Add ability to export filtered QuerySet of FilterView to JSON format

[aayushkdev]

fix #1319

Added the ability to export the current filtered QuerySet of a FilterView into the JSON format.

[tdruez]

@aayushkdev The implementation looks fine but we need a few unit tests before merging.

[aayushkdev]

Hey, thanks for the review. I have exams going on right now, so I'll add the unit tests as soon as they're finished.

[aayushkdev]

Hey @tdruez, I have pushed the required unit tests. Could you please check if they are fit for merging

[tdruez]

1. The ExportJSONMixin is used for all the object models but only the CodebaseResourceListView returns a valid response.
   The code breaks if you try to export from any other list view, such as packages.
   The tests are incomplete as those only test for the resource type.

2. The returned JSON is not valid when multiple records are included. It seems that the comma is missing.

[aayushkdev]

Hey @tdruez I have pushed the required changes, please have a look.

[tdruez]

@aayushkdev thanks for the changes, we are getting closer but the JSON output is still invalid. See the comment for suggestions.

Also on a more general note: avoid tempering with the git history by merging all previous commits and force-pushing in the branch, this makes looking at the code diffs since the last review much harder.
All the commits will be merged into a single commit once the PR is done, no need to rewrite history during the developement phase.

[aayushkdev]

Hey @tdruez I have made the required changes please have a look

[tdruez]

@aayushkdev Everything looks good! Could you add a simple entry in the CHANGELOG.rst file so I can merge the PR?

[aayushkdev]

@aayushkdev Everything looks good! Could you add a simple entry in the CHANGELOG.rst file so I can merge the PR?

done!!

I have also rebased the commits into one

[tdruez]

I have also rebased the commits into one

@aayushkdev As mentioned earlier, you never need to do this, and should never force-push. It's valuable to keep the commit history.
The merge into main is done as a "Squash and merge", which appears as a single commit in the main branch, but we want to keep each single development commit untouched.

[tdruez]

@aayushkdev Thanks for your contribution! But keep in mind, if you force-push, you are doing it wrong ;)

[aayushkdev]

I have also rebased the commits into one

@aayushkdev As mentioned earlier, you never need to do this, and should never force-push. It's valuable to keep the commit history. The merge into main is done as a "Squash and merge", which appears as a single commit in the main branch, but we want to keep each single development commit untouched.

Ah, I see - thanks for clarifying. I misunderstood and thought the final rebase was expected. I’ll make sure not to force-push or squash commits like this again. Appreciate the guidance!

[tdruez]

@aayushkdev No worries. Thanks for this super useful feature!