Firebase Cloud Firestore 查询找不到我的文档

Question

Here's a picture of my data:

I'm trying to get that document. This works:

var docRef = db.collection('users').doc('jPDKwHyrFNXNTFI5qgOY');
docRef.get().then(function(doc) {
  if (doc.exists) {
    console.log("Document data:", doc.data());
  } else {
    console.log("No such document!");
  }
}).catch(function(error) {
  console.log("Error getting document:", error);
});

It returns:

Ie, if I know the document's key I can get the document.

This doesn't work:

db.collection('users').where('uid', '==', 'bcmrZDO0X5N6kB38MqhUJZ11OzA3')
.get().then(function(querySnapshot) {
  if (querySnapshot.exists) {
    console.log(querySnapshot.data);
  } else {
    console.log("No such document!");
  }
})
.catch(function(error) {
  console.log("Error getting document: ", error);
});

It just returns No such document! What's wrong with my query?

Answer 1

The difference in your two requests is that in the first case you are retrieving one document which gives you a DocumentSnapshot which has the exists property and the data() method.

In the second case you do a query, which gives you a QuerySnapshot that has to be handled differently from a DocumentSnapshot . Instead of a single document you get a list/collection of documents. You can check if data has been retrieved using the empty or size properties, and then go through the results using the forEach method or going through the docs array:

db.collection('users').where('uid', '==', 'bcmrZDO0X5N6kB38MqhUJZ11OzA3')
.get().then(function(querySnapshot) {
  if (querySnapshot.size > 0) {
    // Contents of first document
    console.log(querySnapshot.docs[0].data());
  } else {
    console.log("No such document!");
  }
})
.catch(function(error) {
  console.log("Error getting document: ", error);
});

Answer 2

I had the same problem with my project. First of all there have to be an object in your database that match with the .where('objectid',==, 'object.id') then it is possible to get your data to loop. Like querysnapshot.docs.forEach((d) => d.data());