Flutterfire deleting item from database-CodePudding

I am trying to delete a specific item from a database given only its element values. However, I keep getting the error message "The type 'Stream<QuerySnapshot<Object?>>' used in the 'for' loop must implement Iterable" over the items.snapshot() section. What am I doing wrong there, because I thought that it would get me all the snapshots of the documents? The deleteName, Type, and Location are all String variables that I defined earlier

CollectionReference items = FirebaseFirestore.instance.collection('items');
 Object deleteUser() {
// Call the user's CollectionReference to add a new user
if (name != "" && type != "" && location != "") {

  for (var doc in items.snapshots()) {
    if (doc.data['name'] == deleteName &&
        doc.data['type'] == deleteType &&
        doc.data['location'] == deleteLocation) {
      doc.delete();
    }
  }
  return items;
} else {
  return "There was a null error";
}
   }

CodePudding user response：

Your code is a little confusing, if your getting items from Firestore, you will want to map it to an object for iterating through.

Item(
  String id; //Give an id value for document ID in firestore
  String name;
  String type;
  String location;
);

//Get Items
CollectionReference itemsCollection = FirebaseFirestore.instance.collection('items');
List<Item> items = itemsCollection.snapshots().map(itemsSnapshot)


//Map Items
List<Item> itemsSnapshot(QuerySnapshot snapshot) {
    return snapshot.docs.map((DocumentSnapshot doc) {
      Map<String, dynamic> data = doc.data() as Map<String, dynamic>;
      return Item(
        id: doc.reference.id, //this is your reference to firestore
        name: data['name'],
        type: data['type'],
        location: data['location'],
      );
     }).toList();
}

//Iterate through list of items
for(Item item in items){
  //do any checks you want here
  if(item.name == "Nobody"){
     //delete document
     itemsCollection.doc(item.id).delete();
  }
}

CodePudding user response：

Your items is a CollectionReference object, and calling snapshots() returns a Stream, which is you can't loop over with a for loop.

My guess is that you're looking to use get instead of snapshots, so that you can then await the result and process it:

CollectionReference itemsCol = FirebaseFirestore.instance.collection('items');
var itemsSnapshot = await itemsCol.get();

for (var doc in itemsSnapshot.docs) {
  ...
}