Defining Entities

When defining entities with MikroORM (Version 5), the following should be considered: The property decorator requires explicit assignment of the type to the property and may not work correctly when working with type inference or assigning union types to a property. In these cases, the metadata may not be set correctly, which can lead to exceptions, for example, when using the em.assign() or em.aggregate() functions.

Therefore, the following is not sufficient:

@Entity()
export class ExampleEntity {
    @Property()
    termsAccepted = false;

    @Property()
    createdAt = new Date();
}

The following works:

@Entity()
export class ExampleEntity {
    @Property()
    termsAccepted: boolean = false;

    @Property()
    createdAt: Date = new Date();
}

The better way is to provide the type through the decorator:

@Entity()
export class ExampleEntity {
    @Property({ type: 'boolean' })
    termsAccepted = false;

    @Property({ type: Date })
    createdAt = new Date();
}

Errors can also occur when specifying multiple types (union types):

@Entity()
export class ExampleEntity {
    @Poperty({ nullable: true })
    dueDate: Date | null;
}

To set the metadata correctly, do the following:

@Entity()
export class ExampleEntity {
    @Property({ type: Date, nullable: true })
    dueDate: Date | null;
}

If type inference is not used, specifying the type through the property decorator is not necessary:

@Entity()
export class ExampleEntity {
    @Property()
    name: string;
}

For more information refer to the MikroORM documentation.