Angularfire: Firestore: How to check if document exists, and create one if it doesn't

[avilao]

*AngularFireStore:

Is there a way to check if a document already exists in the database?

Couldn't find an example.

Thank you

[larssn]

Don't think you can do it with AFS, and might have to rely on the underlying framework:

this.afs.firestore.doc('/users/asfaf').get()
      .then(docSnapshot => {
        if (docSnapshot.exists) {
          // do something
        }
      });

[jamesdaniels]

this.afs.doc('/path').take(1).do(d => d.payload.exists())

As of 5.0 rc3 empty sets/docs should be handled correctly.

I am working on an API to make return or create easier.

[ButhSitha]

@jamesdaniels I import the operator take already but i got error
i can't use doc with take operator.

[dhawken]

I'm doing it manually - hopefully there is a better way?

  this.dataDoc = this.myDataCollectionRef.doc(id); 

  this.data = this.dataDoc.snapshotChanges().map(action => {
        if (action.payload.exists === false) {
            return null;
        } else {
            const data = action.payload.data() as Whatever;
            const id = action.payload.id;
      return { id, ...data };;  
   });

Might be incorrect usage of snapshotChanges(), but its able to determine if something is there. If you wanted to manually create it, I believe you could do that once you've determined it doesn't exist.

[sneurlax]

Just popping in to report that neither take() nor do() work (exist) for me on AngularFirestoreDocument

[sneurlax]

Currently handling this by attempting an update and setting on error as such:

this.afs.doc(`users/${uid}`)
  .update({data})
  .then(() => {
    // update successful (document exists)
  })
  .catch((error) => {
    // console.log('Error updating user', error); // (document does not exists)
    this.afs.doc(`users/${result.uid}`)
      .set({data});
  });

[vaurelios]

@jamesdaniels example is missing somethings:

• .snapshotChanges()
• exists isn't a function, is a property.

So,

this.afs.doc('/path').snapshotChanges().take(1).do(d => d.payload.exists)

[Vicky443]

i check simply , not sure if that is the right way to do ..

const userRef: AngularFirestoreDocument = this.afs.doc(users/${user.uid});
userRef.valueChanges().subscribe(res=>{
if(res){
// do your perform
}
} );

[mk4yukkalab]

And if i need a query like : this.afs.collection('users', ref => ref.where('email', '==', email)) how i can do that?

[buchmiller]

Here's a variation of @sneurlax's example:

//Create an empty document, or do nothing if it exists.
this.afs.doc('users/sam').set({ }, { merge: true });

//Create a document with name property set to 'Sam'.
//If document already exists, it will still set the name property to 'Sam'
this.afs.doc('users/sam').set({ name: 'Sam' }, { merge: true });

[Zufarsk8]

@buchmiller
But by doing so, it will be a write in the document.
A write in the document is more costly in terms of pricing according to firebase pricing.
If we can read before we write it will be more cost efficient :)

[olanRay94]

How about searching 2 parameters, like username and email?
I am looking for username and email that I type in input.

I think it could be in 2 ways:

1. Maybe we can do all in one query in where clause using OR statement. I am not sure if firestore support it.

2. I think we can search the username first. If it return null, we continue search the email. I am looking for this possible way. Any suggestion?

[math-a3k]

FTR: https://angularfirebase.com/lessons/firestore-advanced-usage-angularfire/#4-Upsert-Update-or-Create-Method

// *** Usage
this.db.upsert('notes/xyz', { content: 'hello dude'})
// *** Code
upsert<T>(ref: DocPredicate<T>, data: any) {
  const doc = this.doc(ref).snapshotChanges().take(1).toPromise() 
  return doc.then(snap => {
    return snap.payload.exists ? this.update(ref, data) : this.set(ref, data)  })
}

[jwv]

You can use

db.doc('collectionName/documentId').ref.get().then((documentSnapshot) => {
  console.log(documentSnapshot.exists);
});

[miglrodri]

Hello,

I am using firestore from firebase(npm) and the property .exists was not available on the querySnapshot:

https://firebase.google.com/docs/firestore/query-data/get-data

db.collection("cities").get().then(function(querySnapshot) {
    querySnapshot.forEach(function(doc) {
        // doc.data() is never undefined for query doc snapshots
        console.log(doc.id, " => ", doc.data());
    });
});

querySnapshot in that context have a property .empty that I use to know if I get a document or not from the query. Hope this helps too.

[Vino16491]

@mk4yukkalab do you got workaround to ur concern

And if i need a query like : this.afs.collection('users', ref => ref.where('email', '==', email)) how i can do that?

