Question

I am trying to get my posts tagged with a certain tag to render. My code in the view is

Views/posts/sports.html.erb

 <% my_posts = post.find_by_tag("sports") %>
 <%= my_posts.each do |post| %>
    <%= post.title %><br />
    <%= post.body %><br />
 <% end %>

my controller for this looks like

 def sports
     @posts = Post.paginate(:page => params[:page], :per_page => 10)
     @post = Post.find(params[:id])
     @title = "Newest"


     respond_to do |format|
       format.html
       format.json { render :json => @users }
     end
 end

I know I have to define the @post variable but I’m not sure what to define it as.

UPDATE

The problem I’m having is a “Couldn’t find Post without an ID” error

Second UPDATE

   def find_by_tag name 
     Tag.find_by_name(name).posts 
   end

Answer 1

Part of the problem, based on what is shown here, is that you are defining instance variables with Post object(s) in the controller, and then not using them for anything in the view. To retrieve a collection of all the posts tagged “sports,” you’d do the following in the controller:

@sports_posts = Post.find_by_tag("sports")

and in the view:

<% @sports_posts.each do |post|
  etc...

To add pagination, you can just chain that method to the original:

@sports_posts = Post.find_by_tag("sports").paginate(:page => params[:page],
                                                    :per_page => 10)

This is different from your snippet, where you define a @posts variable that returns a collection of 10 Post objects, and @post which simply finds a post object based on the id passed by the submitting form params. My guess is that this controller action is not getting created by a form submission, so no params are passed, and therefore params[:id] is nil, hence the error messages you see. In any event, unless you need either of those items in your view (and there’s nothing here to suggest they’re being used for anything), there’s no reason to create them.

What you do need is a collection of posts tagged “sports”, which is what the call above accomplishes. It looks like you are trying to do that with post.find_by_tag("sports") in the view. The problem is that you are calling the find_by_tag method on post, which doesn’t exist. Post exists – that’s the Post class, and probably what you mean to be calling. Just changing post to Post would probably get you where you want, but content retrieval and presentation are better separated if you create your objects in the controller and then use the view to simply render their attribute data (per the example above).