I think that you’re trying to figure out creating a new associated item vs. associating with an existing item. For creating a new item, you seem to have it working. When you passed the id in shop_attributes, it did not work, because it’s looking up an association that doesn’t exist yet. If you’re trying to … Read more
This will probably work for you, but I have a feeling there’s a much better answer out there. It sounds like a bug to me. class Parent < ActiveRecord::Base validate :must_have_children def must_have_children if children.empty? || children.all?(&:marked_for_destruction?) errors.add(:base, ‘Must have at least one child’) end end end
I’ve also had a problem with the “ArgumentError: Cannot build association model_name. Are you trying to build a polymorphic one-to-one association?” And I found a better solution for this kind of problem. You can use native method. Lets look to the nested_attributes implementation, inside Rails3: elsif !reject_new_record?(association_name, attributes) method = “build_#{association_name}” if respond_to?(method) send(method, attributes.except(*UNASSIGNABLE_KEYS)) … Read more
Nested attributes appear to work fine for a belongs_to association as of Rails 4. It might have been changed in an earlier version of Rails, but I tested in 4.0.4 and it definitely works as expected.
Putting the logic in the controller could be the best answer as you stated, but you could get the after_initialize to work by doing the following: after_initialize :add_product def add_product self.product ||= Product.new end That way, it only sets product if no product exists. It may not be worth the overhead and/or be less clear … Read more
I had to add :id to the permitted params in the survey_params method. It now looks like this: # Never trust parameters from the scary internet, only allow the white list through. def survey_params params.require(:survey).permit(:name, questions_attributes: [:id, :content]) end which works perfectly. I guess new id’s were generated instead of being passed to the update … Read more
As odd as it sound when you want to permit nested attributes you do specify the attributes of nested object within an array. In your case it would be Update as suggested by @RafaelOliveira params.require(:measurement) .permit(:name, :groundtruth => [:type, :coordinates => []]) On the other hand if you want nested of multiple objects then you … Read more