Rails 4、通过join table在has_many中指定自定义外键？

Question

我想在我的 rails 4 应用程序中通过关联在 has_many 的连接 table 中指定一个自定义外键。请看下面，我到目前为止有什么...

当我在 rails 控制台中执行 user.team_memberships.create 时，我收到此错误：

ActiveRecord::UnknownAttributeError: unknown attribute 'user_id' for TeamMembership.

users.rb

class User < ActiveRecord::Base
    has_many :team_memberships
    has_many :teams, through: :team_memberships

teams.rb

class Team < ActiveRecord::Base
    has_many :team_memberships
    has_many :members, through: :team_memberships

team_membership.rb

    class TeamMembership < ActiveRecord::Base
      belongs_to :member, class_name: 'User', foreign_key: 'member_id'
      belongs_to :team

schema.rb

create_table "team_memberships", force: :cascade do |t|
    t.integer  "member_id"
    t.integer  "team_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

  add_index "team_memberships", ["member_id"], name: "index_team_memberships_on_member_id", using: :btree
  add_index "team_memberships", ["team_id"], name: "index_team_memberships_on_team_id", using: :btree

  create_table "teams", force: :cascade do |t|
    t.string   "name"
    t.integer  "team_snap_id"
    t.datetime "created_at",   null: false
    t.datetime "updated_at",   null: false
  end

  create_table "users", force: :cascade do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.inet     "current_sign_in_ip"
    t.inet     "last_sign_in_ip"
    t.datetime "created_at",                          null: false
    t.datetime "updated_at",                          null: false
    t.string   "name"
    t.integer  "teamsnap_uid"
    t.string   "teamsnap_access_token"
  end

Answer 1

您需要将 foreign_key: 'member_id' 添加到 User 的 has_many 声明中。您还可以删除 TeamMembership 中 belongs_to 上的 foreign_key 选项 - Rails 将自动推断出这一点。

user.rb

class User < ActiveRecord::Base
  has_many :team_memberships, foreign_key: 'member_id'
  has_many :teams, through: :team_memberships

team_membership.rb

class TeamMembership < ActiveRecord::Base
  belongs_to :member, class_name: 'User'
  belongs_to :team

Answer 2

您需要在两个模型中指定外键

class User < ActiveRecord::Base
  has_many :team_memberships, foreign_key: 'member_id'
  has_many :teams, through: :team_memberships
end

和

class TeamMembership < ActiveRecord::Base
  belongs_to :member, class_name: 'User', foreign_key: 'member_id'
  belongs_to :team
end

如果你不在用户模型中添加外键那么你将无法为用户创建团队成员同样如果你不在团队成员中指定外键那么你将无法获得团队的用户会员资格。

Rails 4、通过join table在has_many中指定自定义外键？

Rails 4, specify custom foreign key in has_many through join table?

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has-many-through