CODEWITHSUNDEEP
ruby-on-rails
mazing
mazing

Reputation: 743

Rails view unable to display form input parameters

I'm trying to build a form that has an input for a question, and five inputs, each of which represents an answer choice.

My problem is that in my /show.html.erb file, it throws an error which I can't figure out.

For instance: 

QUESTION
ANS1
ANS2
ANS3
ANS4
ANS5

Here's what I have so far:

# app/views/mcqs/new.html.erb
<%= form_for :mcq, url: mcqs_path do |f| %>

    <%= f.label :title %><br>
    <%= f.text_field :q %>

    <%= f.label :ans1 %><br>
    <%= f.text_field :ans1 %>

    <%= f.label :ans2 %><br>
    <%= f.text_field :ans2 %>

    <%= f.label :ans3 %><br>
    <%= f.text_field :ans3 %>

    <%= f.label :ans4 %><br>
    <%= f.text_field :ans4 %>

    <%= f.label :ans5 %><br>
    <%= f.text_field :ans5 %>


    <%= f.label :category_id %><br>
    <%= f.number_field :category_id %>

  <%= f.label :tags %><br>
    <%= collection_check_boxes(:mcq, :tag_ids, Tag.all, :id, :name) %>

    <%= f.submit %>

<% end %>

The controller:

# app/controllers/mcqs_controller.rb
class McqsController < ApplicationController
    def new
        @Mcq = Mcq.new
    end

    def index
        @questions = Mcq.all
    end

    def show
        @Mcq = Mcq.find(params[:id])    
    end

    def create
        @Mcq = Mcq.new(params[:mcqs])
        # @Mcq.save returns a boolean indicating whether the article was saved or not.
        if @Mcq.save 
            redirect_to @Mcq
        else
            render 'new'
        end
    end
end

The view:

# app/news/mcqs/show.html.erb
<strong>MCQ Title:</strong><br>
<%= mcq.q %>

<strong>Question Text:</strong><Br>
<%= mcq.ans1 %>

...<strong>MCQ Title:</strong><br>
<%= mcq.q %>

<strong>Question Text:</strong><Br>
<%= mcq.ans1 %>
...

The error:

NameError in Mcqs#show
Showing app/views/mcqs/show.html.erb where line #4 raised:

undefined local variable or method `mcq' for #<#
<Class:0x007fad811936e8>:0x007fad838a47a0>

<strong>MCQ Title:</strong><br>
<%= mcq.q %>
</p><p>

How can I display the input of the new.html.erb on the show.html.erb without this error?. <%= @mcq.q %> doesn't work.

Upvotes: 0

Views: 45

Answers (2)

Sebasti&#225;n Palma
Sebasti&#225;n Palma

Reputation: 33471

In your show method you create @Mcq as Mcq.find(params[:id]), but then in your show view you want to access to it as mcq, so you need to access it the same way (name) as you declared it within the controller.

Try with:

<strong>MCQ Title:</strong><br>
<%= @Mcq.q %>

If you create a @mcq on the controller (show method), and then you want to access to it in the view which responds to that method using @Mcq, then you will receive an object with NilClass, that's to say, if the names don't match, they won't work.

Also if you use @mcq on the controller, and then you want to access as mcq, that won't work neither, the one on your controller is an instance variable, available to be used within your views coming from your controllers, the second one is a local variable, and most probably it'll raise an undefined local variable or method 'variable' error.

I can quote to @Anhubaw with:

The main difference between local and instance variable is that local variable is only available in controller, where as instance variable is available in corresponding views also. The controller and views do not share local variables

Upvotes: 3

Spark.Bao
Spark.Bao

Reputation: 5753

Change all @Mcq in controller to @mcp, and change all mcq in view to @mcq, also change :mcq in new view to @mcq.

The variable prefix with @ means it is an instance variable, it can be accessible in the view, while the normal variable doesn't start with @ is just a local variable, it just can be used in the controller action method.

Upvotes: 1

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