rails：在创建过程中尝试设置STI类型时无法大规模分配这些受保护的属性

Question

I have just started out learning rails and ruby, so please bear with me if this is too dumb.

There are several different AppModule types in my app, which have different behavior but similar data, so I save them using single table inheritance.

However when trying allow the user to explicitly select which type they want in app_modules/new.html.erb I get the warning WARNING: Can't mass-assign these protected attributes: type . Here is the relevant code:

<% form_for(@app_module) do |f| %>
  <%= f.error_messages %>

  <p>
    <%= f.label :type %><br />
    <%= f.select( :type, options_from_collection_for_select(AppModule.subclasses().map{ |c| c.name}, 'to_s', 'to_s')) %>
    </p>

  <%= f.submit 'Create' %>
 <% end %>

I have tried explicity setting attr_accessible :type in the model file but it didn't work

I am using rails 2.3.8 and ruby 1.8.7.

Any help greatly appreciated, thanks...

Answer 1

You shouldn't ever have to set the type attribute manually. Use the subclasses you created instead.

model = params[:app_module].delete(:type).constantize
model = AppModule unless model.is_a?(AppModule)
@app_module = model.new(params[:app_module])

Answer 2

Add this to your base class:

  def attributes_protected_by_default
    super - [self.class.inheritance_column]
  end

I recommend Adam's method unless you are dealing with a mixed list.

Answer 3

我只需要在“ config / application.rb”中的以下行中注释即可解决此问题。

# config.active_record.whitelist_attributes = true