Question

    My Application name is LibraryWebApplication when I accessing my new.erb file using /books/new its giving the form then I filled the form with title,price,description then I clicked the button create its is going to following url /books/create but its is not storing data into data base its showing the following error 

    LoadError in BooksController#create

    Unable to autoload constant BooksController, expected D:/RailsAppsExamples/LibrarayWebApplication/app/controllers/books_controller.rb to define it

    the stack trace is 

    tarted POST "/books/create" for 127.0.0.1 at 2014-03-18 16:24:39 +0530

    LoadError (Unable to autoload constant BooksController, expected D:/RailsAppsExamples/LibrarayWebApplication/app/controllers/books_controller.rb to define it):
      activesupport (4.0.3) lib/active_support/dependencies.rb:464:in `load_missing_constant'
      activesupport (4.0.3) lib/active_support/dependencies.rb:184:in `const_missing'
      actionpack (4.0.3) lib/action_dispatch/routing/route_set.rb:680:in `call'
      rack (1.5.2) lib/rack/etag.rb:23:in `call  

    I have two models

    book.rb

        class Book < ActiveRecord::Base
            belongs_to :subject
            validates_presence_of :title
          validates_numericality_of :price, :message=>"Error Message"
        end

    subject.rb

        class Subject < ActiveRecord::Base
            has_many :books
        end

What is mean by Unable to auto load constant Books Controller I am helpless to find/detect the problem in my application
  I used Strong Parameters as I am using Rails4 and I am new to ruby and rails
    is it require to write the Strong Parameters..is to match the permit parameters with database tables parameters

my controller is

        books_controller.rb
    class BookController < ApplicationController
       def list
          @books = Book.find(:all)
       end
       def show
          @book = Book.find(params[:id])
       end
       def new
          @book = Book.new
          @subjects = Subject.find(:all)
       end
       def create
          @book = Book.new(params[:book])
          if @book.save
                redirect_to :action => 'list'
          else
                @subjects = Subject.find(:all)
                render :action => 'new'
          end
       end
        private
        def book_params
          params.require(:book).permit(:title,:price)
        end

       def edit
          @book = Book.find(params[:id])
          @subjects = Subject.find(:all)
       end
       def update
          @book = Book.find(params[:id])
          if @book.update_attributes(params[:book])
             redirect_to :action => 'show', :id => @book
          else
             @subjects = Subject.find(:all)
             render :action => 'edit'
          end
       end
       def delete
          Book.find(params[:id]).destroy
          redirect_to :action => 'list'
       end
       def show_subjects
          @subject = Subject.find(params[:id])
       end
    end

    my routes.rb is

        LibrarayWebApplication::Application.routes.draw do
            get 'books/new'
            post 'books/create'
          get 'books/list'
           get 'books/show'
          get 'books/edit'
         get 'books/show_subjects'
        end


new.erb file is


        <h1>Add new book</h1>
        <%= form_tag :action => 'create' %>
        <p><label for="book_title">Title</label>:
        <%= text_field 'book', 'title' %></p>
        <p><label for="book_price">Price</label>:
        <%= text_field 'book', 'price' %></p>
        <p><label for="book_subject">Subject</label>:
        <%= collection_select(:book,:subject_id,@subjects,:id,:name) %></p>
        <p><label for="book_description">Description</label><br/>
        <%= text_area 'book', 'description' %></p>
        <%= submit_tag "Create" %>
        <%= link_to 'Back', {:action => 'list'} %>


migration files are


     20140318084539_books.rb

        class Books < ActiveRecord::Migration
         def self.up
             create_table :books do |t|
          t.column :title, :string, :limit => 32, :null => false
          t.column :price, :float
          t.column :subject_id, :integer
          t.column :description, :text
          t.column :created_at, :timestamp
             end
          end

          def self.down
            drop_table :books
          end
        end

    20140318084609_subjects.rb

        class Subjects < ActiveRecord::Migration
          def self.up
              create_table :subjects do |t|
               t.column :name, :string
            end
            Subject.create :name => "Physics"
            Subject.create :name => "Mathematics"
            Subject.create :name => "Chemistry"
            Subject.create :name => "Psychology"
            Subject.create :name => "Geography"
          end

          def self.down
              drop_table :subjects
          end
        end

是否需要强参数代码中的所有列名称，您能告诉我如何为我的应用程序编写强参数..我无法继续前进我有两本表和主题

    books columns are as
    follows 
    id,title,price,subject_id, Description,created_at

    and subjects table columns are
    id,name

是否需要强参数代码中的所有列名称，您能告诉我如何为我的应用程序编写强参数..我无法继续前进我有两本书和主题我无法在Books Controller中的Load Error应用程序中找到问题#create是否需要编写Strong Parameters ..来匹配permit参数和数据库表参数

Answer 1

控制器的类名是BookController而不是BooksController

BooksController #creore中的LoadError，无法自动加载常量BooksController，预期

1 个答案: