Rails Generates Blank Record Even Input Data

Question

I am learning to use CRUD, and setup a page to add a record, however it only generated blank record? Can you take a look my code?

thanks!

here is the Page controller:

class PagesController < ApplicationController
   def index
    @test = Page.all
  end

  def new
    @test = Page.new
  end

  def create
    @test = Page.new(params.permit(:subject_id,:name,:position,:visible,:permalink))
    if @test.save
      flash[:notice] = "Page created successfully!"
      redirect_to(:action => 'index')
    else
      render('new')
    end
  end

end

here is the new.html.erb

<%= link_to("<< Back to List", {:action => 'index'}, :class => 'back-link') %>

<div class="pages new">
  <h2>Create Subject</h2>

  <%= form_for(:Page, :url => {:action => 'create'}) do |f| %>

    <table summary="Page form fields">
     <tr>
        <th>Subject_ID</th>
        <td><%= f.text_field(:subject_id) %></td>
      </tr>
      <tr>
        <th>Name</th>
        <td><%= f.text_field(:name) %></td>
      </tr>
      <tr>
        <th>Position</th>
        <td><%= f.text_field(:position) %></td>
      </tr>
      <tr>
        <th>Visible</th>
        <td><%= f.text_field(:visible) %></td>
      </tr>
       <tr>
        <th>Permalink</th>
        <td><%= f.text_field(:permalink) %></td>
      </tr>
    </table>

    <div class="form-buttons">
      <%= submit_tag("Create Subject") %>
    </div>

  <% end %>
</div>

Here is index.html.erb

<div class="pages index">
  <h2>Pages</h2>

 # <%= link_to("Add New Page", {:action => 'new'}, :class => 'action new') %>

  <table class="listing" summary="Page list">
    <tr class="header">
      <th>Position</th>
      <th>Page Name</th>
      <th>Visible</th>
      <th>Pages</th>
      <th>Actions</th>
    </tr>
    <% @test.each do |f| %>
    <tr>
      <td><%= f.position %></td>
      <td><%= f.name %></td>
      <td class="center"><%= f.visible %></td>
      <td class="center"><%= f.permalink %></td>
      <td class="actions">
        <%= link_to("Show", {:action => 'show', :id => f.id}, :class => 'action show') %>
        <%= link_to("Edit", {:action => 'edit', :id => f.id}, :class => 'action edit') %>
        <%= link_to("Delete", {:action => 'delete', :id => f.id}, :class => 'action delete') %>
      </td>
    </tr>
    <% end %>
  </table>
</div>

Thanks so much!

params.require(:page).permit(:subject_id,:name,:position,:visible,:permalink) — AbM
– AbM, Commented Jun 22, 2015 at 23:06

max · Accepted Answer · 2015-06-22 23:26:06Z

1

Strong parameters

Rails sends form parameters in nested hashes.

{ page: { subject_id: 1, name: 'Hello World.' } }

So to whitelist the parameters you would do.

class PagesController < ApplicationController
   def index
    @test = Page.all
  end

  def new
    @test = Page.new
  end

  def create
    @test = Page.new(page_params)
    if @test.save
      flash[:notice] = "Page created successfully!"
      redirect_to(:action => 'index')
    else
      render('new')
    end
  end

  private 

  def page_parameters
    params.require(:page)
          .permit(:subject_id,:name,:position,:visible,:permalink)
  end
end

which is like doing:

params[:page].slice(:subject_id,:name,:position,:visible,:permalink)

form_for and models

Also your form should read:

 <%= form_for(:page, :url => {:action => 'create'}) do |f| %>

Or:

 <%= form_for(@page, :url => {:action => 'create'}) do |f| %>

:Page will give you the wrong key in your parameters and prevent rails from binding the form to your @page object. (The values posted will disappear from the form when it's invalid).

edited Jun 22, 2015 at 23:26

answered Jun 22, 2015 at 23:19

max

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3 Comments

ray Over a year ago

thanks so much, maxcal! why I should use "page" instead of "Page"?

max Over a year ago

Because form_for(:page) looks for the instance variable @page, form_for(:Page) would look for @Page which is not defined. Ruby like most sensible programming languages is case sensitive.

ray Over a year ago

thanks agin, maxcal! now I understood the difference :)

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Strong parameters

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