sequelize-typescript

Decorators and some other features for sequelize (v6).

• Installation
• Model Definition
  • @Table API
  • @Column API
• Usage
  • Configuration
  • globs
  • Model-path resolving
• Model association
  • One-to-many
  • Many-to-many
  • One-to-one
  • @ForeignKey, @BelongsTo, @HasMany, @HasOne, @BelongsToMany API
  • Generated getter and setter
  • Multiple relations of same models
• Indexes
  • @Index API
  • createIndexDecorator() API
• Repository mode
  • How to enable repository mode?
  • How to use repository mode?
  • How to use associations with repository mode?
  • Limitations of repository mode
• Model validation
• Scopes
• Hooks
• Why () => Model?
• Recommendations and limitations

Installation

• this assumes usage of sequelize@6
• sequelize-typescript requires sequelize
• additional typings as documented here and reflect-metadata

npm install --save-dev @types/node @types/validator
npm install sequelize reflect-metadata sequelize-typescript

Your tsconfig.json needs the following flags:

"target": "es6", // or a more recent ecmascript version
"experimentalDecorators": true,
"emitDecoratorMetadata": true

Sequelize Options

• SequelizeConfig renamed to SequelizeOptions
• modelPaths property renamed to models

Scopes Options

The @Scopes and @DefaultScope decorators now take lambda's as options

@DefaultScope(() => ({...}))
@Scopes(() => ({...}))

instead of deprecated way:

@DefaultScope({...})
@Scopes({...}))

Model definition

import { Table, Column, Model, HasMany } from 'sequelize-typescript';

@Table
class Person extends Model {
  @Column
  name: string;

  @Column
  birthday: Date;

  @HasMany(() => Hobby)
  hobbies: Hobby[];
}

Less strict

import { Table, Model } from 'sequelize-typescript';

@Table
class Person extends Model {}

More strict

import { Optional } from 'sequelize';
import { Table, Model } from 'sequelize-typescript';

interface PersonAttributes {
  id: number;
  name: string;
}

interface PersonCreationAttributes extends Optional<PersonAttributes, 'id'> {}

@Table
class Person extends Model<PersonAttributes, PersonCreationAttributes> {}

The model needs to extend the Model class and has to be annotated with the @Table decorator. All properties that should appear as a column in the database require the @Column annotation.

See more advanced example here.

@Table

The @Table annotation can be used without passing any parameters. To specify some more define options, use an object literal (all define options from sequelize are valid):

@Table({
  timestamps: true,
  ...
})
class Person extends Model {}

Table API

Primary key

A primary key (id) will be inherited from base class Model. This primary key is by default an INTEGER and has autoIncrement=true (This behaviour is a native sequelize thing). The id can easily be overridden by marking another attribute as primary key. So either set @Column({primaryKey: true}) or use @PrimaryKey together with @Column.

@CreatedAt, @UpdatedAt, @DeletedAt

Annotations to define custom and type safe createdAt, updatedAt and deletedAt attributes:

  @CreatedAt
  creationDate: Date;

  @UpdatedAt
  updatedOn: Date;

  @DeletedAt
  deletionDate: Date;

@Column

The @Column annotation can be used without passing any parameters. But therefore it is necessary that the js type can be inferred automatically (see Type inference for details).

  @Column
  name: string;

If the type cannot or should not be inferred, use:

import {DataType} from 'sequelize-typescript';

  @Column(DataType.TEXT)
  name: string;

Or for a more detailed column description, use an object literal (all attribute options from sequelize are valid):

  @Column({
    type: DataType.FLOAT,
    comment: 'Some value',
    ...
  })
  value: number;

Column API

Shortcuts

If you're in love with decorators: sequelize-typescript provides some more of them. The following decorators can be used together with the @Column annotation to make some attribute options easier available:

Type inference

The following types can be automatically inferred from javascript type. Others have to be defined explicitly.

