custom js for action form also handles grappelli

[frnhr]

ExportActionModelAdmin works fine with Django-Grappelli except for one little detail: on valila admin, there is a little jQuery snippet that toggles visibility of the added file_format field. Because Grappelli uses different CSS classes and IDs, this toggling does not occur.

This in vanila admin:

... looks like this in grapppelli:

... but in the default state looks like this:

Changes in this PR enable grappelli to benefit from the existing feature in the same way that vanila django-admin does, by hiding the second dropdown in grappelli until the "export" action is selected. Original functionality in vanila admin is not affected.

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Contributing guidelines... yes I have read them. Cannot comply to most of the requirements there because they assume changes to Python code. Please let me know if I should comply to some. Happy to. Also happy if this gets merged in as is :)

In order to be merged into django-import-export, contributions must have the following:

• A solid patch that:
  • is clear.
  • works across all supported versions of Python/Django.
  • follows the existing style of the code base (mostly PEP-8).
  • comments included as needed to explain why the code functions as it does
• A test case that demonstrates the previous flaw that now passes with the included patch.
• If it adds/changes a public API, it must also include documentation for those changes.
• Must be appropriately licensed (see Philosophy).
• Adds yourself to the AUTHORS file.
  If your contribution lacks any of these things, they will have to be added by a core contributor before being merged into django-import-export proper, which may take substantial time for the all-volunteer team to get to.

[coveralls]

Coverage remained the same at 91.276% when pulling 70f236f on frnhr:action_form_on_grappelli into d0157e2 on django-import-export:master.

[bmihelac]

Hi @frnhr and thanks for your contribution.

Even we do not support various admin themes, I see this as usable and unobtrusive change. I'll merge unless there are objections from other maintainers.

[manelclos]

Haven't tested but LGTM

[bmihelac]

merged, thanks!