WIP: Translatable mixin continued

[maerteijn]

This is a continuation of the abandoned pull request #155

I'll add documentation and other fixes to this branch. We are testing this in a project now as well.

Things to do:

• [ ] Make TranslatablePage model configurable with a setting and use that in wagtailtrans
• [ ] Add docs about the TranslatablePageMixin and how to make your own translatable types

Update and explanation: We've been playing around a bit and this pull request can be a good start for two wagtailtrans improvements:

• The possibility to create a custom TranslatablePage model which just inherits from Page and Translatable (Page) Mixin
• Make snippets and other models translatable.

But the PR implementation is not polished enough to implement both correctly.

The current setup of wagtailtrans is depending heavily on TranslatablePage queries:

• https://github.com/wagtail/wagtailtrans/blob/9899b234b2db48eca0d3953a78d1045247002434/src/wagtailtrans/forms.py#L10
• https://github.com/wagtail/wagtailtrans/blob/9899b234b2db48eca0d3953a78d1045247002434/src/wagtailtrans/views/translation.py#L22
• https://github.com/wagtail/wagtailtrans/blob/a7e73e62559ddc1c45e8507e0929db36de96d060/src/wagtailtrans/utils/language_switch.py#L14

This makes sense as pages are stored in a tree and other objects (like snippets are not) and how it's solved now.

So I suggest that this pull request should focus on the first improvement (Create a own TranslatablePage model with just inheriting from Page and TranslatablePageMixin).

Therefore we need to make the TranslatablePage model pluggable, just like the WAGTAILIMAGES_IMAGE_MODEL in wagtail with a setting. Then we could use this mechanism to use own Page models with the Mixin.

Therefore I would rename the mixin to TranslatablePageMixin so it's more clear what it is doing.

The second step is to make snippets and other objects translatable, but that could be a next step feature in another pull request.

@mikedingjan Your thoughts on this?

[maerteijn]

Closed pull request due to lack of interest