I take it you're not using `standard_create` here because you want to explicitly set the `application` and `user` members after the `consume!` call?  

Since this will probably happen fairly often, would it be reasonable to change `standard_create` and `standard_nested_create` in OSU to take a block whose purpose is to change values on the created model object?

Where these lines in `standard_nested_create`:

    model_klass.transaction do 
      consume!(@model, represent_with: get_representer(represent_with, @model))
      raise SecurityTransgression unless current_user.can_create?(@model)
    end

would look something like:

    model_klass.transaction do 
      consume!(@model, represent_with: get_representer(represent_with, @model))
      yield @model
      raise SecurityTransgression unless current_user.can_create?(@model)
    end

and the call to `standard_create` would look like:

    standard_create(ApplicationUser, Api::V1::ApplicationUserRepresenter) do |application_user|
      application_user.application = current_user.application
      application_user.user = user
    end

?