Nested routes undefined variable Rails

Question

I am trying to build nested routes and as mentioned here I m trying to edit my boat picture as <%= link_to "edit", edit_boat_picture_path(@boat, picture) %>. But when I try it, it throws an error undefined local variable or methodpicture' for #<#:0x007f9637811ee0>`

my picture controller is; (probably destroy is wrong also)

class PicturesController < ApplicationController
  before_action :logged_in_user
  before_filter :load_parent

  def index
    @picture = @boat.pictures.all
  end

  def new
    @picture = @boat.pictures.new
  end

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


  def create

    @picture = @boat.pictures.new(picture_params)
    if @picture.save
      #flash[:success] = "Continue from here"
      render 'show'
    else
      render 'new' 
    end
  end

  def edit
    @picture = Picture.find(params[:id])
  end

  def update
    @picture = @boat.pictures.find(params[:id])

    if @picture.update_attributes(picture_params)
      flash[:notice] = "Successfully updated picture."
      render 'show'
    else
      render 'edit'
    end
  end

  def destroy

    @picture = @boat.pictures.find(params[:id])
    @picture.destroy
    flash[:notice] = "Successfully destroyed picture."
    redirect_to @picture.boat
  end


  private

    def picture_params
      params.require(:picture).permit(:name, :image)
    end

    def load_parent
     @boat = Boat.find(params[:boat_id])
    end

end

Joe Kennedy · Accepted Answer · 2015-04-21 15:26:08Z

2

Presumably you should change

<%= link_to "edit", edit_boat_picture_path(@boat, picture) %>

to

<%= link_to "edit", edit_boat_picture_path(@boat, @picture) %>

The key there being changing picture to @picture. The reason to do this is that you're declaring @picture (an instance variable) in your controller, not picture (a local variable). When declaring and defining an instance variable in a method in your controller, it's also accessible in the corresponding view. However, when declaring a local variable in a method in your controller, it is not available in your view.

So even if you had declared picture rather than @picture in your controller method, it wouldn't be accessible in your view, since it's a local variable.

For more information on the five types of ruby variables, see this link.

edited Apr 21, 2015 at 15:26

answered Apr 21, 2015 at 15:17

Joe Kennedy

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3 Comments

Shalafister Over a year ago

Yes it works that way, I tried. But did not understand the logic behind it.

Joe Kennedy Over a year ago

I edited my answer to add some explanation, does it help at all?

MrYoshiji Over a year ago

You defined @picture in the controller's action, but you were trying to acces to the picture variable, which does not exist. @variables are shared between the controller's action(s) and the view(s), whereas variables are just local variables, only existing in the local context (controller's action OR a single view OR a single block, etc.)

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