Improve IncorrectLookupParameters admin error message

[Tim Schilling]

This is based on leunga1000's ​PR. The ModelAdmin.changelist_view's handling of IncorrectLookupParameters presents a page title of "Database error" for the particular exception of IncorrectLookupParameters. Since the user is already past authentication and authorization, we should give them more information that the querystring had an error. I would suggest "Incorrect lookup" or "Incorrect lookup in query string" depending on how technical we want to get.

I agree with leunga1000's assessment that this message is a bit cryptic and think we should make a change.

[Md. Saikat Islam]

Seems valid issue. The error message should be improved. I am taking it.

[Md. Saikat Islam]

PR is ready for this ticket: ​https://github.com/django/django/pull/21899

[Jacob Walls]

I'm having a a ​Chesterton's Fence doubt here. The code comment says "the 'invalid=1' parameter was already in the query string", so does anyone know why this was regarded as a database error before?

[Md. Saikat Islam]

the changelist_view uses creates a get_changelist_instance and that method calls many methods inside ChangeList class in view/main.py. I inspected that, inside these two files most of the times we have raised IncorrectLookupParameters error, for e.g FieldDoesNotExist, ValueError.

Heres my anaylisis on this, when we first catch the IncorrectLookupParameters we consider it the users fault, and pass a flag (value is actually 'e=' in code, the comment is stale to have 'invalid='. And after a fresh redirect, when we again has IncorrectLookupParameters error, we are sure that, its not problem in request params, its maybe our raised errors.

So, I am now confidence that the "database error" is not correct. Best, we use "Server error" in when we have error after the flag set.

[Jacob Walls]

Saikat has done a great job being responsive to feedback. On their PR, I just requested a test case that shows the error condition that would actually render this 20-year old template. If we can't find one, we should close as needsinfo or possibly repurpose this ticket to remove the template (which is ​untested).

Without knowing if the error condition is realistic we can't take a decision about how careful to be about invalidating translations.

[Jacob Walls]

Original reporter doesn't remember in enough detail how they rendered this template for us to be able to add a realistic test demonstrating some value.