Include the document id as a field id in firestore

Heres what i am trying to achieve i want a unique id field for every document in my database and i want that unique id to the same as the document id.

Example:

documents:       data:

eBgdTRE123       id:'eBgdTRE123'
                 name:'Jhon Doe'
                 job:'Programmer'     

i want i databse to have this structure, now i got two ideas to achieve this

1: to use cloud function and have onCreate listener and everytime theres a new document grab document and set the id field and update it heres how i am doing it

exports.addDocIdToField = 

functions.firestore.document('collectionname/{docID}').onCreate((snap,context) => {
    const id = context.params.docID;
    return admin.firestore().collection('collectionname')
        .doc(id).set({ id: snap.id }, { merge: true })
        .then(() => {
            return null;
        })
        .catch((error) => {
            return null;
        });
})

2: to use the above kind of method on document creation. add a new document as soon as that document is added get the newly added document and update its id

both of them work but my question is can i rely on this kind of operation? i mean if the id is by any means undefined it can cause an error further in the app.

or if there are other ways to achieve this?