[ Learnt knowledge ]
I am following a basic tutorial to learn sequelize and its associations.
And this book shows only hasMany and belongsTo examples.
With the short knowledge, I am hitting a wall to create some data schema.
[ What I am trying to ]
The data schema is basically about military branch(or unit) assoications.
Atom unit is a team. And a team has a direct superior unit - a section.
Or, if a team does not have a section as a direct superior unit, then, its direct superior unit will be a squad.
Squad > ( Section ) > Team
I wrote something, but I got this error.
Error: Section.belongsTo called with something that's not a subclass of Sequelize.Model
at Function.<anonymous> (/Users/mac/Desktop/modeling/node_modules/sequelize/lib/associations/mixin.js:93:13)
and Here is my code.
model/index.js
const Sequelize = require('sequelize');
const Team = require("./team");
const Section = require("./section");
const Squad = require("./squad");
// const Platoon = require("./platoon");
// const Company = require("./company");
// const Battalion = require("./battalion");
// const Regiment = require("./regiment");
// const Brigade = require("./brigade");
// const Division = require("./division");
// const Corps = require("./corps");
// const Command = require("./command");
// const Unit = require("./branch");
// const DogTag = require("./dogtag");
// const Name = require("./name");
// const Rank = requrie("./rank");
// const Position = require("./position");
// const Branch = requrie("./branch")
// const Soldier = requrie("./soldier");
const env = process.env.NODE_ENV || 'development';
const config = require('../config/config')[env];
const db = {};
const sequelize = new Sequelize(config.database, config.username, config.password, config);
db.sequelize = sequelize;
db.Team = Team;
db.Section = Section;
Team.init(sequelize);
Section.init(sequelize);
Squad.init(sequelize);
Section.associate(db);
Squad.associate(db);
Team.associate(db);
module.exports = db;model/team.js
const Sequelize = require("sequelize");
module.exports = class Team extends Sequelize.Model{
static init(sequelize) {
return super.init({
name : {
type : Sequelize.STRING(20), //STING == MySQL VARCHAR
allowNull : false, // allowNull == MySQL NOT NULL
unique : true, // unique == UNIQUE
},
created_at : {
type : Sequelize.DATE, // DATE == MySQL DATETIME
allowNull : false,
defaultValue : Sequelize.NOW, // defaultValue == MySQL DEFAULT / Sequelize.NOW == now()
}, // should you want ZEROFILL option, use [INTERGER.UNSIGNED].ZEROFILL
},{
sequelize, //connect with model/index.js
timestamps : false,
underscored : false, // createdAt => craeted_at
modelName : 'Team',
tableName : 'teams',
paranoid : 'false', // if is true, deletedAt column will be craeted.
charset : 'utf8',
collate : 'utf8_general_ci',
});
}
static associate(db) {
db.Team.belongsTo(db.Section, {
foreignKey : "sectionID",
targetKey : 'id'
});
db.Team.belongsTo(db.Squad, {
foreignKey : "squadID",
targetKey : 'id'
});
};
}model/section.js
const Sequelize = require("sequelize");
module.exports = class Section extends Sequelize.Model{
static init(sequelize) {
return super.init({
name : {
type : Sequelize.STRING(20), //STING == MySQL VARCHAR
allowNull : false, // allowNull == MySQL NOT NULL
unique : true, // unique == UNIQUE
},
created_at : {
type : Sequelize.DATE, // DATE == MySQL DATETIME
allowNull : false,
defaultValue : Sequelize.NOW, // defaultValue == MySQL DEFAULT / Sequelize.NOW == now()
}, // should you want ZEROFILL option, use [INTERGER.UNSIGNED].ZEROFILL
},{
sequelize, //connect with model/index.js
timestamps : false,
underscored : false, // createdAt => craeted_at
modelName : 'Section',
tableName : 'sections',
paranoid : 'false', // if is true, deletedAt column will be craeted.
charset : 'utf8',
collate : 'utf8_general_ci',
});
}
static associate(db) {
db.Section.hasMany(db.Team, {
foreignKey : "sectionID",
sourceKey : 'id'
});
db.Section.belongsTo(db.Squad, {
foreignKey : "squadID",
targetKey : 'id'
});
};
}model/squad.js
const Sequelize = require("sequelize");
module.exports = class Squad extends Sequelize.Model{
static init(sequelize) {
return super.init({
name : {
type : Sequelize.STRING(20), //STING == MySQL VARCHAR
allowNull : false, // allowNull == MySQL NOT NULL
unique : true, // unique == UNIQUE
},
created_at : {
type : Sequelize.DATE, // DATE == MySQL DATETIME
allowNull : false,
defaultValue : Sequelize.NOW, // defaultValue == MySQL DEFAULT / Sequelize.NOW == now()
}, // should you want ZEROFILL option, use [INTERGER.UNSIGNED].ZEROFILL
},{
sequelize, //connect with model/index.js
timestamps : false,
underscored : false, // createdAt => craeted_at
modelName : 'Squad',
tableName : 'squads',
paranoid : 'false', // if is true, deletedAt column will be craeted.
charset : 'utf8',
collate : 'utf8_general_ci',
});
}
static associate(db) {
db.Squad.hasMany(db.Section, {
foreignKey : "squadID",
sourceKey : 'id'
});
db.Squad.hasMany(db.Team, {
foreignKey : "squadID",
sourceKey : 'id'
});
};
}[ Questions ]
Although I know only few things, I am pretty sure that each static associate(db){} has no code mistakes.
But I am not sure whether a table can have belongsTo more than two.
And I am very curious if I can use belongsToMany instead of belongsTo.
How can I solve this error?
Please, I need help :(
You missed db.Squad = Squad; line in index.js:
db.Team = Team;
db.Section = Section;
db.Squad = Squad; // add this line
Team.init(sequelize);
Section.init(sequelize);
Squad.init(sequelize);
Section.associate(db);
Squad.associate(db);
Team.associate(db);
That's why at this line
db.Section.belongsTo(db.Squad, {
foreignKey : "squadID",
targetKey : 'id'
});
you passed undefined as db.Squad