Fix deleting beliefs in CLI

[Ragnar-the-mighty]

fixes #1092 1092

There are more places that has same issues but I do not have test cases so I only fixed this one.

Description

The cli command flexmeasures delete prognoses
returns
TypeError: %d format: a real number is required, not CursorResult

The reason is that after move to SQLAlchemy 2 the code
num_forecasts_deleted = db.session.execute(query)
Does not work as it use to do.

The fix is to use .rowcount as recommended by SQLAlchemy 2 documentation

Look & Feel

No change in UI
No change in CLI parameter or API endpoints

How to test

Call the cli command
flexmeasures delete prognoses
It should no longer throw the
TypeError: %d format: a real number is required, not CursorResult

Further Improvements

There are more instances of
num_forecasts_deleted = db.session.execute(query)
But I am a newbee and I do not have test cases for the other instances.

Related Items

This should close issues #1092

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• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

[nhoening]

Thanks for helping to fix this!

Let's fix the other instances as well, and also the flexmeasures delete beliefs command I mentioned in #1092

We can do this, especially because with the help of this method of adding data we can create whatever we want, then attempt to delete it :)

[Ragnar-the-mighty]

OK, I try to fix the other instances and the also the flexmeasures delete beliefs command

[nhoening]

Thanks!

[Ragnar-the-mighty]

Hmm, I did not change flexmeasures/cli/data_delete.py and the flexmeasures delete beliefs command work for me.

I am not trusting my code changes and I do not want to cause work for anyone else.
I appreciate the help I got to unblock myself.
I will suspend work on PR until I have more confidence that I understand what I am doing.

[nhoening]

Yes, flexmeasures delete beliefs also works for me, not sure what the difference is. I also got flexmeasures delete unchanged-beliefs to work.

Then this PR should simply concentrate on flexmeasures delete measurements (which I tested to have the same bug you reported). Can you apply the fix there, we well? Then I believe we did a good step with this PR.

[Ragnar-the-mighty]

Nicolas, thank you for testing and merging the code, I hope that I will be able to do test better and fix any issues blocking merge

[nhoening]

I believe the remaining work would be to simply repeat what you did for one command in the other one.

[nhoening]

Hi @Ragnar-the-mighty are you able to fix the other command we talked about as well (flexmeasures delete measurements)? I guess that is all we should be doing here and then we can merge.