Question

I just finished Hartl’s RoR tutorial and am now trying to mess around with some more stuff.

Specifically: I’m trying to allow the user to create microposts on any page, by rendering the micropost partial in the header.html.erb file (which is rendered on every page).

the partial:

<%= form_for(@micropost) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_area :content, placeholder: "micropost" %>
  </div>
  <%= f.submit "Post", class: "btn btn-large btn-primary" %>
<% end %>

Doing this has resulted in the error on line #1 of the partial: undefined method 'model_name' for NilClass:Class on any page which I have not fixed by adding @micropost = current_user.microposts.build in the controller method that links to said view. For example:

#in controllers/static_pages_controller.rb
def about
  if signed_in?
    @micropost = current_user.microposts.build
  end
end

Would fix this error when I visit the about page

I’ve been trying to figure out a way to do a “blanket fix” that will work on all pages without me having to paste in the declaration everywhere, any ideas?

Answer 1

You don’t need to use the form_for builder here; Rails also provides a form_tag helper for more generic forms:

<%= form_tag create_micropost_path, method: :post do %>
  <%= text_area_tag :micropost_content, placeholder: "micropost" %>
  <%= submit_tag "Post", class: "btn btn-large btn-primary" %>
<% end %>

This way, you don’t need to build the object when loading every page, but microposts#create can still pull data from params[:micropost]. See here for more info.