Question

我试图通过一个已经在mySql中创建的新表来关联2个表。然后，我可以从API获取所需的数据。与新表链接的2个表是用户和国家。用户可以访问许多国家。一个国家可以被许多用户访问。

这是我的模型User.js：

const Sequelize = require('sequelize')
const db = require('../database/db.js')
const Country = require('./Country')

const User = db.sequelize.define('user', 
{
    id: {
        type: Sequelize.INTEGER,
        primaryKey: true,
        autoIncrement: true
    },
    name: {
        type: Sequelize.STRING
    },
    firstName: {
        type: Sequelize.STRING
    },
    password: {
        type: Sequelize.STRING
    },
    admin: {
        type: Sequelize.TINYINT
    }
},
{
    freezeTableName: true,
    timestamps: false,       
});
User.associate = () => {
    User.belongsToMany(Country, {
        through: 'Country_user',
        as: 'country',
        foreignKey: 'id_user'
    });
};

module.exports = User

这是我的模型Country.js：

const Sequelize = require('sequelize')
const db = require('../database/db.js')
const User = require('./User')

const Country = db.sequelize.define('country', 
    {
        id: {
            type: Sequelize.INTEGER,
            primaryKey: true,
            autoIncrement: true
        },
        code: {
            type: Sequelize.INTEGER        
        },
        alpha2: {
            type: Sequelize.STRING
        },
        alpha3: {
            type: Sequelize.STRING
        },
        name_en: {
            type: Sequelize.STRING
        },
        name_fr: {
            type: Sequelize.STRING
        }
    },
    {
        freezeTableName: true,
        timestamps: false
    });
    Country.associate = () => {
      Country.belongsToMany(User, {
        through: 'Country_user',
        as: 'user',
        foreignKey: 'id_country'
      });
    };

module.exports = Country;

这是我的模型Country_user.js：

const Sequelize = require('sequelize')
const db = require('../database/db.js')

const Country_user = db.sequelize.define('country_user', {
    id_user: {
        type: Sequelize.INTEGER,
        allowNull: false,
        references: {
            model: 'User',
            key: 'id'
        }
    },
    id_country: {
        type: Sequelize.INTEGER,
        allowNull: false,
        references: {
            model: 'Country',
            key: 'id'
        }
      }
    });

module.exports = Country_user

最后，这是我的查询，以获取我需要的数据：

var express = require('express')
var router = express.Router()
const User = require('../../models/User')
const Country = require('../../models/Country')

    router.get('/user', function(req, res, next){
        User.findAll({
            include: [{
                model: Country,
                as: 'country',
                attributes: ['id', 'name_fr'],
                through: { attributes: [] }
            }]
        })
            .then(user => {
                res.json(user)
            })
            .catch(err => {
                res.send('error: ' + err)
            })
    })

    module.exports = router

我希望ORM不会在数据库中创建新字段。我已经创建了它们。我只想将这些外键链接到ORM中的右表，以便可以轻松获取数据。

当我尝试使用路由/ user时，我是从POSTMAN那里获得的：

错误：SequelizeEagerLoadingError：国家与用户未关联！

编辑：db.js文件的构建方式如下：

const Sequelize = require('sequelize')
const db = {}
const sequelize = new Sequelize('travel_memories', 'root', '', {
    host: 'localhost',
    dialect: 'mysql',
    port: 3306
})

sequelize
  .authenticate()
  .then(() => {
    console.log('Connection has been established successfully.');
  })
  .catch(err => {
    console.error('Unable to connect to the database:', err);
  });

db.sequelize = sequelize
db.Sequelize = Sequelize

module.exports = db

Answer 1

您是否通过这样的方式运行模型？

Object.keys(models).forEach((modelName) => {
  if ('associate' in models[modelName]) {
    // console.log(models[modelName]);
    models[modelName].associate(models);
  }
});

要真正建立关联？？仅在“国家和用户”中添加belongsToMany关联逻辑是不够的

我的models目录中有一个索引文件，它会执行类似的操作，我将为您进行一些修改，您需要将“ path_to”语句替换为您的正确路径。...< / p>

import { Sequelize } from 'sequelize';
import sequelize from '../../helpers/db';

const models = {
  Country: sequelize.import('./path_to_country'),
  User: sequelize.import('./path_to_user'),
  CountryUserJoin: sequelize.import('./path_to_join')      
};

Object.keys(models).forEach((modelName) => {
  if ('associate' in models[modelName]) {
    // console.log(models[modelName]);
    models[modelName].associate(models);
  }
});

models.sequelize = sequelize;
models.Sequelize = Sequelize;

export default models;

Answer 2

const Sequelize = require('sequelize')
const db = {}
const sequelize = new Sequelize('travel_memories', 'root', '', {
    host: 'localhost',
    dialect: 'mysql',
    port: 3306
})

sequelize
  .authenticate()
  .then(() => {
    console.log('Connection has been established successfully.');
  })
  .catch(err => {
    console.error('Unable to connect to the database:', err);
  });

const models = {
  Country: sequelize.import('../../models/Country'),
  User: sequelize.import('../../models/User'),
  CountryUserJoin: sequelize.import('../../models/Country_user')      
};

Object.keys(models).forEach((modelName) => {
  if ('associate' in models[modelName]) {
// console.log(models[modelName]);
models[modelName].associate(models);
  }
});

db.sequelize = sequelize
db.Sequelize = Sequelize

module.exports = db

Answer 3

这是我在自己的js文件中编写我的方式的方法：

module.exports = function (sequelize, DataTypes) {
  const Country = sequelize.define('loc_countries', {
    id: {
      type: DataTypes.BIGINT,
      allowNull: false,
      primaryKey: true,
      autoIncrement: true,
    },
    name: {
      type: DataTypes.STRING,
      allowNull: true,
    },
    abbr2: {
      type: DataTypes.STRING,
      allowNull: true,
    },
    abbr3: {
      type: DataTypes.STRING,
      allowNull: true,
    },
  }, {
    freezeTableName: true,
    timestamps: false,
    tableName: 'loc_countries',
  });

  Country.associate = function (models) {
    models.Country.hasMany(models.ProvinceState, { as: 'ProvStates', foreignKey: 'loc_countries_id' });
  };

  return Country;
};

BelongToMany与Sequelize表未关联

3 个答案: