需要解决的错误:

ActiveRecord::StatementInvalid: Mysql2::Error: Cannot delete or update a parent row: a foreign key constraint fails (slap_chat_development.chatrooms, CONSTRAINT fk_rails_496733c195 FOREIGN KEY (group_id) REFERENCES groups (id)): DELETE FROM groups WHERE groups.id = 1

问题是:

• 谁能指导我应该从哪里修复这个错误。

据我所知，groups 和 chatrooms 表之间的关系仍然存在问题。

更多详情:

架构.rb

ActiveRecord::Schema.define(version: 20160606100750) do

  create_table "chatrooms", force: :cascade do |t|
    t.integer  "group_id",   limit: 4
    t.string   "name",       limit: 255
    t.datetime "created_at",             null: false
    t.datetime "updated_at",             null: false
  end

  add_index "chatrooms", ["group_id"], name: "index_chatrooms_on_group_id", using: :btree

  create_table "chatrooms_users", force: :cascade do |t|
    t.integer  "chatroom_id", limit: 4
    t.integer  "user_id",     limit: 4
    t.datetime "created_at",            null: false
    t.datetime "updated_at",            null: false
  end

  add_index "chatrooms_users", ["chatroom_id"], name: "index_chatrooms_users_on_chatroom_id", using: :btree
  add_index "chatrooms_users", ["user_id"], name: "index_chatrooms_users_on_user_id", using: :btree

  create_table "groups", force: :cascade do |t|
    t.string   "name",       limit: 255
    t.integer  "user_id",    limit: 4
    t.datetime "created_at",             null: false
    t.datetime "updated_at",             null: false
  end

  add_index "groups", ["user_id"], name: "index_groups_on_user_id", using: :btree

  create_table "groups_users", force: :cascade do |t|
    t.integer  "group_id",   limit: 4
    t.integer  "user_id",    limit: 4
    t.datetime "created_at",           null: false
    t.datetime "updated_at",           null: false
  end

  add_index "groups_users", ["group_id"], name: "index_groups_users_on_group_id", using: :btree
  add_index "groups_users", ["user_id"], name: "index_groups_users_on_user_id", using: :btree

  create_table "posts", force: :cascade do |t|
    t.integer  "user_id",    limit: 4
    t.datetime "created_at",             null: false
    t.datetime "updated_at",             null: false
    t.string   "content",    limit: 255
  end

  add_index "posts", ["user_id"], name: "index_posts_on_user_id", using: :btree

  create_table "users", force: :cascade do |t|
    t.string   "email",                  limit: 255, default: "", null: false
    t.string   "encrypted_password",     limit: 255, default: "", null: false
    t.string   "reset_password_token",   limit: 255
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          limit: 4,   default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip",     limit: 255
    t.string   "last_sign_in_ip",        limit: 255
    t.datetime "created_at",                                      null: false
    t.datetime "updated_at",                                      null: false
    t.string   "first_name",             limit: 255
    t.string   "nick_name",              limit: 255
    t.string   "last_name",              limit: 255
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree
  add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree

  add_foreign_key "chatrooms", "groups"
  add_foreign_key "chatrooms_users", "chatrooms"
  add_foreign_key "chatrooms_users", "users"
  add_foreign_key "groups", "users"
  add_foreign_key "groups_users", "groups"
  add_foreign_key "groups_users", "users"
  add_foreign_key "posts", "users"
end

组模型:

class Group < ActiveRecord::Base
  has_many :chatrooms
  belongs_to :group_admin, class_name: "User", foreign_key: :user_id
  has_and_belongs_to_many :members, class_name: "User", association_foreign_key: :user_id

  validates :user_id, presence: true
  validates :name, presence: true, length: { minimum: 3 }

  before_create { self.name = self.name.capitalize }
  after_create :assign_creator
  around_destroy :destroy_all_associates

  def general_room
    self.chatrooms.where("name = ?", "general").take
  end

  def except_general_room
    self.chatrooms.select { |room| room != self.general_room }
  end

  def assign_creator
    member = self.group_admin
    self.members << member
    self.general_room.members << member
  end

  def destroy_all_associates
    rooms = self.chatrooms
    yield
    rooms.each do |room|
        room.destroy
    end
  end
end

聊天室模型:

class Chatroom < ActiveRecord::Base
  belongs_to :group
  has_and_belongs_to_many :members, class_name: "User", association_foreign_key: :user_id

  validates :name, presence: true, length: { minimum: 3 }

  before_save { self.name = self.name.downcase }
  around_create :ensure_group_presence
  around_destroy :destroy_all_associates

  def feed
    ids = Array.new
    self.members.each do |member|
        ids += member.post_ids
    end
    Post.where("id IN (?)", ids)
  end

  def ensure_group_presence
    yield
    self.group_id.present?
  end

  def destroy_all_associates
    feed = self.feed
    yield
    feed.destroy_all
  end
end

最佳答案

您可以尝试在您的小组模型中使用它。

class Group < ActiveRecord::Base
  has_many :chatrooms , dependent: :destroy
end

现在当你执行 Group.last.destroy 时，它应该删除之前依赖的关联聊天室，并且不会留下任何挂起的数据

关于mysql - ActiveRecord::StatementInvalid: Mysql2::Error: 无法删除或更新父行 - Rails 4.2.6，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37664061/