When working with TypeORM you might want to declare optional columns that do not have to be filled. An entity definition for such a use case might look like this:
@Entity()
class Foo {
...
@Column({ nullable: true })
bar?: string;
}
The entity Foo has a column bar which is optional. At first, this code seems sound and database entries can be created:
const foo = new Foo();
await repo.save(foo);
Now let’s try to update an existing entity by setting bar to undefined. The assumption is that the corresponding database value will be unset afterwards:
const foo = repo.findOne(...);
foo.bar = undefined;
await repo.save(foo);
Even though bar was set to undefined, the database value remains untouched. TypeORM is not designed to handle undefined values.
To address this, I suggest to make optional fields mandatory and to explicity define a null type. This prevents forgetting to set a field during an update. Adjust the column definition and the code to update an existing entity as follows:
bar: string | null;
const foo = repo.findOne(...);
foo.bar = null;
await repo.save(foo);