How to use sequelize to fetch object data? - mysql

Question

I am trying to implement Sequelize as an ORM in NodeJs and I am using it for Mysql,
I have 3 tables in the sample -
1. Role
2. User (Has a role)
3. Code (IsCreated by a user)
I'm unable to query the tables/models properly,
As I should be receiving an model representation of a table, which is referred as a foreign key.
Following is my DB structure -
1. Role table -
2. User table -
3. Code table -
Following are the table creation queries -
1. Role -
CREATE TABLE role (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(100) NOT NULL,
PRIMARY KEY (id)
);
2. User -
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL,
`email` varchar(100) NOT NULL,
`role` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `role` (`role`),
CONSTRAINT `user_ibfk_1` FOREIGN KEY (`role`) REFERENCES `role` (`id`)
);
3. Code -
CREATE TABLE `code` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL,
`createdBy` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `createdBy` (`createdBy`),
CONSTRAINT `code_ibfk_1` FOREIGN KEY (`createdBy`) REFERENCES `user` (`id`)
);
Following is my app.js file -
const db = require('./db');
const Code = require('./code');
const User = require('./user');
const Role = require('./role');
const async = require('async');
async.waterfall([
function(callback) {
db
.authenticate()
.then(() => {
console.log('Connection has been established successfully.');
callback(null,"ok");
})
.catch(err => {
return callback(err,null);
});
},
function(resp,callback) {
Code.findAll({include: [{ model: User}]})
.then(code => {
console.log("All users:", JSON.stringify(code, null, 4));
callback(null,"ok");
})
.catch(err => {
callback(err,null);
});
// Code.findOne({
// where: {
// id: 1
// }
// })
// .then(code => {
// console.log("All users:", JSON.stringify(code, null, 4));
// })
// .catch(err => console.log("Error => \n",err));
},
],
function(err, resp) {
if (err) {
console.log(err);
} else {
console.log(resp);
}
});
Following is my db.js file -
const Sequelize = require('sequelize');
module.exports = new Sequelize('junit', 'root', 'root', {
host: 'localhost',
/* one of 'mysql' | 'mariadb' | 'postgres' | 'mssql' */
dialect: 'mysql',
//operatorsAliases: false,
pool: {
max: 5,
min: 0,
acquire: 30000,
idle: 10000
}
});
Following is my role.js file -
const Sequelize = require('sequelize');
const db = require('./db');
const User = require('./user');
const Role = db.define('role', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull:false,
autoIncrement: true
},
name: {
type: Sequelize.STRING
}
}, {
tableName: 'role',
freezeTableName: true,
timestamps: false
});
associate : (models) => {
Role.hasMany(models.User,{
foreignKey: 'role'
});
};
module.exports = Role;
Following is my user.js file -
const Sequelize = require('sequelize');
const db = require('./db');
const Code = require('./code');
const Role = require('./role');
const User = db.define('user', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull:false,
autoIncrement: true
},
name: {
type: Sequelize.STRING
},
email: {
type: Sequelize.STRING
},
role: {
type: Sequelize.INTEGER,
references: {
// This is a reference to another model
model: Role,
// This is the column name of the referenced model
key: 'id'
}
}
}, {
tableName: 'user',
freezeTableName: true,
timestamps: false
});
associate : (models) => {
User.hasMany(models.Code,{
foreignKey: 'createdBy'
});
User.belongsTo(models.Role,{
foreignKey: 'role'
});
};
module.exports = User;
Following is my code.js file -
const Sequelize = require('sequelize');
const db = require('./db');
const User = require('./user');
//one-to-many
const Code = db.define('code', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull:false,
autoIncrement: true
},
name: {
type: Sequelize.STRING
},
// createdBy: {
// type: Sequelize.INTEGER
// },
createdBy: {
type: Sequelize.INTEGER,
references: {
// This is a reference to another model
model: User,
// This is the column name of the referenced model
key: 'id'
}
}
}, {
tableName: 'code',
freezeTableName: true,
timestamps: false
});
associate : (models) => {
Code.belongsTo(models.User,{
foreignKey: 'createdBy'
});
};
module.exports = Code;
When I run the app.js file I can't see the model reference of User,
But I get the usual Integer value, Can someone please help on how to properly use the Model here?
Error trace -

Answer 1

Looks like you're trying to fetch Code when connection wasn't established yet.
Try this:
const db = require('./db');
const Code = require('./code');
const User = require('./user');
const Role = require('./role');
function run() {
return db
.authenticate()
.then(() => Code.findOne({ // you can try execute whenever query you want here
where: {
id: 1
}})
.then(code => {
console.log("All users:", JSON.stringify(code, null, 4));
})
.catch(err => console.log("Error => \n",err)))
.catch(err => {
console.error('Unable to connect to the database:', err);
});
}
run();