CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-4
Pacane
Pacane

Reputation: 21471

param not found in form_for

I've made a little test with Rails scaffolding, and I tried to generate a controller and a view for an already existing model.

I'm trying to edit a value for my model.

In the controller all the requires methods are there, and there's even :

# Never trust parameters from the scary internet, only allow the white list through.
def tag_params
    params[:tag]
end

The only value I tried to update from my model (named Tag) was :name, so I edited the tag_params method to look like this:

# Never trust parameters from the scary internet, only allow the white list through.
def tag_params
    params[:tag].require(:tag).permit(:name)
end

as I usually do, but now I get a param not found: tag exception.

However, if I write it like this 

# Never trust parameters from the scary internet, only allow the white list through.
def tag_params
    params[:tag].permit(:name)
end

it works alright. Why is that?

The form_for declaration in the view looks like this:

<%= form_for(@tag) do |f| %>

For those who don't know how scaffolding method look like in the controller, here's a part of it :

 # GET /tags/1/edit
  def edit
  end

  # PATCH/PUT /tags/1
  # PATCH/PUT /tags/1.json
  def update
    respond_to do |format|
      if @tag.update(tag_params)
        format.html { redirect_to tags_path, notice: 'Tag was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @tag.errors, status: :unprocessable_entity }
      end
    end
  end

  private
    # Never trust parameters from the scary internet, only allow the white list through.
    def tag_params
        params[:tag]
    end

Upvotes: 0

Views: 123

Answers (2)

aromero
aromero

Reputation: 25761

params[:tag].require(:tag) will require a param tag inside the params[:tag] hash. What you want to do is params.require(:tag).permit(:name).

Upvotes: 1

Hesham
Hesham

Reputation: 2347

It should be:

def tag_params
  params.require(:tag).permit(:name)
end

Upvotes: 1

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