EventsController 中的 NoMethodError#create undefined method ‘build’ for nil:NilClass?

Question

我对为什么会收到此错误感到有点困惑，因为（我认为）这表明我的 current_customer returns 为零。我不知道如何解决这个问题，这是我的 current_customer 方法、会话控制器还是我的 events_controller...

的问题

事件模型：

class Event < ActiveRecord::Base
  belongs_to :calendar

end

事件控制器：

class EventsController < ApplicationController

  def new
    @event = Event.new
    @calendar = current_customer.calendar #WHY IS IT NOT ERRORING HERE TOO?

  end


  def create

    **@calendar = current_customer.calendar #IT IS CALLING ERROR HERE**
    @event = @calendar.build.event(event_params)
    if @event.save
      redirect_to '/main'
    else
      redirect_to '/compose'
    end
  end


  private
  def event_params
    params.require(:event).permit(:calendar_id, :name, :starts_at, :ends_at) 
  end

客户模型：

class Customer < ActiveRecord::Base
  belongs_to :business
  has_one :calendar

  has_secure_password

  attr_accessor :remember_token

  #remembers a user in the database for  use in persistent sessions
  def remember
    self.remember_token = Customer.new_token
    update_attribute(:remember_digest, Customer.digest(remember_token))
  end

  def Customer.digest(string)
    cost = ActiveModel::SecurePassword.min_cost ? BCrypt::Engine::MIN_COST :
        BCrypt::Engine.cost
    BCrypt::Password.create(string, cost: cost)
  end

  def forget
    update_attribute(:remember_digest, nil)
  end

  def Customer.new_token
    SecureRandom.urlsafe_base64
  end

  #returns true if the given token matches the digest
  def authenticated?(remember_token)
    BCrypt::Password.new(remember_digest).is_password?(remember_token)
  end


end

客户控制员：

class CustomersController < ApplicationController

  def new

    @customer = Customer.new
    @businesses = Business.all
    @calendar = Calendar.new

  end

  def create

    @customer = Customer.create(customer_params)

    @calendar = @customer.build_calendar
    @customer.save!
    session[:customer_id] = @customer.id

    redirect_to '/'
  rescue ActiveRecord::RecordInvalid => ex
    render action: 'new', alert: ex.message
  end

  private
  def customer_params
    params.require(:customer).permit(:first_name, :last_name, :business_no, :email, :password, :business_id)
  end

end

会话控制器：

class SessionsController < ApplicationController

  def new

  end

  def create
    @customer = Customer.find_by_email(params[:session][:email])
    if @customer && @customer.authenticate(params[:session][:password])
      session[:customer_id] = @customer.id #log in
      @customer.remember
      cookies.permanent.signed[:customer_id] = @customer.id
      cookies.permanent[:remember_token] = @customer.remember_token
      redirect_to '/main'
    else
      #need to add flash error: invalid password/email combination
      redirect_to '/login'
    end
  end

  def destroy
    @current_customer.forget
    cookies.delete(:customer_id)
    cookies.delete(:remember_token)
    session.delete(:customer_id)
    @current_customer = nil
    redirect_to '/'
  end
end

Current_customer 方法 application.controller:

helper_method :current_customer

  def current_customer
    if (customer_id = session[:customer_id])
      @current_customer ||= Customer.find_by(id: customer_id)
    elsif (customer_id = cookies.signed[:customer_id])
      customer = Customer.find_by(id: customer_id)
      if customer && customer.authenticated?(cookies[:remember_token])
        session[:customer_id] = customer.id #log in
        @current_customer = customer

      end
    end
  end

日历模型：

class Calendar < ActiveRecord::Base
  belongs_to :customer
  has_many :events

end

calendars_controller:

class CalendarsController < ApplicationController

  def new
    @calendar = Calendar.new(calendar_params)

  end

  def create
    @calendar = Calendar.new(calendar_params)
  end

private
  def calendar_params
    params.require(:customer_id)
  end

end

我是 Ruby/Rails 的新手，所以非常感谢任何解释和答案，请帮忙！谢谢

Answer 1

@calendar = current_customer.calendar
@event = @calendar.build.event(event_params)

根据错误消息，@calendar 是 nil，因此当您在下一行调用 @calendar.build.event(event_params) 时，它调用：nil.build 因此您得到错误。

出于某种原因，对于该请求，您的 current_customer 的 calendar 是 nil。找出并确保 current_customer 在数据库中存在 calendar，然后它应该可以工作。

此外，您需要更改：

@event = @calendar.build.event(event_params)

收件人：

@event = @calendar.events.build(event_params)

Answer 2

在事件控制器中，@calendar 似乎是 nil。

首先检查 current_customer 返回您预期的客户。

然后检查 current_customer 是否创建了供您参考的日历。

EventsController 中的 NoMethodError#create undefined method ‘build’ for nil:NilClass?

NoMethodError in EventsController#create undefined method `build' for nil:NilClass?

ruby

ruby-on-rails

nomethoderror

ruby-on-rails-3

ruby-on-rails-4