[Hanan0o0]

And if i need a query like : this.afs.collection('users', ref => ref.where('email', '==', email)) how i can do that?

do you know how do that ??

[Hanan0o0]

@mk4yukkalab do you got workaround to ur concern

And if i need a query like : this.afs.collection('users', ref => ref.where('email', '==', email)) how i can do that?

do you know how do that ??

[hafizmowais]

firestore
.collection('YourCollection')
.doc('YourDocumentID').set(
{a: {b: {c: true}}},
{merge: true}
)

This one should work

[JeffGreat]

@mk4yukkalab @Hanan0o0 @Vino16491
in angular 6 I manage like that

this.afs.collection('users', (ref) => ref.where('email', '==', email).limit(1)).get().subscribe(users => { if(users.size >= 0) ...do smthg })

[funct7]

Currently handling this by attempting an update and setting on error as such:

this.afs.doc(`users/${uid}`)
  .update({data})
  .then(() => {
    // update successful (document exists)
  })
  .catch((error) => {
    // console.log('Error updating user', error); // (document does not exists)
    this.afs.doc(`users/${result.uid}`)
      .set({data});
  });

Trying to do something similar in iOS. I think this should be done in a transaction though because there's plenty of time for data to be written with the ID between the update response and the set. Also, I'm questioning whether this is a good solution since we're using an error in order to proceed.

[xgenem]

@larssn solution still works as of date.

[yuricamara]

@buchmiller
But by doing so, it will be a write in the document.
A write in the document is more costly in terms of pricing according to firebase pricing.
If we can read before we write it will be more cost efficient :)

Are you sure? For me it makes more sense, not be a cost in case of update. So, the cost will be the same as @sneurlax method.

[vasiledoe]

For Android in Kotlin:
````
fun insertOrUpdate() {
val mapFields = hashMapOf(
"key1" to "val1",
"key2" to "val2",
"key3" to "val3"
)

    val dbInstance = FirebaseFirestore.getInstance()

    val docRef: DocumentReference = dbInstance.collection("my_collection_id")
        .document("my_doc_id")

    docRef.get()
        .addOnSuccessListener {

            if (it.exists()) {
                docRef.update(mapFields)
                    .addOnSuccessListener { }
                    .addOnFailureListener { }

            } else {
                docRef.set(mapFields)
                    .addOnSuccessListener { }
                    .addOnFailureListener { }
            }
        }
        .addOnFailureListener { }
}

[MikeC711]

And if i need a query like : this.afs.collection('users', ref => ref.where('email', '==', email)) how i can do that?

I am not an expert so there may be better ways, but here is what I did in that situation:
this.afs.collection('eicpeople', ref => ref.where('familyKey', '==', person.familyKey))
.valueChanges().pipe(take(1)).subscribe(matchingRecs => {
if (matchingRecs.length > 0) // this is my equivalent to exists
else // this is no match

[jluz88]

Maybe a bit late, but this worked for me for a web app.

db.collection('users') .where('user_id', '==', user.id) .get() .then(querySnapshot => { if(querySnapshot.docChanges().length === 0){ //Add new user to DB db.collection('users').add( user ); } }).catch((err) => { console.log(err); });

[kylebradshaw]

The way I went about this a combo of creating my own unique ID based on the data by using a sha library (js-sha256), just JSON.stringify(data) to get your id then follow the approach above.

const sha = sha256(JSON.stringify({...data})).substring(0, 10);
this.db.doc(`${DATA}/${sha}`).set(data, {merge: true})

Data is always overwritten.

[Awais-mohammad]

Don't think you can do it with AFS, and might have to rely on the underlying framework:

this.afs.firestore.doc('/users/asfaf').get()
      .then(docSnapshot => {
        if (docSnapshot.exists) {
          // do something
        }
      });

.then is not applicable after .get or valuechanges

[Awais-mohammad]

I am also trying to find a solution for angular 8

[AbhiShrek]

All these code examples which use "docSnapshot.exists" checking, arent they forgetting that this is not a transaction, so it can not guarantee that by the time the client find out that doc does not exist and it triggers a create new doc, someone else might have created that doc, in between get() and set() calls ? (although its probability is less but not zero)

[davecoffin]

Thought Id share this...I am doing it like so:

const docRef = this.db.collection("user_flags").doc(this.user.id);
docRef.get().subscribe(doc => {
  docRef[doc.exists ? 'update' : 'set']({
    exampleFlag: true
  })
})

any objections? If the doc exists it uses update, otherwise set.