Firestore Getting documents id from collection

I'm trying to retrieve my documents with id but can't figure it out.
Currently I retrieve my documents like this :

const racesCollection: AngularFirestoreCollection<Races> = this.afs.collection('races');
return racesCollection.valueChanges();

I do get my documents list perfectly, however there is no doc id with them.

How can I retrieve it for each document ?

For angular 8 and Firebase 6 you can use the option id field

      getAllDocs() {
           const ref = this.db.collection('items');
           return ref.valueChanges({idField: 'customIdName'});
      }

this adds the Id of the document on the object with a specified key (customIdName)

To obtain the id of the documents in a collection, you must use snapshotChanges()

    this.shirtCollection = afs.collection<Shirt>('shirts');
    // .snapshotChanges() returns a DocumentChangeAction[], which contains
    // a lot of information about "what happened" with each change. If you want to
    // get the data and the id use the map operator.
    this.shirts = this.shirtCollection.snapshotChanges().map(actions => {
      return actions.map(a => {
        const data = a.payload.doc.data() as Shirt;
        const id = a.payload.doc.id;
        return { id, ...data };
      });
    });

Documentation https://github.com/angular/angularfire2/blob/7eb3e51022c7381dfc94ffb9e12555065f060639/docs/firestore/collections.md#example

I've finally found the solution. Victor was close with the doc data.

const racesCollection: AngularFirestoreCollection<Race>;
return racesCollection.snapshotChanges().map(actions => {       
  return actions.map(a => {
    const data = a.payload.doc.data() as Race;
    data.id = a.payload.doc.id;
    return data;
  });
});

ValueChanges() doesn't include metadata, therefor we must use SnapshotChanges() when we require the document id and then map it properly as stated here https://github.com/angular/angularfire2/blob/master/docs/firestore/collections.md

For angular6+

    this.shirtCollection = afs.collection<Shirt>('shirts');
    this.shirts = this.shirtCollection.snapshotChanges().pipe(
        map(actions => {
        return actions.map(a => {
            const data = a.payload.doc.data() as Shirt;
            const id = a.payload.doc.id;
            return { id, ...data };
        });
        })
    );