Resources from isolated engines cannot be saved

[sindrenm]

When calling param_key on an ActiveModel::Name that wraps a resource from an isolated engine, it will strip off the namespace for that engine. Because of this, it is important that ActiveAdmin uses the ActiveAdmin::Resource::Name#param_key proxy everywhere it needs the param key.

Now, 8872d84 claims to fix something, but I have to admit that I don't really understand what is being fixed. In any case, it breaks forms using resources from isolated engines.

As an example, say I have an isolated engine called Blog. It has a model called Post. Then, due to the way isolated engines work, this happens:

Blog::Post.model_name.param_key # => "post"

So, according to Rails, this is correct, but the controller for the Blog::Post resource will expect parameters for a resource called blog_post, not post and be unable to create/update the resource.

Note that this is specific to isolated engines. For a resource that has been defined in the main application, everything works fine (because ActiveModel::Naming doesn't remove the namespace on param_key). So if I define a Zoo namespace with a Zebra model in it (in the main app), it works as expected:

Zoo::Zebra.model_name.param_key # => "zoo_zebra"

[timoschilling]

I'm going to close this, while the sense of a isolated engine is that the models are isolated from the app.

Eventual it will help your to try the usage of inherited_resources#defaults.

[timoschilling]

@seanlinsley proposed a solution on a similar problem #3161 (comment)