Héctor Espinoza Héctor Espinoza - 4 months ago 7
Ruby Question

How to insert multiselect in a join table

Pressing the submit button returns the following error:

NoMethodError in AuthorsController#create
undefined method `name' for Authorbook:0x007fe6e4284b28


and the parameters of the request:

Parameters:

{"utf8"=>"✓",
"authenticity_token"=>"/86GsyhAODP55TYKftsW64Lx1Quy5t/hfthlhG9bcto5+B9CwjejJGcMJyr5+IEpA8xi7FehmSv4cMNxvvadUg==",
"author"=>{"name"=>"hector"},
"books"=>{"id"=>["",
"2",
"3"]},
"commit"=>"Create Author"}


I do not know what happens, apparently the controller receives the name of the author as a parameter and can't handle it.

Models:

class Author < ActiveRecord::Base
validates :name, :presence => true
has_many :authorbooks
has_many :books, :through => :authorbooks
end

class Authorbook < ActiveRecord::Base
validates :name, :presence => true
belongs_to :book
belongs_to :author
end

class Book < ActiveRecord::Base
validates :name, :presence => true
has_many :authorbooks
has_many :authors, :through => :authorbooks
end


Controller:

class AuthorsController < ApplicationController
before_action :set_author, only: [:show, :edit, :update, :destroy]

# GET /authors
# GET /authors.json
def index
@authors = Author.all
end

# GET /authors/1
# GET /authors/1.json
def show
end

# GET /authors/new
def new
@author = Author.new

@all_books = Book.all

@author_book = @author.authorbooks.build
end

# GET /authors/1/edit
def edit
end

# POST /authors
# POST /authors.json
def create
@author = Author.new(author_params)

params[:books][:id].each do |book|
if !book.empty?
@author.authorbooks.build(:book_id => book)
end
end

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

# PATCH/PUT /authors/1
# PATCH/PUT /authors/1.json
def update
respond_to do |format|
if @author.update(author_params)
format.html { redirect_to @author, notice: 'Author was successfully updated.' }
format.json { render :show, status: :ok, location: @author }
else
format.html { render :edit }
format.json { render json: @author.errors, status: :unprocessable_entity }
end
end
end

# DELETE /authors/1
# DELETE /authors/1.json
def destroy
@author.destroy
respond_to do |format|
format.html { redirect_to authors_url, notice: 'Author was successfully destroyed.' }
format.json { head :no_content }
end
end

private
# Use callbacks to share common setup or constraints between actions.
def set_author
@author = Author.find(params[:id])
end

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


and the _form:

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

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

<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %>
</div>

<%= fields_for (@author_book) do |ab| %>
<div class="field">
<%= ab.label "All Books" %> <br>
<%= collection_select(:books, :id, @all_books, :id, :name, {}, {:multiple => true}) %>
</div>
<% end %>

<div class="actions">
<%= f.submit %>
</div>
<% end %>

Answer

Just remove the

validates :name, :presence => true #Authorbook    

in "Authorbooks", because your model doesn't have that field, so basically you are just asking Rails to validate a field that doesn't exist.

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