qb.getResultAndCount() fails on execution, if Entity field type uses TS allias

[DenisLutsky]

Describe the bug

...
const qb = this.orm.em.createQueryBuilder(UserEntity, 'user');
const [items, count] = await qb.select('*').getResultAndCount();
...

Code like this example will fail with the exception posted below if the field of entity using named type alias instead of notation with a pipe and the recond in DB table has value that is not NULL

type Nullable<T> = T | null;

@Property({ columnType: 'varchar', length: 50, nullable: true })
public firstName!: string | null; // works fine

@Property({ columnType: 'varchar', length: 50, nullable: true })
public firstName!: Nullable<string>; // fails and fails only with QB, em.find working fine

ValidationError: Trying to set UserEntity.firstName of type 'object' to 'John' of type 'string'
    at Function.fromWrongPropertyType (C:\projects\_\node_modules\@mikro-orm\core\errors.js:23:16)
    at EntityValidator.validateProperty (C:\projects\_\node_modules\@mikro-orm\core\entity\EntityValidator.js:73:48)
    at C:\projects\_\node_modules\@mikro-orm\core\entity\EntityValidator.js:25:35
    at Array.forEach (<anonymous>)
    at EntityValidator.validate (C:\projects\_\node_modules\@mikro-orm\core\entity\EntityValidator.js:14:20)
    at SqlEntityManager.merge (C:\projects\_\node_modules\@mikro-orm\core\EntityManager.js:1147:22)
    at SqlEntityManager.map (C:\projects\_\node_modules\@mikro-orm\core\EntityManager.js:1123:21)
    at QueryBuilder.getResultList (C:\projects\_\node_modules\@mikro-orm\knex\query\QueryBuilder.js:664:36)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Promise.all (index 0) - [32/14]

The problem appeared after updating mikro-orm to version 6.x, on previous (4, 5) there were no problems with that

Reproduction

1. Setup NestJS application
2. Create TS type alias type Nullable<T> = T | null;
3. Create entity class
   eg.

@Entity({ tableName: 'users' })
export class UserEntity extends BaseEntity {
  @PrimaryKey()
  public userId!: number;

  @Property({ columnType: 'varchar', length: 50, nullable: true })
  public firstName!: Nullable<string>;

  @Property({ columnType: 'varchar', length: 50, nullable: true })
  public lastName!: Nullable<string>;

  @Property({ columnType: 'varchar', length: 320, unique: true })
  public email!: string;

  @Property({ columnType: 'text' })
  public password!: string;

  @Property({ columnType: 'bool', default: false })
  public isDeleted!: boolean;

  @Property({ columnType: 'timestamp', defaultRaw: 'current_timestamp' })
  public createdAt!: Date;

  @Property({ columnType: 'timestamp', defaultRaw: 'current_timestamp', onUpdate: () => new Date() })
  public updatedAt!: Date;

  public [OptionalProps]?: 'userId' | 'isDeleted' | 'createdAt' | 'updatedAt';
}

3. Inject MikroORM instanc with PG driver using public constructor(private readonly orm: MikroORM<PostgreSqlDriver>) {}
4. Build query builder request
   e.g.

...
const qb = this.orm.em.createQueryBuilder(UserEntity, 'user');
const [items, count] = await qb.select('*').getResultAndCount();
...

What driver are you using?

@mikro-orm/postgresql

MikroORM version

6.1.0

Node.js version

node v20.10.0, npm 10.2.3

Operating system

Windows 11

Validations

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• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Slack.
• The provided reproduction is a minimal reproducible example of the bug.

[B4nan]

Using ts-morph I guess? That's the important part here that you skipped from the report.

Setup NestJS application

If this is your first step to set up a minimal repro, you don't understand what a minimal repro means :] You don't need web server to reproduce anything.

[B4nan]

What TS version are you using? I am not able to reproduce this with 5.3. On the other hand, I know quite well what's happening and I can fix that, it's just not reproducible on my end.

[DenisLutsky]

Thank you for fix.

I'm sorry for bad repro steps.

No, I don't use ts-morph
TS version "typescript": "^5.3.3"

[B4nan]

Hmm, then it needs to be caused by SWC, their reflect-metadata support is pretty broken, so many differences...

Anyway, the fix I did should cover this too, the property type validation is now limited only to a set of known types, and those don't include object.

You can also get around such problems by specifying the type explicitly:

@Property({ type: 'string', length: 50, nullable: true }) // strings are by default mapped to varchar
public firstName!: Nullable<string>;

And one more note - your entity definition is a bit wrong, since you use columnType and length next to each other - the length has no effect there, you need to include it in the columnType as that is always used as is, without any postprocessing.

@Property({ columnType: 'varchar(50)', nullable: true })
public firstName!: Nullable<string>;