Cloud Firestore QuerySnapshot Where function field not supported - flutter

Question

I am using Cloud Firebase on my android app and I want to filter my documents using where function to avoid unnecessary billing cost, my problem is instead of using document field inside my where function I prefer model to filter my data due to multiple advantage, then I try below code, but it trough error of
"'field is String || field is FieldPath || field == FieldPath.documentId': Supported [field] types are [String] and [FieldPath].,"
I try this
final authPhoneNo = Utils.formatPhoneNo(phoneNo!);
CollectionReference receiptCollection = FirebaseFirestore.instance
.collection('example');
QuerySnapshot querySnapshot;
querySnapshot = await receiptCollection.orderBy('Date', descending: true).where((e){
Utils.formatPhoneNo(MainData.fromJson(e.data()).userPhoneNo!);
}, isEqualTo: authPhoneNo).get();
formatPhoneNo
static formatPhoneNo(String phoneNo) => phoneNo.replaceAll(RegExp(r"\D"), "")
.substring(
(phoneNo.replaceAll(RegExp(r"\D"), "").length) - 9,
(phoneNo.replaceAll(RegExp(r"\D"), "").length)
);
It through error on where((e)
'field is String || field is FieldPath || field == FieldPath.documentId': Supported [field] types are [String] and [FieldPath].

Answer 1

From the code you provided, I see that you want to filter data using where and a formatter function formatPhoneNo, but this is not how it works according to the official documentation:
// Create a reference to the cities collection
final citiesRef = db.collection("cities");
// Create a query against the collection.
final query = citiesRef.where("state", isEqualTo: "CA");
As you can see, the first parameter on the where clause refers to the field you want to filter and the second one refers to the query operation you want to perform (in this case, isEqualTo) and the reference value (in the example, the string "CA").
In your case, the right way to do the query would be as follows:
querySnapshot = await receiptCollection.where('phoneNo', isEqualTo: authPhoneNo).get();
To avoid the use of a formatter, which leads to unnecessary processing time every time it is called and; in this case could lead to format every result until the desired value matches the condition if its done without the where Firebase function, I would recommend to sanitize your data before saving it to Firebase as recommended in this article:
2. Standardize phone number formatting
When you capture telephone data, either directly from the customer or via an ingress from a data supplier, you should standardize the telephone number format. Ideally, you should use the industry-standard E.164 format
...
If you prefer to display a telephone number in a nice to read human format you can still store the number in your database in E.164 format but present the number on the screen in a friendly format.
Doing this way, you could filter your data saved in Firebase using simple and compound queries as shown in the Firebase documentation.