Spring/spring-data-r2dbc
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

#302 - Add documentation for entity-state detection.

Browse Source
This commit is contained in:
Mark Paluch
2020-02-14 13:50:05 +01:00
parent 79a1965364
commit a6d891093e
1 changed files with 29 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
src/main/asciidoc/reference/r2dbc-repositories.adoc
View File

@@ -149,6 +149,35 @@ The result of a modifying query can be:
The `@Modifying` annotation is only relevant in combination with the `@Query` annotation.
Derived custom methods do not require this annotation.
[[r2dbc.entity-persistence.state-detection-strategies]]
=== Entity State Detection Strategies
The following table describes the strategies that Spring Data R2DBC offers for detecting whether an entity is new:
.Options for detection whether an entity is new in Spring Data R2DBC
[options = "autowidth"]
|===============
|Id-Property inspection (the default) |By default, the `save()` method inspects the identifier property of the given entity.
If the identifier property is `null`, then the entity is assumed to be new. Otherwise, it is assumed exist in the datbase.
|Implementing `Persistable` |If an entity implements `Persistable`, Spring Data R2DBC delegates the new detection to the `isNew(…)` method of the entity.
See the link:$$https://docs.spring.io/spring-data/data-commons/docs/current/api/index.html?org/springframework/data/domain/Persistable.html$$[Javadoc] for details.
|Implementing `EntityInformation` |You can customize the `EntityInformation` abstraction used in `SimpleR2dbcRepository` by creating a subclass of `R2dbcRepositoryFactory` and overriding `getEntityInformation(…)`.
You then have to register the custom implementation of `R2dbcRepositoryFactory` as a Spring bean.
Note that this should rarely be necessary. See the link:{spring-data-r2dbc-javadoc}/org/springframework/data/r2dbc/repository/support/R2dbcRepositoryFactory.html[Javadoc] for details.
|===============
[[r2dbc.entity-persistence.id-generation]]
=== ID Generation
Spring Data R2DBC uses the ID to identify entities.
The ID of an entity must be annotated with Spring Data's https://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/annotation/Id.html[`@Id`] annotation.
When your database has an auto-increment column for the ID column, the generated value gets set in the entity after inserting it into the database.
One important constraint is that, after saving an entity, the entity must not be new anymore.
Note that whether an entity is new is part of the entity's state.
With auto-increment columns, this happens automatically, because the ID gets set by Spring Data with the value from the ID column.
:projection-collection: Flux
include::../{spring-data-commons-docs}/repository-projections.adoc[leveloffset=+2]