodb.DBObject; import org.springframework.data.mongodb.core.aggregation.AggregationOperation; public interface GenericAggregationUtils { static AggregationOperation aggregate(String operation, String query) { return new GenericAggregationOperation(operation, query); } static AggregationOperation aggregate(String operation, DBObject query) { return new GenericAggregationOperation(operation, query); } } 

然后我们可以将接口静态导入到我们的类中：

 import static com.example.mongodb.aggregation.GenericAggregationUtils.*; 

并将其与其他弹簧数据AggregationOperation一起用于聚合管道中，如下所示：

 Aggregation aggregation = newAggregation(YourDocCollection.class, aggregate("$group", "{ \"_id\": \"$title\", \"versions\": { \"$push\": { \"version\":\"$version\", \"author\":\"$author\", \"dateAdded\":\"$dateAdded\"}} }"), sort(Sort.Direction.ASC, "title"), ... );