Spring/spring-data-mongodb
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Polishing.

Browse Source 
Let appendLimitAndOffsetIfPresent accept unary operators for adjusting limit/offset values instead of appendModifiedLimitAndOffsetIfPresent. Apply simple type extraction for Slice. Add support for aggregation result streaming.

Extend tests, add author tags, update docs.

See #3543.
Original pull request: #3645.
This commit is contained in:
Mark Paluch
2021-05-11 11:47:36 +02:00
parent 9a48e32565
commit 90d03d92d8
6 changed files with 186 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
src/main/asciidoc/reference/mongo-repositories-aggregation.adoc
View File

@@ -21,19 +21,22 @@ public interface PersonRepository extends CrudReppsitory<Person, String> {
List<PersonAggregate> groupByLastnameAnd(String property); <3>
@Aggregation("{ $group: { _id : $lastname, names : { $addToSet : ?0 } } }")
List<PersonAggregate> groupByLastnameAnd(String property, Pageable page); <4>
Slice<PersonAggregate> groupByLastnameAnd(String property, Pageable page); <4>
@Aggregation("{ $group: { _id : $lastname, names : { $addToSet : $firstname } } }")
Stream<PersonAggregate> groupByLastnameAndFirstnamesAsStream(); <5>
@Aggregation("{ $group : { _id : null, total : { $sum : $age } } }")
SumValue sumAgeUsingValueWrapper(); <5>
SumValue sumAgeUsingValueWrapper(); <6>
@Aggregation("{ $group : { _id : null, total : { $sum : $age } } }")
Long sumAge(); <6>
Long sumAge(); <7>
@Aggregation("{ $group : { _id : null, total : { $sum : $age } } }")
AggregationResults<SumValue> sumAgeRaw(); <7>
AggregationResults<SumValue> sumAgeRaw(); <8>
@Aggregation("{ '$project': { '_id' : '$lastname' } }")
List<String> findAllLastnames(); <8>
List<String> findAllLastnames(); <9>
}
----
[source,java]
@@ -52,7 +55,7 @@ public class PersonAggregate {
public class SumValue {
private final Long total; <5> <7>
private final Long total; <6> <8>
public SumValue(Long total) {
// ...
@@ -65,12 +68,13 @@ public class SumValue {
<2> If `Sort` argument is present, `$sort` is appended after the declared pipeline stages so that it only affects the order of the final results after having passed all other aggregation stages.
Therefore, the `Sort` properties are mapped against the methods return type `PersonAggregate` which turns `Sort.by("lastname")` into `{ $sort : { '_id', 1 } }` because `PersonAggregate.lastname` is annotated with `@Id`.
<3> Replaces `?0` with the given value for `property` for a dynamic aggregation pipeline.
<4> `$skip`, `$limit` and `$sort` can be passed on via a `Pageable` argument. Same as in <2>, the operators are appended to the pipeline definition.
<5> Map the result of an aggregation returning a single `Document` to an instance of a desired `SumValue` target type.
<6> Aggregations resulting in single document holding just an accumulation result like eg. `$sum` can be extracted directly from the result `Document`.
<4> `$skip`, `$limit` and `$sort` can be passed on via a `Pageable` argument. Same as in <2>, the operators are appended to the pipeline definition. Methods accepting `Pageable` can return `Slice` for easier pagination.
<5> Aggregation methods can return `Stream` to consume results directly from an underlying cursor. Make sure to close the stream after consuming it to release the server-side cursor by either calling `close()` or through `try-with-resources`.
<6> Map the result of an aggregation returning a single `Document` to an instance of a desired `SumValue` target type.
<7> Aggregations resulting in single document holding just an accumulation result like eg. `$sum` can be extracted directly from the result `Document`.
To gain more control, you might consider `AggregationResult` as method return type as shown in <7>.
<7> Obtain the raw `AggregationResults` mapped to the generic target wrapper type `SumValue` or `org.bson.Document`.
<8> Like in <6>, a single value can be directly obtained from multiple result ``Document``s.
<8> Obtain the raw `AggregationResults` mapped to the generic target wrapper type `SumValue` or `org.bson.Document`.
<9> Like in <6>, a single value can be directly obtained from multiple result ``Document``s.
====
In some scenarios, aggregations might require additional options, such as a maximum run time, additional log comments, or the permission to temporarily write data to disk.
@@ -115,5 +119,5 @@ Simple-type single-result inspects the returned `Document` and checks for the fo
. Throw an exception if none of the above is applicable.
====
WARNING: The `Page` return type is not supported for repository methods using `@Aggregation`. However you can use a
`Pageable` argument to add `$skip`, `$limit` and `$sort` to the pipeline.
WARNING: The `Page` return type is not supported for repository methods using `@Aggregation`. However, you can use a
`Pageable` argument to add `$skip`, `$limit` and `$sort` to the pipeline and let the method return `Slice`.