Add config option to load relationship fields.

[busykoala]

Close #444

Due to the recursive loading problem loading relations is not yet possible. This change introduces the config option 'include_relations' to also load specifically chosen relations.

For the current use case nothing changes unless the user specifically sets fields to be included (and carefully considers the risks of circular includes). The option is very valuable if the table design contains many 1:n relations.

Additionally, if the new config option was used with fastapi the tests show that the relation additionally has to be set to sa_relationship_kwargs={"lazy": "selectin"}), while the relations will not be returned otherwise.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ea79c47) 98.49% compared to head (962c9c8) 97.84%.
Report is 121 commits behind head on main.

❗ Current head 962c9c8 differs from pull request most recent head cbc9a0d. Consider uploading reports for the commit cbc9a0d to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #445      +/-   ##
==========================================
- Coverage   98.49%   97.84%   -0.66%     
==========================================
  Files         185      188       +3     
  Lines        5856     6450     +594     
==========================================
+ Hits         5768     6311     +543     
- Misses         88      139      +51     

Files	Coverage Δ
sqlmodel/main.py	85.42% <100.00%> (ø)
tests/test_relation_resolution.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[kennedy]

bump

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[emp-l]

That'd be very helpful and will reduce duplicated code. Any plans to merge this PR any time soon? 🙏

[Galtozzy]

Bump, is very simple yet will be insanely useful

[busykoala]

I haven’t looked into the latest changes on main, and I’m not confident about the current state of the code, since I haven’t worked on it in a while. I’m not sure what kind of impact this change would have on the codebase now, as things might have shifted quite a bit. Happy to revisit or close this if it’s more helpful for the project.