There's a comment on that on #2267

I have a bit of a workaround for this that can be used until the withConverter as added as an extension to the normal API.

The AngularFirestore.collection method accepts a CollectionReference as well as a string. So, you can first create a CollectionReference complete with the converter applied using the plain old firestore library and then provide that reference to the collection method.

getCollectionWithConverter(): CollectionReference {
 return this.db.firestore.collection("Courses").withConverter(this.converter)
}
createCourse(course: Course) {
 return this.db.collection(this.getCollectionWithConverter()).add(course);
}

My converter (injected as "converter") then implements the FirestoreDataConverter interface.

Works without any issues.

I have a bit of a workaround for this that can be used until the withConverter as added as an extension to the normal API.

The AngularFirestore.collection method accepts a CollectionReference as well as a string. So, you can first create a CollectionReference complete with the converter applied using the plain old firestore library and then provide that reference to the collection method.

getCollectionWithConverter(): CollectionReference {
 return this.db.firestore.collection("Courses").withConverter(this.converter)
}
createCourse(course: Course) {
 return this.db.collection(this.getCollectionWithConverter()).add(course);
}

My converter (injected as "converter") then implements the FirestoreDataConverter interface.

Works without any issues.

worked for me, thank you !

While @IainAdamsLabs is correct I'd like to point out that using .valueChanges({idField:'id'}) or something like that will kill the class you created with the transformer as it is converted to an object here https://github.com/angular/angularfire/blob/master/src/firestore/collection/collection.ts#L113-L117
A better way to achieve this would be, to use snapshot.id in the converter (fromFirestore) which will hold the id regardless.