CODEWITHSUNDEEP
javascriptreactjsfirebasegoogle-cloud-firestore
Rupali Jain
Rupali Jain

Reputation: 3

Cannot fetch list of UIDs inside "users" collection in firebase using reactjs

constructor(props) {
    super(props);
    this.state = {
      users:[]
    };
  }

//method to get the data from users collection
  async componentDidMount() {
      const db = firebase.firestore();
      db.collection("users")
      .get()
      .then(querySnapshot => {
          const data = querySnapshot.docs.map(doc => doc.data());
          console.log(data);
          this.setState({ users: data });
      })
      .catch( err =>{
          console.log(err);
      });
    }

this function returning an empty error i want to print list of users uid

firebase snippet

here i have users collection and inside it i have retailers collection and its document

Upvotes: 0

Views: 63

Answers (3)

Shaurya Vardhan Singh
Shaurya Vardhan Singh

Reputation: 684

The data method on querySnapshot.docs gets the data now to get the id of each document you need to add access the id property as UID is stored in id property

async componentDidMount() {
      const db = firebase.firestore();
      db.collection("users")
      .get()
      .then(querySnapshot => {
          const data = querySnapshot.docs.map(doc => doc.data().id);
          console.log(data);
          this.setState({ users: data });
      })
      .catch( err =>{
          console.log(err);
      });
    }

Upvotes: 0

Frank van Puffelen
Frank van Puffelen

Reputation: 598740

This line in your current code querySnapshot.docs.map(doc => doc.data()) takes the data of each document. But you're keeping the UID in the ID of each document, so you'll want to use:

  const db = firebase.firestore();
  db.collection("users")
  .get()
  .then(querySnapshot => {
      const data = querySnapshot.docs.map(doc => doc.id);
      console.log(data);
      this.setState({ users: data });
  })
  .catch( err =>{
      console.log(err);
  });

Update: As Doug pointed out in his answer, if there are no actual user documents, your get() call will not return it. I highly recommend creating user documents, even if it's just an empty one.

For now, the only way to get the UID would be to load all retailers for all users, and then use those results to get the ID of the parent documents:

  const db = firebase.firestore();
  db.collectiongroup("retailers")
  .get()
  .then(querySnapshot => {
      querySnapshot.forEach((doc) => {
          console.log("retailed "+doc.id+" for user "+doc.ref.parent.parent.id);
      });
  })
  .catch( err =>{
      console.log(err);
  });

You'll have to deduplicate the UIDs, but that will leads to getting the UIDs.

But you'll be loading all retailers for all users this way, so as said, I highly recommend storing a small/empty user document instead.

Upvotes: 0

Doug Stevenson
Doug Stevenson

Reputation: 317392

One thing you have to realize here is that your users collection contains no documents. The document IDs are shown in italics, which means that there is no document here. The IDs are visible because there is a nested subcollection under each document. They are shown like this in the console so that you can click through and navigate to the nested subcollection, despite the document being missing.

If you want to list users with a query, you will have to actually create documents in the users collection. They can be empty if you don't have any information. But you do need actual documents in the users collection in order for anything to show up in a query.

Upvotes: 3

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