MongoDB $aggregate $push Java Spring数据中的多个字段
MongoDB $aggregate $push Java Spring数据中的多个字段
提问于 2016-09-08 22:31:25
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Java Spring-Data-MongoDB中的这个查询，我当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给push方法添加更多的字段(version，author，dateAdded)。用Spring-Data-MongoDB可以吗？
回答 3
Stack Overflow用户
回答已采纳
发布于 2016-11-24 22:48:34
您可以将BasicDbObject直接传递到任何聚合管道阶段。
Aggregation agg = newAggregation(
group("title").
push(new BasicDBObject
("version", "$version").append
("author", "$author").append
("dateAdded", "$dateAdded")).as("versions"));Stack Overflow用户
发布于 2016-09-09 15:15:56
说明： MongoDB版本2.6 - 3.0 (兼容的Java驱动程序)
我已经扩展了org.springframework.data.mongodb.core.aggregation.AggregationOperation类来实现自定义的toDBObject方法：
public class GenericAggregationOperation implements AggregationOperation {
private String operator;
private DBObject query;
/**
* Default constructor.
*
* @param operator MongoDB operator ($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, $project, etc..)
* @param query MongoDB aggregation query step DBObject
*/
public GenericAggregationOperation(String operator, DBObject query) {
this.operator = operator;
this.query = query;
}
@Override
public DBObject toDBObject(AggregationOperationContext context) {
return new BasicDBObject(operator, query);
}
}在您的情况下，它将是：
List<AggregationOperation> list = new ArrayList<AggregationOperation>();
lista.add(new GenericAggregationOperation("$group", "{ \"_id\": \"$title\", \"versions\": { \"$push\": { \"version\":\"$version\", \"author\":\"$author\", \"dateAdded\":\"$dateAdded\"}} }"));
TypedAggregation<EpisodeIndexDto> agg = Aggregation.newAggregation(
YourClassTitleVersion.class, list);
mongoOperations.aggregate(agg, YourClassTitleVersion.class,
YourClassTitleVersion.class).getMappedResults();希望这对你有帮助。
Stack Overflow用户
发布于 2018-08-01 18:26:36
在新版本spring-data-mongodb:2.x.x中，AggregationOperation需要返回文档而不是DBObject，因此更新后的类将是：
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import org.bson.Document;
import org.springframework.data.mongodb.core.aggregation.AggregationOperation;
import org.springframework.data.mongodb.core.aggregation.AggregationOperationContext;
public class GenericAggregationOperation implements AggregationOperation {
private String operator;
private DBObject query;
public GenericAggregationOperation(String operator, DBObject query) {
this.operator = operator;
this.query = query;
}
public GenericAggregationOperation(String operator, String query) {
this(operator, BasicDBObject.parse(query));
}
@Override
public Document toDocument(AggregationOperationContext context) {
return new Document(operator, query);
}
}另外，为了便于使用，我将添加实用程序接口(java 8+，对于java 7或更低版本，您可以将其转换为类utils )：
import com.mongodb.DBObject;
import org.springframework.data.mongodb.core.aggregation.AggregationOperation;
public interface GenericAggregationUtils {
static AggregationOperation aggregate(String operation, String query) {
return new GenericAggregationOperation(operation, query);
}
static AggregationOperation aggregate(String operation, DBObject query) {
return new GenericAggregationOperation(operation, query);
}
}然后我们可以将接口静态导入到我们的类中：
import static com.example.mongodb.aggregation.GenericAggregationUtils.*;并在聚合管道中与其他spring数据AggregationOperation一起使用，如下所示：
Aggregation aggregation = newAggregation(YourDocCollection.class,
aggregate("$group", "{ \"_id\": \"$title\", \"versions\": { \"$push\": { \"version\":\"$version\", \"author\":\"$author\", \"dateAdded\":\"$dateAdded\"}} }"),
sort(Sort.Direction.ASC, "title"),
...
);页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/39393672
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