DuplicateKeyException on save lazy loaded references

[MuravlevAS]

Mongo repository throws DuplicateKeyException when I use save() method with object that was lazily loaded
from @DocumentReference

spring-data-mongodb version: 4.5.1

Failing test in demo project that shows the bug:
https://github.com/MuravlevAS/spring-mongodb-reference-demo/blob/master/src/test/java/com/example/demo/Demo1ApplicationTests.java#L25-L45

[christophstrobl]

@MuravlevAS seems the demo is in a private repo.

[MuravlevAS]

@MuravlevAS seems the demo is in a private repo.

@christophstrobl I am so sorry. I have changed it to public. Do you have access now?

[christophstrobl]

Thank you for the reproducer - seems as if the EntityInformation does not extract the proxy target for the isNew check, which in turn will call insert leading to the error.

[MuravlevAS]

Will this fix be added in 4.x version?

[mp911de]

For the time being, the fix (to address the issue entirely) is only shipped with the 5.0 version. I suggest that you unwrap the lazy-loading proxy (LazyLoadingProxy.getTarget()) before saving to avoid the issue. Saving proxies never worked well really and the change has to happen at a place that affects all objects imposing quite some risk of unintentionally breaking application behavior.