Accessors

Get/set accessors do work as well

@Table
class Person extends Model {
  @Column
  get name(): string {
    return 'My name is ' + this.getDataValue('name');
  }

  set name(value: string) {
    this.setDataValue('name', value);
  }
}

Usage

Except for minor variations sequelize-typescript will work like pure sequelize. (See sequelize docs)

Configuration

To make the defined models available, you have to configure a Sequelize instance from sequelize-typescript(!).

import { Sequelize } from 'sequelize-typescript';

const sequelize = new Sequelize({
  database: 'some_db',
  dialect: 'sqlite',
  username: 'root',
  password: '',
  storage: ':memory:',
  models: [__dirname + '/models'], // or [Player, Team],
});

Before you can use your models you have to tell sequelize where they can be found. So either set models in the sequelize config or add the required models later on by calling sequelize.addModels([Person]) or sequelize.addModels([__dirname + '/models']):

sequelize.addModels([Person]);
sequelize.addModels(['path/to/models']);

globs

import {Sequelize} from 'sequelize-typescript';

const sequelize =  new Sequelize({
        ...
        models: [__dirname + '/**/*.model.ts']
});
// or
sequelize.addModels([__dirname + '/**/*.model.ts']);

Model-path resolving

A model is matched to a file by its filename. E.g.

// File User.ts matches the following exported model.
export class User extends Model {}

This is done by comparison of the filename against all exported members. The matching can be customized by specifying the modelMatch function in the configuration object.

For example, if your models are named user.model.ts, and your class is called User, you can match these two by using the following function:

import {Sequelize} from 'sequelize-typescript';

const sequelize =  new Sequelize({
  models: [__dirname + '/models/**/*.model.ts']
  modelMatch: (filename, member) => {
    return filename.substring(0, filename.indexOf('.model')) === member.toLowerCase();
  },
});

For each file that matches the *.model.ts pattern, the modelMatch function will be called with its exported members. E.g. for the following file

//user.model.ts
import {Table, Column, Model} from 'sequelize-typescript';

export const UserN = 'Not a model';
export const NUser = 'Not a model';

@Table
export class User extends Model {

  @Column
  nickname: string;
}

The modelMatch function will be called three times with the following arguments.

user.model UserN -> false
user.model NUser -> false
user.model User  -> true (User will be added as model)

Another way to match model to file is to make your model the default export.

export default class User extends Model {}

⚠️ When using paths to add models, keep in mind that they will be loaded during runtime. This means that the path may differ from development time to execution time. For instance, using .ts extension within paths will only work together with ts-node.

Build and create

Instantiation and inserts can be achieved in the good old sequelize way

const person = Person.build({ name: 'bob', age: 99 });
person.save();

Person.create({ name: 'bob', age: 99 });

but sequelize-typescript also makes it possible to create instances with new:

const person = new Person({ name: 'bob', age: 99 });
person.save();

Find and update

Finding and updating entries does also work like using native sequelize. So see sequelize docs for more details.

Person.findOne().then((person) => {
  person.age = 100;
  return person.save();
});

Person.update(
  {
    name: 'bobby',
  },
  { where: { id: 1 } }
).then(() => {});

Model association

Relations can be described directly in the model by the @HasMany, @HasOne, @BelongsTo, @BelongsToMany and @ForeignKey annotations.

One-to-many

@Table
class Player extends Model {
  @Column
  name: string;

  @Column
  num: number;

  @ForeignKey(() => Team)
  @Column
  teamId: number;

  @BelongsTo(() => Team)
  team: Team;
}

@Table
class Team extends Model {
  @Column
  name: string;

  @HasMany(() => Player)
  players: Player[];
}

That's all, sequelize-typescript does everything else for you. So when retrieving a team by find

Team.findOne({ include: [Player] }).then((team) => {
  team.players.forEach((player) => console.log(`Player ${player.name}`));
});

the players will also be resolved (when passing include: Player to the find options)

Many-to-many

@Table
class Book extends Model {
  @BelongsToMany(() => Author, () => BookAuthor)
  authors: Author[];
}

@Table
class Author extends Model {
  @BelongsToMany(() => Book, () => BookAuthor)
  books: Book[];
}

@Table
class BookAuthor extends Model {
  @ForeignKey(() => Book)
  @Column
  bookId: number;

  @ForeignKey(() => Author)
  @Column
  authorId: number;
}

Type safe through-table instance access

To access the through-table instance (instanceOf BookAuthor in the upper example) type safely, the type need to be set up manually. For Author model it can be achieved like so:

  @BelongsToMany(() => Book, () => BookAuthor)
  books: Array<Book & {BookAuthor: BookAuthor}>;

One-to-one

For one-to-one use @HasOne(...)(foreign key for the relation exists on the other model) and @BelongsTo(...) (foreign key for the relation exists on this model)

@ForeignKey, @BelongsTo, @HasMany, @HasOne, @BelongsToMany API