Rails unable to access instance variable in .js.erb file

Question

I'm making an ajax request and when it's complete i'm trying to add a div to the page. For some reason, i am unable to get instance variables to work in a .js.erb file.

I have this controller method that gets called

 # PUT /applications/1
  # PUT /applications/1.json
  def update
    @application = Application.find(params[:id])
    @current_app = params[:application]
    @curr_app_id = params[:id]
    @current_app.values.each do |key, val|
        key.values.each do |k,v|
            @curr_app_field_name = k[:field_name]
            @curr_app_field_value = k[:field_type]
        end
    end

    respond_to do |format|
      if @application.update_attributes(params[:application])
        format.html { redirect_to @application, notice: 'Application was successfully updated.' }
        format.json { head :no_content }
        format.js
      else
        format.html { render action: "edit" }
        format.json { render json: @application.errors, status: :unprocessable_entity }
        format.js
      end
    end
  end

which renders this .js.erb file

console.log('name = '+<%= escape_javascript @curr_app_field_name %>); // line 1
console.log('test'); // line 2

But when i leave the instance variable in there, i don't get any output in firebug. I can see in the post request that the console.logs get generated with the correct field name, but nothing appears in the firebug console.

If i remove line 1 completely, it works.

How can i make it so i can access some variables in a .js.erb file?

You are currently overriding the @curr_app_field_name in loop. Try to inspect whether the last element in the loop is not blank or nil — shivashankar
– shivashankar, Commented Dec 7, 2012 at 14:21

Mischa · Accepted Answer · 2012-12-07 06:48:17Z

6

You are mixing Javascript and Ruby incorrectly.

Instead of:

console.log('name = '+<%= escape_javascript @curr_app_field_name %>);

you have to do this:

console.log('name = <%= escape_javascript @curr_app_field_name %>');

Explanation:

Suppose @curr_app_field_name == 'foo' then your current code will evaluate to:

console.log('name = '+foo);

but the variable foo doesn't exist and will therefore throw an error. If you do it like I suggest it will evaluate to:

console.log('name = foo');

and everything will work as expected.

edited Dec 7, 2012 at 6:48

answered Dec 7, 2012 at 6:38

Mischa

43.4k9 gold badges101 silver badges111 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

muloka Over a year ago

This also works console.log('name = '+ <%= raw @curr_app_field_name) Especially useful if you want to do something like: console.log('name = '+ <%= raw JSON.dump(@application.errors) %>)

Jonathan Vukovich-Tribouharet · Accepted Answer · 2012-12-07 06:41:47Z

0

I think you have to add quotes like this:

console.log('name = '+ "<%= escape_javascript @curr_app_field_name %>");

But if it was just that you may have an error in firebug.

answered Dec 7, 2012 at 6:41

Jonathan Vukovich-Tribouharet

1,98814 silver badges17 bronze badges

Collectives™ on Stack Overflow

Rails unable to access instance variable in .js.erb file

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related