Question

Rails newbie working on associating tasks with lists and running into trouble when I try and interact with forms after I start the rails server.

Here’s the error I’m getting. Any ideas?

Thanks!

NoMethodError in TasksController#create

undefined method `find_or_create_by_name' for #<Class:0x00000102a8bad0>
Rails.root: /Users/user/rails_projects/todolist

Application Trace | Framework Trace | Full Trace
app/models/task.rb:15:in `list_name='
app/controllers/tasks_controller.rb:43:in `new'
app/controllers/tasks_controller.rb:43:in `create'
Request

Parameters:

{"utf8"=>"✓",
 "authenticity_token"=>"B7g7u+v5USPRhefdFPt84xGkKjB1nVwy62IJj6SHJpc=",
 "task"=>{"description"=>"Milk",
 "list_name"=>"Shopping"},
 "commit"=>"Create Task"}

ListsController:

class ListsController < ApplicationController

      # GET /lists
      # GET /lists.json
      def index
      @lists = List.all

      respond_to do |format|
        format.html # index.html.erb
        format.json { render json: @lists }
      end
    end

    # GET /lists/1
    # GET /lists/1.json
    def show
      @list = List.find(params[:id])

      respond_to do |format|
        format.html # show.html.erb
        format.json { render json: @list }
      end
    end

    # GET /lists/new
    # GET /lists/new.json
    def new
      @list = List.new

      respond_to do |format|
        format.html # new.html.erb
        format.json { render json: @list }
      end
    end

    # GET /lists/1/edit
    def edit
      @list = List.find(params[:id])
    end

    # POST /lists
    # POST /lists.json
    def create
      @list = List.new(params[:list])

      respond_to do |format|
        if @list.save
          format.html { redirect_to @list, notice: 'List was successfully created.' }
          format.json { render json: @list, status: :created, location: @list }
        else
          format.html { render action: "new" }
          format.json { render json: @list.errors, status: :unprocessable_entity }
        end
      end
    end

    # PUT /lists/1
    # PUT /lists/1.json
    def update
      @list = List.find(params[:id])

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

    # DELETE /lists/1
    # DELETE /lists/1.json
    def destroy
      @list = List.find(params[:id])
      @list.destroy

      respond_to do |format|
        format.html { redirect_to lists_url }
        format.json { head :no_content }
      end
    end
  end

TasksController:

class TasksController < ApplicationController

      # GET /tasks
      # GET /tasks.json
      def index
      @tasks = Task.all

      respond_to do |format|
       format.html # index.html.erb
       format.json { render json: @tasks }
    end
  end

  # GET /tasks/1
  # GET /tasks/1.json
  def show
    @task = Task.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @task }
    end
  end

  # GET /tasks/new
  # GET /tasks/new.json
  def new
    @task = Task.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @task }
    end
  end

  # GET /tasks/1/edit
  def edit
    @task = Task.find(params[:id])
  end


  # POST /tasks
  # POST /tasks.json
  def create
    @task = Task.new(params[:task])

    respond_to do |format|
      if @task.save
        format.html { redirect_to @task, notice: 'Task was successfully created.' }
        format.json { render json: @task, status: :created, location: @task }
      else
        format.html { render action: "new" }
        format.json { render json: @task.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /tasks/1
  # PUT /tasks/1.json
  def update
    @task = Task.find(params[:id])

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

  # DELETE /tasks/1
  # DELETE /tasks/1.json
  def destroy
    @task = Task.find(params[:id])
    @task.destroy

    respond_to do |format|
      format.html { redirect_to tasks_url }
      format.json { head :no_content }
    end
  end
end

Task model:

class Task < ActiveRecord::Base

    attr_accessible :description, :list_name

    belongs_to :list, :foreign_key => "list_id" 

   def name
      @list = List.find(params[:id])
    end

    def list_name
      list.name if self.list 
    end

    def list_name=(str)
      self.list = List.find_or_create_by_name(str) 
    end

  end

List model:

class List < ActiveRecord::Base

    attr_accessible :title
    has_many :tasks 

    def name
      @list = List.find(params[:id])
    end

  end

Partial for Tasks:

    <%= form_for(@task) do |f| %>
    <% if @task.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@task.errors.count, "error") %> prohibited this task from being        saved:</h2>

      <ul>
      <% @task.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :description %><br />
    <%= f.text_area :description %>
  </div>
  <div class="field">
    <%= f.label :list_name %><br />
    <%= f.text_field :list_name %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Partial for Lists:

   <%= form_for(@list) do |f| %>
    <% if @list.errors.any? %>
      <div id="error_explanation">
        <h2><%= pluralize(@list.errors.count, "error") %> prohibited this list from being saved:</h2>

        <ul>
        <% @list.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
        </ul>
      </div>
    <% end %>

    <div class="field">
      <%= f.label :title %><br />
      <%= f.text_field :title %>
    </div>
    <div class="actions">
      <%= f.submit %>
    </div>
  <% end %>

Answer 1

Rails’ dynamic finders (find_by_... and find_or_create_by_...) are generated using the attributes of a model. You were using find_or_create_by_name when name wasn’t an attribute on the List model.

Changing that to find_or_create_by_title(...) fixes the problem.