Lazy loading of related entities

When an entity is loaded, its many to one relation fields are also automatically loaded, using a cache mechanism to prevent the reload of an already loaded entity. To disable that, set the lazy option to true.

let's use the example in entity relations

@Entity("tasks", {
  allowApiCrud: true
})
export class Task extends IdEntity {
  @Fields.string()
  title = ""
  @Fields.boolean()
  completed = false
  @Field(() => Category, {
    lazy: true
  })
  category?: Category
}

Working with Lazy

• To manually load a related entity, use its FieldRef's load method.

  await task.$.category!.load()

• If the field was not loaded, and you'll access it - it'll return undefined and will issue a request to load the related entity. once that entity is loaded, the field will return its value.
• To check if a field has value, you can use the valueIsNull method of its FieldRef

  await task.$.category!.valueIsNull()

• You can override the default lazy definitions by setting the load option of the repository's find method.
  • To load none of the related entities use:

    await taskRepo.find({
      load: () => []
    })

  • To specify which fields to load:

    await taskRepo.find({
      load: task => [task.category!]
    })