entitySkipConstructor not working

[francescosalvi]

entitySkipConstructor not working as expected/documented

See #7770, #1772

Expected Behavior

By setting entitySkipConstructor connection option, one is able to define an Entity class with strict constructor property initialization, even using object-type destructuring, e.g.:

type SomeEntityConstructorArgs = {
  readonly foo: string;
};

@Entity()
export class SomeEntity {

  @Column()
  readonly foo: string;

  constructor(args: SomeEntityConstructorArgs) {
    const { foo } = args;

    this.foo = foo;
  }
}

Actual Behavior

Running migration:run, or bootstrapping a NestJS app leveraging TypeORM, breaks with:

TypeError: Cannot destructure property 'foo' of 'args' as it is undefined.
    at null.SomeEntity (/app/src/entity/SomeEntity.ts:57:13)
    at EntityMetadata.EntityMetadata.create (/app/node_modules/typeorm/metadata/src/metadata/EntityMetadata.ts:534:23)
    at EntityMetadataValidator.EntityMetadataValidator.validate (/app/node_modules/typeorm/metadata-builder/src/metadata-builder/EntityMetadataValidator.ts:118:47)
    at null.<anonymous> (/app/node_modules/typeorm/metadata-builder/src/metadata-builder/EntityMetadataValidator.ts:46:56)

Steps to Reproduce

(see above): simply define an Entity constructor with object destructuring assignment (I actually expect a failure even with strict undefined checks of scalar arguments).

My Environment

Dependency	Version
Operating System	Linux
Node.js version	v16.13.1
Typescript version	4.5.2
TypeORM version	0.2.41
nestjs/typeorm	8.0.2

Was reproduced with a MySQL connection, but I believe the error is unrelated to the driver in use.

Are you willing to resolve this issue by submitting a Pull Request?

• ✅ Yes, I have the time, and I know how to start.
• ✖️ Yes, I have the time, but I don't know how to start. I would need guidance.
• ✖️ No, I don’t have the time, but I can support (using donations) development.
• ✖️ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.

Root cause / Possible fix

Locally I applied the patch below which seems to have solved the issue. Perhaps this point in code was an oversight? I see in fact than in most if not all instances where EntityMetadata.create is invoked, { fromDeserializer: true } is passed as well.

diff --git a/node_modules/typeorm/metadata-builder/EntityMetadataValidator.js b/node_modules/typeorm/metadata-builder/EntityMetadataValidator.js
index 9bb557e..d454d4b 100644
--- a/node_modules/typeorm/metadata-builder/EntityMetadataValidator.js
+++ b/node_modules/typeorm/metadata-builder/EntityMetadataValidator.js
@@ -102,7 +102,7 @@ var EntityMetadataValidator = /** @class */ (function () {
                 throw new error_1.TypeORMError("Character set specifying is not supported in Sql Server");
         }
         // check if relations are all without initialized properties
-        var entityInstance = entityMetadata.create();
+        var entityInstance = entityMetadata.create(undefined, { fromDeserializer: true });
         entityMetadata.relations.forEach(function (relation) {
             if (relation.isManyToMany || relation.isOneToMany) {
                 // we skip relations for which persistence is disabled since initialization in them cannot harm somehow