Ruby on Rails won't render edit page without id

Question

For some reason the edit action won't render i get this error and is using show action instead of edit but the same form works for the render :new action

• do not focus on the params[:preview], i am talking about the last render :edit

ActionController::UrlGenerationError in Admin::Blog::Posts#update No route matches {:action=>"show", :controller=>"admin/blog/posts", :id=>""} missing required keys: [:id]

def edit
    @post = Post.find_by_permalink(params[:id])
  end

def update
    @post = Post.find_by_permalink(params[:id])
    if params[:publish]
      @post.publish
    elsif params[:draft]
      @post.draft
    end

    if params[:preview]
      if @post.published?
        @post.draft
      end

      if @post.update(blog_post_params)
        flash[:success] = "some text "

        redirect_to blog_post_url(@post)
      else
        render :edit
      end
    end
    if @post.update(blog_post_params)
      flash[:success] = "Post was successfully updated."
      redirect_to edit_admin_blog_post_url(@post)
    else
      render :edit
    end

  end

form

<%= form_for [:admin,:blog, @post] do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="large-12 columns">
    <div class="field panel">
      <%= f.label :title %><br>
      <%= f.text_field :title %>
    </div>
    <div class="field panel">
      <%= f.label :description %><br>
      <%= f.text_field :description %>
    </div>
    <div class="actions panel text-right">
      <% if @post.published? %>
        <%= f.submit "Save Changes",name: "publish", class: "tiny button radius success" %>
      <% else %>
        <%= f.submit "Publish",name: "publish", class: "tiny button radius success" %>
      <% end %>

      <%= f.submit 'Mark as Draft', name: "draft", class: "tiny button radius " %>
      <% if @post.created_at %>
        <%= f.submit 'Preview', name: "preview", class: "tiny button radius warning" %>
      <% end %>
      <%= link_to 'Back', admin_blog_posts_path, class: "tiny button radius secondary" %>
    </div>
    <div class="field panel">
      <%= f.label :body %><br>
      <%= f.cktext_area :body, :height => '800px', :id => 'sometext' %>
    </div>




  </div>

<% end %>

relevant routes

namespace :admin do
     namespace :blog do
          get '', to: 'welcome#index', as: '/'
          resources :posts
     end
end

post model

class Post < ActiveRecord::Base
  has_many :tags
  has_many :comments
  before_validation :generate_permalink
  validates :permalink, uniqueness: true
  validates :title, presence: true
  validates :description, presence: true


  def generate_permalink
    self.permalink = title.parameterize
  end

  def to_param
    permalink
  end

end

Answer 1

I guess i know why you get this error.

In the edit action you use Post.find_by_permalink(params[:id]) to find your post, which returns nil if nothing was found. And since you may change the title attribute, your permalink is updated (i guess), and your post is not found. The controller still renders the action, with nil @post , and cannot generate the url for the form.

Try using Post.find_by_permalink!(params[:id]) instead, and you will get a 404.

I would actually suggest you to use regular find in the admin area, since the permalink might change.