Rails Mysql2::Error: 字段 'email' 没有默认值：

Question

我正在使用 rails 4.2.10 在尝试使用 Sorcery Gem 注册用户时出现错误。我正在从 rails 3.2 升级应用程序

ActiveRecord::StatementInvalid in UsersController#createActiveRecord

Mysql2::Error: 字段 'email' 没有默认值：INSERT INTO users (created_at, updated_at) 价值观 ('2018-03-14 21:16:53', '2018-03-14 21:16:53') 提取的源代码（第 48 行附近）：

 @user = User.new(user_params)
respond_to do |format|
 ---line 48-----> if @user.save**
    format.html { render action: "thanks", notice: 'User was successfully created.' }
    format.json { render json: @user, status: :created, location: @user }
  else

userscontroller.rb

class UsersController < ApplicationController

skip_before_action :require_login, only: [:index, :new, :create, :activate]
  # GET /users
  # GET /users.json
  def index
    @users = User.all

     respond_to do |format|
     format.html # index.html.erb
     format.json { render json: @users }
    end
  end

  # GET /users/1
  # GET /users/1.json
  def show
    @user = User.find(params[:id])

     respond_to do |format|
     format.html # show.html.erb
      format.json { render json: @user }
    end
  end

  # GET /users/new
  # GET /users/new.json
  def new
    @user = User.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @user }
    end
  end

  # GET /users/1/edit
  def edit
   @user = User.find(params[:id])
  end

  # POST /users
  # POST /users.json
   def create
    @user = User.new(params[:user])

    respond_to do |format|
      if @user.save
        format.html { render action: "thanks", notice: 'User was successfully created.' }
        format.json { render json: @user, status: :created, location: @user }
      else
        format.html { render action: "new" }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /users/1
  # PUT /users/1.json
  def update
   @user = User.find(params[:id])

    respond_to do |format|
      if @user.update_attributes(params[:user])
        format.html { redirect_to @user, notice: 'User was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
    end

  # DELETE /users/1
  # DELETE /users/1.json
 def destroy
    @user = User.find(params[:id])
    @user.destroy

    respond_to do |format|
      format.html { redirect_to users_url }
      format.json { head :no_content }
    end
  end
  def user_params
      params.require(:user).permit(:email, :password, :password_confirmation)
  end
  def activate
  if (@user = User.load_from_activation_token(params[:id]))
    @user.activate!
    redirect_to(login_path, :notice => 'User was successfully activated.')
 else
    not_authenticated
  end
end
def thanks 
 respond_to do |format|
      format.html # thanks.html.erb
      format.json { render json: @user }
    end
  end
end

================================================ ========================== 这是正确的迁移吗？

    class SorceryCore < ActiveRecord::Migration
      def change
        create_table :users do |t|
         t.string :email,            :null => false
         t.string :crypted_password, :null => false
         t.string :salt,             :null => false

         t.timestamps
       end

        add_index :users, :email, unique: true
      end  
   end

Answer 1

从给出的错误消息来看，电子邮件字段似乎存在“NOT NULL”约束 并且您需要在插入时有一个包含数据的电子邮件字段。

解决此问题的解决方案：

1. 在 db/migrate 中检查迁移，其中定义了与用户模型对应的电子邮件字段。
2. 删除特定迁移的模型/回滚
3. 从迁移文件中移除 null(key) 约束并再次迁移。
4. 检查 schema.rb 并且电子邮件字段不应有 null: false。