Ignore empty nested attributes when using Rails Admin
How to resolve issues that arise with saving models if you have empty nested attributes using reject_if
When using Rails Admin we use accepts_nested_attributes_for to give our clients a cleaner and less complicated view. They were recently having issues with saving an instance of a model with a field which was not required. On a little more digging we discovered that they created an empty instance of a nested rails model.
To resolve this we changed our accepts_nested_attributes_for to use reject_if:
accepts_nested_attributes_for :cover_image, allow_destroy: true, reject_if: proc { |attribute| attribute[:body].blank? }
This checks to see if the body attribute (which is required in the nested model) is blank and if so rejects it meaning that the parent model can save.