Rails 3中未定义的方法“ model_name”

Question

While rendering xml for an object, I am getting the error

NoMethodError (undefined method `model_name' for OrderResponse:Class):

OrderResponse.rb

class OrderResponse
   include ActiveModel::Serialization

   attr_accessor :payload
end

In controller

def create
  @order_response = OrderResponse.new
  @order_response.payload = 12345

  respond_to do |format|
    format.xml { render :xml => @order_response }
  end
end

I found other questions with similar titles while searching, according to that i modified 'respond_to' with 'respond_with' which inturns throws an error

undefinedMethod 'model_name' in OrderResponse

How to solve this?

Answer 1

I found an answer to this somewhere on stackoverflow and wish I could credit the source... This is my interpretation of it.

In Rails 3, if you have a resource listed in your routes which has a model .rb file but no active record table behind it, then you'll see this kind of error. This appeared for me as a form_for trying to reference a :controller and :action in this model. Perhaps it is related to Rails attempting to process associations for the model or something similar. Either way, this is new for me since I upgraded an application from Rails 2.3.8.

For me, the appears as:

undefined method `model_name' for SomeModel:Class

To fix it, at the top of the affected class add:

extend ActiveModel::Naming
include ActiveModel::Conversion
def persisted?
  false
end

This has worked for me on two models like this.

Answer 2

您可以尝试使用该名称定义一个类方法，该方法返回该类的名称：

def self.model_name; 'OrderResponse'; end

Answer 3

尝试包括ActiveSupport::CoreExtensions::Module ，其中模型名称被定义的ActiveSupport :: CoreExtensions ::模块