Datamapper compatibility

[shingara]

Datamapper is not compatible to nested_form.

To have the accepts_nested_attributes_for in Datamapper you need use the gem : dm-accepts_nested_attributes.

But if you use it, nested_form is not compatible because 2 problems :

1. reflect_on_association

This method is not design in Datamapper. You need use the klass.repository[association].target_model instead.

2. _destroy is not define

In this gem the attribute to mark a record destroy is _delete instead of _destroy on ActiveRecord. And there are no method _destroy or _delete in the instance to check if this object can be delete or not in futur.

This pull request help to work DataMapper and nested_form together. But actually, it's not compatible to ActiveRecord anymore. I can do the job to be compatible both. But I prefer start avoid it in first and do the job if needed.

[shingara]

Spec failed because this incompatibility.

[lest]

I think we should think about extracting ActiveRecord dependent code into a module at first. Then we could easily add DataMapper or any other ORM compatibility.