RubyOnRails - Creating new objects with relations - ruby-on-rails

Question

i have 2 models, User and Technician
class User < ActiveRecord::Base
has_one :technician
end
class Technician < ActiveRecord::Base
belongs_to :user
validates :user, presence: true
end
When creating a new Technician and trying to associate with an existing User it gives the error: User cannot be blank
the view of Technician.new (form) is:
<%= form_for(#technician) do |f| %>
<% if #technician.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#technician.errors.count, "error") %> prohibited this technician from being saved:</h2>
<ul>
<% #technician.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :codigo %><br>
<%= f.number_field :codigo %><br><br>
<%= f.label :user_id %><br>
<%= f.select :user_id, options_for_select(User.all.map{|u|[u.nome, u.id]}) %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
What am I doing wrong if, selecting an user from the select it won't associate it to the attribute user_id?
Thanks

Answer 1

Try using with collect like this
<%= f.select :user_id, User.all.collect {|u|[u.nome, u.id]}) %>
OR
If you are using Rails 4,you can use pluck
<%= f.select :user_id, User.pluck(:nome, :id))
For more details see this API
If that doesn't work,change your validation in Technician model like this
class Technician < ActiveRecord::Base
belongs_to :user
validates :user_id, presence: true
end
Update
As you are using Rails4,you should be adding user_id to the permitted parameters like this
def your_params
params.require(:technician).permit(:user_id,:codigo)
end