Rails 4, ActiveAdmin, and acts_as_taggable_on

Rails 4 has done away with using attr_accessible and others like it. The new standard is to use strong parameters, and it definitely seems like a more secure system. But, for legacy apps upgrading to Rails 4, there is a gem called "protected_attributes" that gives you back what Rails 3 and before let you do -- which is the ability to use attr_accessible :attr1, :attr2, etc to mass assign attributes in your model. This, however, does not come without issues.

Recently I sought out to use the acts_as_taggable_on gem. I'm also using ActiveAdmin. For some reason, when I added tags to my database entries via ActiveAdmin, no errors were returned, but the entries weren't being updated. In the Rails server error logs, I found a mass assign error.

WARNING: Can't mass-assign protected attributes for ActsAsTaggableOn::Tag: name

Now, to use the acts_as_taggable_on gem, you are to use attr_accessible :tag_list in the model. But, this doesn't quite work since you're relying on the protected_attributes gem. One work around is to hack the acts_as_taggable system a bit to include those extra attributes on the attr_accessible list. But I'd rather have a future proof solution where I'm not relying on a gem for an old feature. So, I removed the protected_attributes gem from my Gemfile. And then came the long list of errors specific to Rails 4 and the new strong parameter system.

`attr_accessible': `attr_accessible` is extracted out of Rails into a gem. Please use new recommended protection model for params(strong_parameters) or add `protected_attributes` to your Gemfile to use old one.

So now I need a way to make ActiveAdmin use strong parameters instead of relying on attr_accessible. The solution is rather cumbersome, but seems the most future proof, and the most proper way to go about fixing this ActiveAdmin limitation.

In your ActiveAdmin controllers app/admin/model_name.rb, you must add the following code to each:

ActiveAdmin.register ModelName do
  controller do
    def permitted_params

The params.permit! allows all attributes to be edited. This is, after all, my admin panel. But alternatively, you can just list the specific attrs.

params.permit(:blog => [:name, :description])

And that's it! You're now using the new strong parameters with ActiveAdmin, and your acts_as_taggable_on gem works perfectly

If you run into any problems, please feel free to contact me and I'll update this article to reflect any other cases

Credit to these Stack Overflow & Github threads.
How to get ActiveAdmin to work with Strong Parameters?
Rails 4 protected attributes
Saving tags with acts_as_taggable and activeadmin