OCaml约束中的隐式类型变量的范围(Scope of implicit type variables in OCaml constraints)

 感谢Michal的意见，我重新安排了我的控制器，以便通过关联公司创建用户，而不是相反。 相应的公司控制器如下所示： 
 
 companies_controller.rb 
 
# GET company/new
def new
    @company = Company.new
    @company.users.build
end

# POST company/
def create
    @company = Company.new(params[:company])

    respond_to do |format|
      if @company.save
        format.html { redirect_to root_path, notice: 'Welcome! Your account has been created successfully. A confirmation link has been sent to your email address.' }
        format.json { render json:  root_path, status: :created, location: @company }
      else
        format.html { render action: "new" }
        format.json { render json: @company.errors, status: :unprocessable_entity }
      end
    end
end
 
 GET请求的表单嵌套了Devise User模型字段，如下所示： 
 
 new.html.erb 
 
<h2>Create an account</h2>
<%= simple_form_for( @company, :html => {:class => 'form-horizontal' }) do |f| %>
<%= render 'shared/error_messages', :object => @company %>
    <%= f.input     :name, 
                    :label =>'Company name',
                    :placeholder => "Example Company Inc.",
                    :autofocus => true %>
    <%= f.simple_fields_for :users do |builder| %>
        <%= builder.input   :email, 
                            :placeholder => "example@email.com" %>
        <%= builder.input :password %>
        <%= builder.input :password_confirmation %>
    <% end %>
    <%= f.button    :submit, 'Create account',
                    :class => 'btn'%>
<% end %>
<%= link_to "Sign in", new_session_path(:user) %>
 
 现在，如果验证失败，则所有实例属性值将保留在其各自的表单字段中。 

Thanks to Michal's input, I rearranged my controllers so that a user will be created through an associated company and not the other way round. The respective company controller looks like this:
 
companies_controller.rb
 
# GET company/new
def new
    @company = Company.new
    @company.users.build
end

# POST company/
def create
    @company = Company.new(params[:company])

    respond_to do |format|
      if @company.save
        format.html { redirect_to root_path, notice: 'Welcome! Your account has been created successfully. A confirmation link has been sent to your email address.' }
        format.json { render json:  root_path, status: :created, location: @company }
      else
        format.html { render action: "new" }
        format.json { render json: @company.errors, status: :unprocessable_entity }
      end
    end
end
 
The form the GET request nests the Devise User model fields as follows:
 
new.html.erb
 
<h2>Create an account</h2>
<%= simple_form_for( @company, :html => {:class => 'form-horizontal' }) do |f| %>
<%= render 'shared/error_messages', :object => @company %>
    <%= f.input     :name, 
                    :label =>'Company name',
                    :placeholder => "Example Company Inc.",
                    :autofocus => true %>
    <%= f.simple_fields_for :users do |builder| %>
        <%= builder.input   :email, 
                            :placeholder => "example@email.com" %>
        <%= builder.input :password %>
        <%= builder.input :password_confirmation %>
    <% end %>
    <%= f.button    :submit, 'Create account',
                    :class => 'btn'%>
<% end %>
<%= link_to "Sign in", new_session_path(:user) %>
 
Now, if the validation fails, all instance attribute values remain in their respective form field.