Rails 7注册表单提交报错：ActiveRecord::NotNullViolation

问题场景 #

在Ubuntu 22系统的Rails 7应用中测试注册表单，提交POST请求时触发ActiveRecord::NotNullViolation错误，提示inscriptions表的club_id列违反非空约束，提交的club_id值为null。

错误日志 #

Started POST "/inscriptions" for 127.0.0.1 at 2023-06-18 15:44:51 +0200
Processing by InscriptionsController#create as TURBO_STREAM
  Parameters: {"authenticity_token"=>"[FILTERED]", "inscription"=>{"vorname"=>"Jade", "name"=>"Doe", "age"=>"13", "adress"=>"3 Marguerite Youcenar", "email"=>"jade_doe@gmail.com", "phone"=>"0768324654", "gender"=>"feminin"}, "commit"=>"Envoyer"}
  TRANSACTION (0.5ms)  BEGIN
  ↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
  Inscription Create (11.6ms)  INSERT INTO "inscriptions" ("vorname", "name", "age", "adress", "email", "phone", "gender", "created_at", "updated_at", "club_id") VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) RETURNING "id"  [["vorname", "Jade"], ["name", "Doe"], ["age", "13"], ["adress", "3 Marguerite Youcenar"], ["email", "jade_doe@gmail.com"], ["phone", "0768324654"], ["gender", "feminin"], ["created_at", "2023-06-18 13:44:51.944100"], ["updated_at", "2023-06-18 13:44:51.944100"], ["club_id", nil]]
  ↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
  TRANSACTION (0.9ms)  ROLLBACK
  ↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
Completed 500 Internal Server Error in 30ms (ActiveRecord: 13.0ms | Allocations: 5257)


  
ActiveRecord::NotNullViolation (PG::NotNullViolation: ERREUR:  une valeur NULL viole la contrainte NOT NULL de la colonne « club_id » dans la relation « inscriptions »
DETAIL:  La ligne en échec contient (15, Jade, Doe, 13, 3 Marguerite Youcenar, jade_doe@gmail.com, 0768324654, feminin, 2023-06-18 13:44:51.9441, 2023-06-18 13:44:51.9441, null).
):

相关代码 #

InscriptionsController

class InscriptionsController < ApplicationController
  before_action :set_inscription, only: %i[ show edit update destroy ]

  # GET /inscriptions or /inscriptions.json
  def index
    @inscriptions = Inscription.all
  end

  # GET /inscriptions/1 or /inscriptions/1.json
  def show
  end

  # GET /inscriptions/new
  def new
    @inscription = Inscription.new
  end

  # GET /inscriptions/1/edit
  def edit
  end

  # POST /inscriptions or /inscriptions.json
  def create
    @inscription = Inscription.new(inscription_params)

    respond_to do |format|
      if @inscription.save
        format.html { redirect_to inscription_url(@inscription), notice: "Inscription was successfully created." }
        format.json { render :show, status: :created, location: @inscription }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @inscription.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /inscriptions/1 or /inscriptions/1.json
  def update
    respond_to do |format|
      if @inscription.update(inscription_params)
        format.html { redirect_to inscription_url(@inscription), notice: "Inscription was successfully updated." }
        format.json { render :show, status: :ok, location: @inscription }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @inscription.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /inscriptions/1 or /inscriptions/1.json
  def destroy
    @inscription.destroy

    respond_to do |format|
      format.html { redirect_to inscriptions_url, notice: "Inscription was successfully destroyed." }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_inscription
      @inscription = Inscription.find(params[:id])
    end

    # Only allow a list of trusted parameters through.
    def inscription_params
      params.require(:inscription).permit(:club_name, :age, :vorname, :name, :adress, :email, :phone, :gender)
    end
end

Inscription模型

class Inscription < ApplicationRecord
  belongs_to :club, :optional => true

  #validates :club_name, presence: true
  validates :name, presence: true
  validates :age, presence: true, numericality: { only_integer: true, greater_than: 0 }
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }
  validates :phone, presence: true , format: { with: /\A\d{10}\z/ }
end

Club模型

class Club < ApplicationRecord
  belongs_to :ClubAdulte
  belongs_to :ClubTeevo
  belongs_to :ClubJeuneLecteur
end

错误原因分析 #

1. 数据库约束优先级高于模型设置：虽然Inscription模型中设置了belongs_to :club, optional: true，但数据库层面inscriptions表的club_id列被设置为非空（NOT NULL），导致提交null值时触发数据库约束错误。
2. 表单未提交club_id参数：从请求参数可以看到，提交的inscription数据中没有club_id字段，且控制器的inscription_params也未允许该参数通过。
3. Club模型关联命名错误：Club模型中的belongs_to关联使用了大写开头的模型名（如:ClubAdulte），违反Rails约定（应为单数小写，如:club_adulte），会导致关联查找失败。

解决方案 #

根据业务需求选择以下方案：

方案1：要求每个Inscription必须关联Club #

如果业务规则要求注册必须选择俱乐部，按以下步骤修改：

1. 在表单中添加club_id字段：比如添加下拉选择框或隐藏字段，确保提交时包含club_id参数。
2. 更新控制器的强参数：在inscription_params中添加:club_id到允许列表：

   def inscription_params
     params.require(:inscription).permit(:club_id, :club_name, :age, :vorname, :name, :adress, :email, :phone, :gender)
   end
   

3. 修正模型关联验证：移除optional: true，添加俱乐部存在验证：

   class Inscription < ApplicationRecord
     belongs_to :club
     validates :club, presence: true
     # 其他验证规则...
   end
   

方案2：允许Inscription不关联Club #

如果注册可以不选择俱乐部，需要修改数据库约束：

1. 生成迁移文件：

   rails generate migration ChangeClubIdToNullableInInscriptions
   

2. 编辑迁移文件，修改club_id允许为空：

   class ChangeClubIdToNullableInInscriptions < ActiveRecord::Migration[7.0]
     def change
       change_column_null :inscriptions, :club_id, true
     end
   end
   

3. 运行迁移：

   rails db:migrate
   

4. 保留模型的optional设置：确保Inscription模型中的belongs_to :club, optional: true保留，维持模型层面的允许空规则。

额外修正：Club模型关联命名 #

修正Club模型的关联命名为Rails约定的单数小写形式：

class Club < ApplicationRecord
  belongs_to :club_adulte
  belongs_to :club_teevo
  belongs_to :club_jeune_lecteur
end

内容的提问来源于stack exchange，提问作者Piercel Moussa