Add support to has_many form building with draper

[ready4god2513]

When using draper to decorate, building forms with has_many fields does not work correctly as the class is not a model, but a draper wrapped object. Draper provides a method called "model_class" which will return the wrapped object class.

[ready4god2513]

I am working on a fix for this right now and should have a pull request once I go through all the steps in the contribution guide.

[amiel]

@ready4god2513 How's this coming? I was actually thinking we should not send the decorated model to the form anyway, but I'm curious what your angle on this is...

See #2013.

[seanlinsley]

@amiel given what's happened since, thoughts on this?

[amiel]

@ready4god2513 Does #2085 solve this for you? Or do you still need to handle has_many form building with decorated form objects.

I don't have need for this myself, but I do think that using decorate: false is not an obvious fix for this problem, so it should at least be documented...

@daxter you at railsconf?

[seanlinsley]

No I'm not unfortunately. I assume you are?

I'm assuming that the OP's problem is caused by this line in the has_many form builder.

Where we'd need this to deal with either situation:

obj      = has_many_form.object
resource = obj.respond_to?(:model_class) ? obj.model_class : obj
if resource.new_record?
  # ...

[ready4god2513]

I actually haven't been using active_admin for most recent projects. Sorry I couldn't be of more help.

[amiel]

@daxter thoughts? Are you ok with letting this lie until it becomes an issue?

[seanlinsley]

I'm hesitant to implement this since I haven't actually used decorators before. I'd just leave it be until someone else runs into the problem.

[amiel]

That sounds reasonable to me. I'll be happy to tackle it if it becomes an issue. Until then the decorate: false feature solves the problem for me.