爲什麼Rails爲我的模型中存在的屬性提供了'No Method Error'？ - Rails的3

Question

這是錯誤我得到：

NoMethodError in Devise::RegistrationsController#create 

undefined method `trial_duration' for nil:NilClass 
app/models/user.rb:120:in `set_trial_end' 

這是有關部分我User.rb

before_create :set_trial_end 

def set_trial_end 
    plan = self.plan 
    end_of_trial = Date.today + self.plan.trial_duration.days 
    self.trial_end_date = end_of_trial.to_date 
end 

什麼奇怪的是，當我看着我的數據庫，對用戶是分配計劃，並期待在trial_duration屬性，我得到的答覆：

ruby-1.9.2-p0 > tu 
=> #<User id: 29, email: "test50@abc.com", encrypted_password: "$2a$10$TKKQmBYem.vDq.mwDutv2u92Vick0X0jAIUQT6A9.FM....", password_salt: "$2a$10$TKKQmBYem.vDq.mwDutv2u", reset_password_token: nil, remember_token: nil, remember_created_at: nil, sign_in_count: 1, current_sign_in_at: "2011-06-18 23:03:12", last_sign_in_at: "2011-06-18 23:03:12", current_sign_in_ip: "127.0.0.1", last_sign_in_ip: "127.0.0.1", username: "test50", first_name: "Test", last_name: "Fifty", created_at: "2011-06-18 23:02:48", updated_at: "2011-06-18 23:03:12", invitation_token: nil, invitation_sent_at: nil, plan_id: 2, current_state: nil, confirmation_token: nil, confirmed_at: "2011-06-18 23:03:12", confirmation_sent_at: "2011-06-18 23:02:47", space_used: 0, failed_attempts: 0, unlock_token: nil, locked_at: nil, trial_end_date: "2011-07-02", active_subscription: nil, customer_id: nil> 
ruby-1.9.2-p0 > tu.plan 
=> #<Plan id: 2, name: "Boutique", storage: 100.0, num_of_projects: 99999, num_of_clients: 10, cached_slug: "boutique", created_at: "2011-01-31 09:46:57", updated_at: "2011-08-11 08:22:48", amount: 19, trial_duration: 14, trial_duration_unit: "days", currency: "USD", billing_cycle: 28, billing_cycle_unit: "days"> 
ruby-1.9.2-p0 > tu.plan.trial_duration 
=> 14 
ruby-1.9.2-p0 > tu.plan.trial_duration.days 
=> 14 days 

所以不知道爲什麼Rails的是給我的錯誤。

任何想法？

編輯1：

在我看來，我有這樣的：

<% if params[:promo] %> 
    <%= text_field_tag "xcode", nil, :placeholder => "Coupon Code" %><br /> 
<%= hidden_field_tag(:plan_id, "1") %> 
<% end %> 

與後，從我的日誌，你可以看到參數plan_id設置爲1

Started POST "/users" for 127.0.0.1 at 2011-08-24 03:11:07 -0500 
    Processing by Devise::RegistrationsController#create as HTML 
    Parameters: {"utf8"=>"✓", "authenticity_token"=>"Jp2GHxnuVOVnI/sfr1CB4EQ9URCTJynv/2Ek4AiU8Lg=", "user"=>{"username"=>"test.user", "first_name"=>"Testing", "last_name"=>"User", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]", "email"=>"testuser@abc.com"}, "xcode"=>"testcouponcode", "plan_id"=>"1", "commit"=>"Register"} 
nil 

但我仍然收到下一頁上的錯誤Plan can't be blank。

我已經添加了after_validation而不是after_create，所以我不再是NoMethodError。但問題沒有解決。

Answer 1

您使用的是before_create掛鉤這是假設該self.plan設置：

before_create :set_trial_end 

def set_trial_end 
    #... 
    end_of_trial = Date.today + self.plan.trial_duration.days 

而你的錯誤說：

undefined method `trial_duration' for nil:NilClass 

所以self.plan是你set_trial_end通話期間nil。

也許你想要一個after_create掛鉤，這樣你就可以使用一些實例數據。即使如此，你會想檢查self.plan.nil?（以防萬一），並使用驗證，以確保你得到一個：

class User < ActiveRecord::Base 
    validates_presence_of :plan_id 
    #... 

或者，也許一個after_validation鉤將更好地爲您服務。