ruby on rails has_many relation form validation of children

Question

I followed the tutorial to create the blog application. So I have posts and comments. The validation for fields in the posts form works perfect. The validation in the comments section of a post works as well, but I cant get the errors to be printed.

The comment model:

    class Comment 
      belongs_to :post  
      validates :commenter, :presence => true  
    end

The comment controller:

  def create
    @post = Post.find(params[:post_id])
    @comment = @post.comments.build(params[:comment])
    if @comment.save
      redirect_to post_path(@post)
    else
      render :template => 'posts/show' 
    end
end
  def destroy
    @post = Post.find(params[:post_id])
    @comment = @post.comments.find(params[:id])
    @comment.destroy
    render :template => 'posts/show'    
  end

The post controller:

  def index
    @posts = Post.all
    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @posts }
    end
  end
  def show
    @post = Post.find(params[:id])
    @comment = @post.comments.build #added
    #@comment = @Comment.new #added
    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @post }
    end
  end
  def new
    @post = Post.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @post }
    end
  end
  def edit
    @post = Post.find(params[:id])
  end
  def create
    @post = Post.new(params[:post])

    respond_to do |format|
      if @post.save
        format.html { redirect_to(@post, :notice => 'Post was successfully created.') }
        format.xml  { render :xml => @post, :status => :created, :location => @post }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @post.errors, :status => :unprocessable_entity }
      end
    end
  end
  def update
    @post = Post.find(params[:id])

    respond_to do |format|
      if @post.update_attributes(params[:post])
        format.html { redirect_to(@post, :notice => 'Post was successfully updated.') }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @post.errors, :status => :unprocessable_entity }
      end
    end
  end
  def destroy
    @post = Post.find(params[:id])
    @post.destroy
    respond_to do |format|
      format.html { redirect_to(posts_url) }
      format.xml  { head :ok }
    end
  end

And I use in the form:

<%= form_for([@post, @post.comments.build]) do |f| %>

How would I get the .errors for the comments? If I try I always get: undefined method `errors' or nil object.

Please help, I am completely new to rails.

Thanks!

Picki

What version of rails are you using?

Brett Bender
– Brett Bender

2011-03-22 20:03:32 +00:00
Commented Mar 22, 2011 at 20:03 — Brett Bender
– Brett Bender, Commented Mar 22, 2011 at 20:03

polarblau · Accepted Answer · 2011-03-23 20:16:19Z

4

The problem is, that you're building the comment new every time you're loading the form. Like this, the comment with the validation errors never makes it into your form.

Create the comment instead in your controller, something like this — details depending on your application:

# posts controller
def show
  @post = Post.find(params[:id])
  @comment = Comment.new
end

# comments controller
def create
  @post = Post.find(params[:post_id])
  @comment = @post.comments.build(params[:comment])
  if @comment.save
    redirect_to @post
  else
    render :new
  end
end

And change your form:

<%= form_for([@post, @comment]) do |f| %>

edited Mar 23, 2011 at 20:16

answered Mar 22, 2011 at 21:30

polarblau

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9 Comments

picki Over a year ago

Hello! Now I am able to get the comment.errors. Works perfect. Thanks polarblau!!

picki Over a year ago

But now I have a new problem. As I create a new post I always have an empty comment attached to it and if I want to destroy it I get "no route matches". Could you please help me out with this as well. Thanks! Regards, Picki

picki Over a year ago

Hi, the Comment.new leads to "undefined method `new' for nil:NilClass" as for comments I only have "_comment.html.erb _form.html.erb".

polarblau Over a year ago

It's pretty hard to guess without the controller and view code. Could you show some more?

picki Over a year ago

Added the controller codes to my initial post. Do you need to see more? Thanks again for your help. regards, picki

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