NO TICKET: move level_status from observation to field_activity & rename | make observation value non-nullable

[jacob-a-brown]

Why

This PR addresses the following problem / context:

• an observation must have a value to be a valid observation, otherwise something occurred to prevent the observation from being observed.

How

Implementation summary - the following was changed / added / removed:

• made the value field in observation non-nullable
• move level_status from the observation table to the field_activity table and rename activity_status. This allows multiple activities to occur during an event, such as groundwater level and maintenance, but the status of one won't affect the status of the other.

Notes

Any special considerations, workarounds, or follow-up work to note?

• Use bullet points here

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

Files with missing lines	Coverage Δ
db/field.py	100.00% <100.00%> (ø)
db/observation.py	100.00% <ø> (ø)
schemas/field.py	100.00% <100.00%> (ø)
schemas/observation.py	98.33% <ø> (ø)
tests/conftest.py	98.81% <ø> (ø)
tests/test_observation.py	95.34% <ø> (ø)

[ksmuczynski]

Thinking more about lab data and value being nullable or not, I think it SHOULD be nullable. It's very common for labs to analyze samples, but the chemical is not present at a high enough concentration to be quantified. In these situations, the value is null, but there are lab qualifiers and reporting limits to provide further context.

[ksmuczynski]

Thinking more about lab data and value being nullable or not, I think it SHOULD be nullable. It's very common for labs to analyze samples, but the chemical is not present at a high enough concentration to be quantified. In these situations, the value is null, but there are lab qualifiers and reporting limits to provide further context.

I agree NULL values can be a pain to work with sometimes, but no result is a result and the Observation table has additional fields to explain why.

[jacob-a-brown]

Closing PR for more consideration, debate, and feedback from AMP before proceeding.