Get all documents from a collection

0
votes

I want to get all the documents from a collection, and then with them, get their id. Here how my collections is user collection It's only one collections with multiple documents. I try this but it doesn't work :

let userRef = admin.firestore().collection('users');
      return userRef.get().then(querySnapshot => {
        let docs = querySnapshot.docs;
        for (let doc of docs) {
           console.log(doc.id);
        }
        return true;
      });

UPDATE

What i was really trying to do, was to get all the documents id of a parent collections, so that i can use them to iterate in each of these documents which contain a subcollection.

So when i do the same thing who worked for the user collection up here, in this case with a parent collection which have documents id which contain a subcollection, it doesn't work. It's like my collection have no documents in it.

let savedRef = await admin.firestore().collection('saved');
        return savedRef.get().then(querySnapshot => {
          console.log(querySnapshot);
          let docs = querySnapshot.docs;
          for (let doc of docs) {
             console.log(doc.id);
          }
          return true;
        });

saved collection which contain documents with a subcollection

Do you have any idea why ? Thank you,

2
node.jsfirebasegoogle-cloud-firestoregoogle-cloud-functions
What does your code that is different than what you expect? It looks like it would work. – Doug Stevenson
Yes it worked, but only when it's one collections with no nested subcollection. What I was really trying to do was to get all the documents id from the parent collection so that i can iterate in each subcollections in the document of the parent collection. – Jeremy Dormevil

2 Answers

4
votes

Yes, querySnapshot can be easily iterated itself and get what you want. This is how I normally iterate Firestore query Snapshots:

//I like to separate DB instance for re-utilization
var db = admin.firestore()

//Also a good practice to separate reference instance
var usersReference = db.collection("users");

//Get them
usersReference.get().then((querySnapshot) => {

    //querySnapshot is "iteratable" itself
    querySnapshot.forEach((userDoc) => {

        //userDoc contains all metadata of Firestore object, such as reference and id
        console.log(userDoc.id)

        //If you want to get doc data
        var userDocData = userDoc.data()
        console.dir(userDocData)

    })

})
1
votes

In order to iterate through subcollection elements inside a specific document, you can do the following:

db.collection("ParentCollection").doc("DocumentID").collection("SubCollection").get()
.then((querySnapshot) => {
      ...
  });
});

If you want to iterate through all the Sub Collections of all the Parent Collections you can do the following:

db.collection("ParentCollection").get().then((querySnapshot) => {
  querySnapshot.forEach((document) => {
    document.ref.collection("SubCollection").get().then((querySnapshot) => {
      ...
    });
  });
});

EDIT: Adding the exact code sample that worked for me:

const app = express();
const Firestore = require('@google-cloud/firestore');

const db = new Firestore({
  projectId: 'my-project-id',
  keyFilename: '/path/to/service/account/key/file.json',
});

app.get('/', async (req, res) => {
  db.collection("ParentCollection").get().then((querySnapshot) => {
    // console.log(querySnapshot)
    querySnapshot.forEach((document) => {
      document.ref.collection("SubCollection").get().then((querySnapshot) => {
        console.log(querySnapshot)
        querySnapshot.forEach((document) => {
          console.log(document.id, '=>', document.data());
        });
      });
    });
  });
  res
  .status(200)
  .send('Hello, world!\n')
  .end();
});