Bug: Cascading to CaseSample table not set up

[islean]

Describe the bug

When deleting cases, there is no cascading nor constraints set up towards CaseSample, meaning that we get malformed entries with case_id = None. My understanding is that these should be deleted. IMPORTANT NOTE: the related sample entries should be left in place, only the CaseSample entries should get deleted.

Similarly, when deleting a sample, we have constraint in the CaseSample table preventing the sample_id from being set to None. So that sample is blocked from being deleted, whereas it probably should be deleted and its CaseSample entries should be removed as well.

To Reproduce

Have a case linked to a sample.

Delete the case.

Check the CaseSample entry

Acceptance criteria

• Deleting a case removes the case and any CaseSample entries with matching case_id
• Deleting a sample removes the sample and any Sample entries with matching sample_id

Questions

Should mother/father be cleared?