Question

I have the following within a form_for:

  = form_for @activity do |f|
    .field
      = label :comment, :comment
      = text_area :comment, :comment, :rows => 4

I am not calling f.label or f.text_area because comment is a separate model and I am saving it separately. The above code works fine, but when the validation fails on @activity, then the comment gets wiped out. I would like for the comment field to repopulate when the @activity validation fails, so I tried the following:

  = form_for @activity do |f|
    .field
      = label :comment, :comment
      = text_area :comment, :comment, :value => @comment, :rows => 4

With this line in the controller action:

@comment = Comment.new(params[:comment][:comment])

With this, however, I get the following error:

undefined method `stringify_keys' for "hello":String

It is failing on the @comment assignment in the controller which I show above.

What is going on here?

The params after the error contain the following:

 "comment"=>{"comment"=>"hello"}

Answer 1

The problem is that Comment#new expects a Hash whose keys correspond to Comment’s attributes but you’re giving it params[:comment][:comment], whose value is a string (in this case, "hello"). I suspect that this is what you want instead:

@comment = Comment.new params[:comment]