Relations Overview

Hysteria ORM supports rich relation types between models:

• belongsTo
• hasOne
• hasMany
• manyToMany

Relations are retrieved using batch loading, so one query is made for each relation only if withRelation is called. Be carefull, too many relation retrieve could slow down you overall query

Example Models

class User extends Model {
  @hasMany(() => Post, 'userId')
  declare posts: Post[];

  @manyToMany(() => Address, () => UserAddress, {
    leftForeignKey: 'userId',
    rightForeignKey: 'addressId',
  })
  declare addresses: Address[];
}

class Post extends Model {
  @belongsTo(() => User, 'userId')
  declare user: User;
}

class Address extends Model {
  @manyToMany(() => User, () => UserAddress, {
    leftForeignKey: 'addressId',
    rightForeignKey: 'userId',
  })
  declare users: User[];
}

Querying Relations

Eager Loading

const users = await User.query().withRelation('posts').many();

Nested Relations

const users = await User.query().withRelation('posts', Post, (qb) =>
  qb.withRelation('user')
).many();

Filtering on Relations

const users = await User.query().withRelation('posts', Post, (qb) =>
  qb.where('title', 'Hello World')
).many();

Best Practices

• Use withRelation for batch relation loading.
• Use callbacks for nested and filtered relations.
• Always define foreign keys explicitly for clarity.

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Next: Advanced SQL Features