如果您只知道一个字段（firestore）的数据，如何找到文档的id？

Question

I have a problem. I have to get the automatically generated id of a document with the help of the data of a field which is in the document from which I have to find out the id.

To make it more logical, an example: As you can see on the screenshot, I have the 'seller' collection, which in turn has different documents that contain different data. The app only knows what the name is, but not from which field it takes the name (eg name: 'Paul'). The task is that the app now has to find out which document the name Paul comes from. In this case it would be ' 4wHJZ3I2hAqbCFP0323A '.

I saw on the inte.net that there is a filter option for firestore, but I don't know how I can use this to get the ID of the document. Can anyone help me?

Answer 1

You need to do the following:

final firestoreInstance = FirebaseFirestore.instance;
firestoreInstance
    .collection("seller")
    .where("name", isEqualTo: "Paul")
    .get()
    .then((value) {
  value.docs.forEach((result) {
    print(result.id);
  });
});

with async/await:

getData() async {
 final firestoreInstance = FirebaseFirestore.instance;
 final result = await firestoreInstance.collection("users").where("name", isEqualTo: "Paul").get();
 result.docs.forEach((result) {
    print(result.id);
  });
});

result.id will give you the document id where name = Paul .