CommunityLibrarySubmission model

[Jakoma02]

Summary

I implemented CommunityLibrarySubmission model and tests for it according to specs in #5145.

I have tested the changes by running pytest tests and making sure that the new tests pass and the existing tests do not break, and I have made sure that the devserver still starts.

References

Resolves#5145.

Reviewer guidance

I have decided to override the clean method to validate that the author of the submission should be an editor of the corresponding channel. This cannot be achieved using a database constraint because traversing related fields is not supported inside them. This way, the constraint will be checked when using forms and when explicitly calling full_clean() (not on every save). Please check that this solution matches your expectations.

[AlexVelezLl]

This is looking great @Jakoma02! Thanks! Just a couple of nitpick comments, but this is looking great! :)

[AlexVelezLl]

We usually do these validations at api level, but can imagine the benefits of doing this at model level. This doesn't seem to be a common pattern in our codebase thought, would like to hear @rtibbles thoughts, as we may also need to do the check of the version being version > 0 and version <= channel.version

[rtibbles]

When we have done these kinds of validations on the model itself, we have usually done it in the save method rather than the clean method - for precisely the reasons noted in the docstring - clean is not called on every save, but only when using a Django model form (which we rarely use).

If we want to ensure that this is being used every time we save a model, we should put it in the save method instead, otherwise, I think it would sit better in the API endpoint.

[Jakoma02]

Okay, if you agree, I will move the logic to the save method.

[AlexVelezLl]

Yes, lets move this logic to the save method, along with the version check. Thanks!

[Jakoma02]

Added in 7f17512 and f0a05eb.

[AlexVelezLl]

Thank youu! <3 Just one little thing before we merge (I promise this is the last one 😅):

Could you remove the translate function from the error messages? We use to return these validation error messages without translating them e.g. here.

[Jakoma02]

I removed translation in cb61cb1.

[AlexVelezLl]

Thanks!

[AlexVelezLl]

Code changes looks good and tests are passing, the first lines of code of this project are ready to go! Thanks a lot @Jakoma02! Merging!