org.springframework.data.mongodb.repository

Annotation Type Aggregation

@Retention(value=RUNTIME)
 @Target(value={METHOD,ANNOTATION_TYPE})
 @Documented
public @interface Aggregation

The Aggregation annotation can be used to annotate a Repository query method so that it runs the pipeline() on invocation.

Pipeline stages are mapped against the Repository domain type to consider field mappings and may contain simple placeholders ?0 as well as SpelExpressions.

Query method Sort and Pageable arguments are applied at the end of the pipeline or can be defined manually as part of it.

Since:

2.2

Author:

Christoph Strobl

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	collation Defines the collation to apply when executing the aggregation.
String[]	pipeline Defines the aggregation pipeline to apply.
String[]	value Alias for pipeline().

Element Detail

value

@AliasFor(value="pipeline")
public abstract String[] value

Alias for pipeline(). Defines the aggregation pipeline to apply.

Returns:

an empty array by default.

See Also:

pipeline()

Default:

{}

pipeline

@AliasFor(value="value")
public abstract String[] pipeline

Defines the aggregation pipeline to apply.

 // aggregation resulting in collection with single value
 @Aggregation("{ '$project': { '_id' : '$lastname' } }")
 List findAllLastnames();

 // aggregation with parameter replacement
 @Aggregation("{ '$group': { '_id' : '$lastname', names : { $addToSet : '$?0' } } }")
 List groupByLastnameAnd(String property);

 // aggregation with sort in pipeline
 @Aggregation(pipeline = {"{ '$group': { '_id' : '$lastname', names : { $addToSet : '$?0' } } }", "{ '$sort' : { 'lastname' : -1 } }"})
 List groupByLastnameAnd(String property);

 // Sort parameter is used for sorting results
 @Aggregation("{ '$group': { '_id' : '$lastname', names : { $addToSet : '$?0' } } }")
 List groupByLastnameAnd(String property, Sort sort);

 // Pageable parameter used for sort, skip and limit
 @Aggregation("{ '$group': { '_id' : '$lastname', names : { $addToSet : '$?0' } } }")
 List groupByLastnameAnd(String property, Pageable page);

 // Single value result aggregation.
 @Aggregation("{ '$group' : { '_id' : null, 'total' : { $sum: '$age' } } }")
 Long sumAge();

 // Single value wrapped in container object
 @Aggregation("{ '$group' : { '_id' : null, 'total' : { $sum: '$age' } } })
 SumAge sumAgeAndReturnAggregationResultWrapperWithConcreteType();

 // Raw aggregation result
 @Aggregation("{ '$group' : { '_id' : null, 'total' : { $sum: '$age' } } })
 AggregationResults<org.bson.Document>> sumAgeAndReturnAggregationResultWrapper();
 

Returns:

an empty array by default.

Default:

{}

collation

public abstract String collation

Defines the collation to apply when executing the aggregation.

 // Fixed value
 @Aggregation(pipeline = "...", collation = "en_US")
 List findAllByFixedCollation();

 // Fixed value as Document
 @Aggregation(pipeline = "...", collation = "{ 'locale' :  'en_US' }")
 List findAllByFixedJsonCollation();

 // Dynamic value as String
 @Aggregation(pipeline = "...", collation = "?0")
 List findAllByDynamicCollation(String collation);

 // Dynamic value as Document
 @Aggregation(pipeline = "...", collation = "{ 'locale' :  ?0 }")
 List findAllByDynamicJsonCollation(String collation);

 // SpEL expression
 @Aggregation(pipeline = "...", collation = "?#{[0]}")
 List findAllByDynamicSpElCollation(String collation);
 

Returns:

an empty String by default.

Default:

""