續集–多對多關聯

Question

我定義了兩個模型：

db / models / User.js

const Sequelize = require('sequelize');

module.exports = (sequelize, DataTypes) => {
  class User extends Sequelize.Model {}

  const config = {
    sequelize,
    modelName: 'user',
    underscored: true,
    paranoid: true,
  });

  User.init({
    first_name: {
      type: DataTypes.STRING,
    },
    last_name: {
      type: DataTypes.STRING,
    },
  }, config);

  return User;
};

db / models / Group.js

const Sequelize = require('sequelize');

module.exports = (sequelize, DataTypes) => {
  class Group extends Sequelize.Model {}

  const config = {
    sequelize,
    modelName: 'group',
    underscored: true,
    paranoid: true,
  });

  Group.init({
    name: {
      type: DataTypes.STRING,
      allowNull: false,
    },
  }, config);

  return Group;
};

我想在那時之間建立多對多關聯（這樣一個組可以有許多用戶，並且一個用戶可以屬於多個組。這是我的db/index.js ：

db / index.js

const Sequelize = require('sequelize');
const Logger = require('../config/logger');
const { DB } = require('../config/vars');
const UserModel = require('./models/User');
const GroupModel = require('./models/Group');

const sequelize = new Sequelize(
  DB.name,
  DB.username,
  DB.password,
  {
    host: DB.host,
    dialect: 'postgres',
  },
);

const Models = {
  User: UserModel(sequelize, Sequelize),
  Group: GroupModel(sequelize, Sequelize),
};

const setup = async () => {
  // Associations
  Models.User.belongsToMany(Models.Group, {
    through: 'UserGroups',
    as: { singular: 'group', plural: 'groups' },
  });
  Models.Group.belongsToMany(Models.User, {
    through: 'UserGroups',
    as: { singuler: 'user', plural: 'users' },
  });
  await sequelize.sync({ force: true });
};

module.exports = {
  ...Models,
  setup,
  Seeders,
  Sequelize,
  sequelize,
};

當我執行User.findAll() ，對象中沒有返回groups屬性。 我應該如何在這里正確建立多對多關系？

Answer 1

User.findAll()會默認返回與之相關的模型，您需要使用include例如：

User.findAll({
    include : {
        model : Groups 
    }
})

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