Routing error when using nested resources

Question

I have a Post and Comment models. Comment belongs to a Post, and it is nested under Post in routes. Comments are posted from Posts#show. My routes look like this:

  resources :posts do
    resources :comments, only: [:create, :edit, :update, :destroy]
  end

If a user submits a comment that fails validation, the URL will look like this:

app.com/posts/:id/comments

If, for any reason, the user decides to hit enter in the address bar, there will be a routing error:

Routing Error
No route matches [GET] "/posts/21/comments"
Try running rake routes for more information on available routes.

This strikes me as some what odd. I understand why the error is happening, but it doesn't seem like it's a good idea for usability. Is there a way to prevent this from happening?

This becomes a bigger issue when doing friendly redirects. When a friendly redirect happens, Rails will redirect to that same URL using a GET request, again causing a routing error.

Lucca Mordente · Accepted Answer · 2012-09-13 19:48:33Z

1

I think that the best way to avoid it is to create a route for this case and redirect to wherever make sense for your application. Something like the following:

match "/posts/:id/comments" => redirect {|params| "/posts/#{params[:id]}" }

Instead of that routing error, the user would be redirected to the post page.

answered Sep 13, 2012 at 19:48

Lucca Mordente

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2 Comments

Mohamad Over a year ago

Interesting, what about in the case of a post request, or a user submission, is there a way to preserve the params and continue with post submission?

Lucca Mordente Over a year ago

You can store the params in a cookie. Also you'd have to control whether you have to retrieve the stored data or not to try the submission again.

Marlin Pierce · Accepted Answer · 2012-09-13 20:15:21Z

1

If your routes are

resources :posts do
  resources :comments, only: [:create, :edit, :update, :destroy]
end

then the URL for edit would be

app.com/posts/:post_id/comments/:id/edit

where :id is the comment. If validation fails, you should be redirecting back to this URL.

def update
  @post = Post.find(params[:post_id])
  @comment = @post.comments.find(params[:id])

  if @comment.update_attributes(params[:comment])
    redirect_to(edit_post_path(@post))
  else
    redirect_to(edit_post_comment_path(@post, @comment), :notice => "update failed")
  end
end

Better, since you are already at the correct edit URL,

...
  else
    flash[:error] = "Error - could not update comment"
    render :action => "edit"
  end

answered Sep 13, 2012 at 20:15

Marlin Pierce

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2 Comments

Mohamad Over a year ago

Just to be clear, your example update method, is do you mean this is in the posts controller or the comments controller?

Marlin Pierce Over a year ago

I should have included the class name. It's the comments controller.

Pawel · Accepted Answer · 2012-09-13 19:53:23Z

0

Not the best but the other solution may be to add comments through nested attributes of post.

answered Sep 13, 2012 at 19:53

Pawel

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