View with data from different tables connected with foreign key

For my project, I try to understand how to let data view on a single view from different tables. I tried to implement the example of the Ruby on Rails Tutorial (http://ruby.railstutorial.org/chapters/user-microposts#sec:a_micropost_model). In this example I'm able to see the microposts of a user on the user's page. So what was I doing?

1. I generated a table for user with rails generate scaffold user name:string + rake db:migrate
2. I generated a table for microposts with rails generate scaffold micropost content:string user_id:integer
3. I added into db/migrate/..._create_microposts.rb def self.up (...) add_index :microposts, :user_id add_index :microposts, :created_at end
4. I added the foreign/primary-key- relations into microposts- model belongs_to :user & users- model has_many :microposts
5. rake db:migrate
6. I changed the users-Show-html-View: app/views/users/show.html.erb <% unless @user.microposts.empty? %> <%= render @microposts %> < %end% >
7. For the command "render", I paginated the micropostpage app/views/microposts/_micropost.html.erb with content <% = micropost.content %> posted <% = time_ago_in_words(micropost.created_at)%> ago

I've already filled some content and rails console says that rails already knows the link between both tables. Anyways, if I open the show action, I get some error:

NoMethodError in Users#show

Showing c:/src/script/testtest2/app/views/users/show.html.erb where line #13 raised:

undefined method `model_name' for NilClass:Class

Extracted source (around line #13):

10:  </p>
11: 
12: <% unless @user.microposts.empty? %>
13:     <%= render @microposts %>
14: <% end %>
15:  
16: <%= link_to 'Edit', edit_user_path(@user) %> |

Rails.root: c:/src/script/testtest2
Application Trace | Framework Trace | Full Trace

app/views/users/show.html.erb:13:in `_app_views_us开发者_JAVA百科ers_show_html_erb___161211003_22878180__702430867'
app/controllers/users_controller.rb:18:in `show'

Request

Parameters:

{"id"=>"1"}

It seems like rails doesn't like "render", so what did I do wrong? Unluckily I skipped some chapters of the tutorial, because I just simply want to know how to list microposts on the User-show page. Do I need to define more? In the tutorial, there's much more code, but this code also contains lots of definition for the css-Stylesheet, so I'm confused which code is really necessary for simply solving my problem.

Replace <%= render @microposts %> in show.html.erb with <%= render @user.microposts %>