Sequelize中EagerLoadingError问题（模型关联）排查与解决

问题场景 #

尝试使用findAll结合include进行预加载时，触发关联不存在的错误，以下是相关代码及错误信息：

业务代码 #

async function getAllTasks() {
  try {
    const tasks = await Task.findAll({
      include: User,
    });
    return tasks;
  } catch (error) {
    throw error;
  }
}

关联定义文件（associations.js） #

function applyExtraSetup(sequelize) {
const User = require("./User");
const Task= require("./Task");

 Task.belongsTo(User, { foreignKey: "userId" });
 User.hasMany(Task, { foreignKey: "userId" });

}
module.exports = { applyExtraSetup };

Task模型文件 #

const { Sequelize, DataTypes } = require("sequelize");
const sequelize = require("../../config/database"); 
const User = require("./User");

const Task = sequelize.define(
  "Task",
  {
    id: {
      type: DataTypes.INTEGER,
      autoIncrement: true,
      primaryKey: true,
    },
    name: {
      type: DataTypes.STRING,
      allowNull: false,
    },
    userId: {
      type: DataTypes.INTEGER,
      allowNull: false,
      references: {
        model: User,
        key: "id",
      },
    },
  },
  {
    tableName: "Tasks",
  }
);

module.exports = Task;

初始化文件（init.js） #

const { Sequelize } = require("sequelize");
const sequelize = require("./config/database");
const { applyExtraSetup } = require("./app/models/associations");

const User = require("./app/models/User");
const Task = require("./app/models/Task");

applyExtraSetup(sequelize);

sequelize.sync({ alter: true }).catch((err) => {
  console.log(err);
});

错误信息 #

EagerLoadingError [SequelizeEagerLoadingError]: User is not associated to Task!

解决方案 #

通过给模型添加静态associate方法，并在初始化阶段统一执行关联定义，解决了关联未正确绑定的问题：

修改Task模型 #

class Task extends Model {
  static associate(models) {
    Task.belongsTo(models.User, { foreignKey: "userId" });
  }
}

Task.init(
  {
    id: {
      type: DataTypes.INTEGER,
      autoIncrement: true,
      primaryKey: true,
    },
    name: {
      type: DataTypes.STRING,
      allowNull: false,
    },
    userId: {
      type: DataTypes.INTEGER,
      allowNull: false,
      references: {
        model: User,
        key: "id",
      },
    },
  },
  {
    sequelize,
    tableName: "Tasks",
  }
);

module.exports = Task;

修改init.js #

const { Sequelize } = require("sequelize");
const sequelize = require("./config/database");
const models = require("./app/models");

// 批量执行所有模型的关联定义
Object.values(models).forEach((model) => {
  if (model.associate) {
    model.associate(models);
  }
});

sequelize.sync({ alter: true }).catch((err) => {
  console.log(err);
});

说明 #

该方案通过模型内置的associate方法管理关联关系，在初始化时批量执行关联绑定，解决了原方式中关联未生效的问题。目前已能正常运行，仍有优化空间。

内容的提问来源于stack exchange，提问作者Fino