Ability to provide custom version check and increment strategies

[juanfiallo]

Currently when the @Version annotation is used in a Document's field, that field gets used for optimistic locking, this is achieved by providing a Criteria along with the update, which checks that the version being updated matches the current version of the object, when the update succeeds then the version gets auto-incremented. There doesn't seem to be any simple way of overriding this behavior, other than providing a custom MongoTemplate, even then the code path to override becomes pretty significant, since this is pretty deep down into some private classes, it'd basically result in a lot of duplication just to change a couple of lines of code. The code that builds the version aware query lives in org.springframework.data.mongodb.core.EntityOperations$MappedEntity.getQueryForVersion and the version increment code lives in org.springframework.data.mongodb.core.EntityOperations$AdaptibleMappedEntity.incrementVersion. The ask is to be able to provide custom strategies that can be customized instead of the current hardcoded logic, for example something like this:

interface VersionQueryStrategy {
    Query getQueryForVersion(MongoPersistentEntity<?> entity, Object id, Object version);
}

interface VersionIncrementStrategy {
    <T> T incrementVersion(MongoPersistentEntity<?> entity, ConvertingPropertyAccessor<T> propertyAccessor, Number version)
}

Just to provide some context my use case revolves around using a timestamp that I receive externally as the version field, and my desired query would check that the current version is less than the new version, and the increment logic would be completely skipped since the value is managed externally.

[mp911de]

Versions are meant to reflect the state of data within the database, not comparing it against some external information. It would be easier to override save methods in such case and perform the check yourself instead us generating more API surface. Generally, you can hook into the mapping process by registering an entity callback where you override the version in the Document to be saved.

I'm inclined to close this ticket unless there's a good reason to implement such a customization.

[spring-projects-issues]

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

[juanfiallo]

@mp911de that seems like a very narrow definition of what a version field should do, as I understand it a version it's meant to be simply that, some sort of marker that indicates some sort of revision metadata, not sure whether that being a manual value or auto-increment is really relevant. In my use case I'd like to increment the version myself, the fact that I'd like to grab it from an external source is specific to me but it's not the only possibility here. The other part of the equation, as I stated, is the query that checks the version itself, the current behavior works by checking that the version matches, but that only works when the version is managed in the current way but it breaks down with more complex cases like mine. I'm only asking for extension points because they don't currently exist in usual ways of inheritance or composition, at least not without having to duplicate a big portion of the framework code as part of a custom repository base class.