EntityFactory.create fails if the entity class constructor uses destructuring assignment.

[rangelfinal]

Describe the bug
When using destructuring assignment on a entity class constructor, meta.constructorParams is set as [undefined] on EntitySchema.setClass, which is reflected as extractConstructorParams returning [undefined] on EntityFactory.createEntity and the following return new Entity(...params); failing with a TypeError.

mikro-orm/packages/core/src/metadata/EntitySchema.ts

Line 190 in 4fd39fc

this._meta.constructorParams = Utils.getParamNames(proto, 'constructor');

mikro-orm/packages/core/src/entity/EntityFactory.ts

Lines 76 to 80 in 4fd39fc

	const params = this.extractConstructorParams<T>(meta, data);
	meta.constructorParams.forEach(prop => delete data[prop]);
	// creates new instance via constructor as this is the new entity
	return new Entity(...params);

That seems to happen when Utils.getParamNames gets to the case 'BindingElement': return p.left.name;, and p.left.name is undefined as the destructuring assignment parameter is unamed.

mikro-orm/packages/core/src/utils/Utils.ts

Lines 243 to 244 in 8018c41

	case 'BindingElement':
	return p.left.name;

A possible fix would be to check if p.left is defined but p.left.name is undefined - then it's probably a destructuring assignment and the property names should be found on p.left.properties.

To Reproduce

import { Entity, PrimaryKey } from '@mikro-orm/core';
import { v4 } from 'uuid';

@Entity()
class User {
   @PrimaryKey()
  id? = v4();

  constructor({ id }: Partial<User>) {
    this.id = id;
  }
}

Calls like em.getRepository(User).create({ id: ' fake-uuid-like-string' }) will fail with Cannot destructure property 'id' of 'undefined' as it is undefined.

Versions

Dependency	Version
node	v12.16.3
typescript	3.9.7
@mikro-orm/core	4.0.0-rc.4
@mikro-orm/postgresql	4.0.0-rc.4

[B4nan]

This use case was not really supported, and the error is not caused by that undefined in ctor params, but rather in your ctor implementation, as you rely on the ctor value, but ORM won't give you any if the parameter is not named as one of the properties.

I was recently thinking about this, and I think we should provide the full data object in the ctor param if there is something either not matching existing properties or not having a name (like your example), which should help in most cases.

Btw the reproduction like this is not really reproducing anything, as EntityFactory will never call the ctor if you provide all the PKs. Not talking about using initializer for the id property, as that will override the id from ctor anyway. To make the test really fail, I did add name: string property and used that in the ctor instead of id.