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Firebase Firestore Guides show how to iterate documents in a collection snapshot with forEach:
db.collection("cities").get().then(function(querySnapshot) { querySnapshot.forEach(function(doc) { console.log(doc.id, " => ", doc.data()); }); }); I imagined it would support map as well, but it doesn't. How can I map the snapshot?
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There are three ways to retrieve data stored in Cloud Firestore. Any of these methods can be used with documents, collections of documents, or the results of queries: Call a method to get the data once. Set a listener to receive data-change events.
You can listen to a document with the onSnapshot() method. An initial call using the callback you provide creates a document snapshot immediately with the current contents of the single document. Then, each time the contents change, another call updates the document snapshot.
snapshotChanges() Metadata provides you the underyling DocumentReference , document id, and array index of the single document. Having the document's id around makes it easier to use data manipulation methods.
The answer is:
querySnapshot.docs.map(function(doc) { # do something }) The Reference page for Firestore reveals the docs property on the snapshot.
docs non-null Array of non-null firebase.firestore.DocumentSnapshot
An array of all the documents in the QuerySnapshot.
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Got pretty sick and tired of Firestore returning stuff in their classes or whatever. Here's a helper that if you give it a db and collection it will return all the records in that collection as a promise that resolves an actual array.
const docsArr = (db, collection) => { return db .collection(collection) .get() .then(snapshot => snapshot.docs.map(x => x.data())) } ;(async () => { const arr = await docsArr(myDb, myCollection) console.log(arr) })() If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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