Rails Associations出现'nil'(Rails Associations appearing 'nil')

 我是Rails和Web Dev的新手，真的很难过。 我有两个模型user和property 。 除非您是用户（已登录），否则无法创建属性。 我在user模型has_many properties和property模型中的belongs_to user中遇到了关联问题。 创建属性时，当我检查控制台时，它具有正确的user_id 。 
 
 问题：当我在控制台中检查用户时，我收到消息property_id: nil 。 有人可以解释我需要什么代码才能为user填充property_id吗？ （我认为它可能与在属性之前创建的用户有关，但我认为关联会自动处理这个） 
 
 我正在使用devise ，因为这是一个因素，我添加了:property_id到允许的参数方法。 
 
 相关代码如下： 
 
 楷模： 
 
class Property < ActiveRecord::Base

belongs_to :user, dependent: :destroy
validates :user_id, presence: true 
mount_uploader :picture, PictureUploader
end
 
 2） 
 
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

has_many :properties

end
 
 控制器： 
 
class PropertiesController < ApplicationController

before_action :authenticate_user!, except: [:index]
before_action :set_user, only: [:show, :edit, :update]


def index
    @properties = Property.all
end

def new 
    @property = current_user.properties.new
end

def create
    @property = current_user.properties.new(property_params)
    respond_to do |format|
      if @property.save
        format.html { redirect_to @property, notice: "Property was successfully created." }
        format.json { render :show, location: @property }
      else
        format.html { render :new }
        format.json 
      end
    end
end

def update      
    respond_to do |format|
      if @property.update(property_params)
        format.html { redirect_to @property, notice: "You've successfully updated your property listing!" }
        format.json { render :show, status: :ok, location: @property }
      else
        format.html { render :edit }
        format.json { render json: @property.errors, status: :unprocessable_entity }
      end
    end
end

end
 
 2） 
 
class UsersController < ApplicationController

before_action :authenticate_user!
load_and_authorize_resource

def index
    @users = User.all
end

end
 
 应用控制器： 
 
class ApplicationController < ActionController::Base
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception
before_action :configure_permitted_parameters, if: :devise_controller?


protected

def configure_permitted_parameters
devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(:name, :email,       :password, :password_confirmation, :property_id) }
end

I'm new to Rails and Web Dev and really stumped. I have two models user andproperty. You cannot create a property unless you are a user (logged in). I'm having problems with associations as I have in the user model has_many properties and belongs_to user in property model. When a property is created, when I check the console, it has the correct user_id. 
 
Problem: When I check the user in the console, I get message property_id: nil. Can someone explain what code I need in order for the property_id to populate for the user? (I figure it probably has something to do with the user being created before the property but I thought the associations would automatically take care of this) 
 
I'm using devise in case that is a factor and I added :property_id to the permitted parameters method. 
 
Relevant code is below:
 
Models:
 
class Property < ActiveRecord::Base

belongs_to :user, dependent: :destroy
validates :user_id, presence: true 
mount_uploader :picture, PictureUploader
end
 
2)
 
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

has_many :properties

end
 
Controllers:
 
class PropertiesController < ApplicationController

before_action :authenticate_user!, except: [:index]
before_action :set_user, only: [:show, :edit, :update]


def index
    @properties = Property.all
end

def new 
    @property = current_user.properties.new
end

def create
    @property = current_user.properties.new(property_params)
    respond_to do |format|
      if @property.save
        format.html { redirect_to @property, notice: "Property was successfully created." }
        format.json { render :show, location: @property }
      else
        format.html { render :new }
        format.json 
      end
    end
end

def update      
    respond_to do |format|
      if @property.update(property_params)
        format.html { redirect_to @property, notice: "You've successfully updated your property listing!" }
        format.json { render :show, status: :ok, location: @property }
      else
        format.html { render :edit }
        format.json { render json: @property.errors, status: :unprocessable_entity }
      end
    end
end

end
 
2)
 
class UsersController < ApplicationController

before_action :authenticate_user!
load_and_authorize_resource

def index
    @users = User.all
end

end
 
Application Controller:
 
class ApplicationController < ActionController::Base
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception
before_action :configure_permitted_parameters, if: :devise_controller?


protected

def configure_permitted_parameters
devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(:name, :email,       :password, :password_confirmation, :property_id) }
end

原文：https://stackoverflow.com/questions/35375533