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Problem with functions in dart
I am using appwrite 1.3.7 , when writing functions in dart , the function not executing "print" commands inside "if" statements or after".then" or in functions other than "start" function
TL;DR
The user is experiencing issues with functions in Dart, specifically with the `res.json()` function returning before the `then` callbacks are executed. They are advised to read up on how futures work and to await the `listDocuments` call. Additionally, the user shares a code snippet and mentions that `print` commands are not executing properly in certain parts of the code. The user is using Appwrite 1.3.7 framework. 
your function might be returning before those then callbacks are being executed. it would help if you shared your actual code
TypeScript
import 'dart:convert';
import 'package:dart_appwrite/dart_appwrite.dart';
import 'car_model.dart';
Future<String?> isAdvertiserExists({required String userId, required Databases db}) async {
String? res;
try {
db.listDocuments(
databaseId: "VipcarDatabaseV3",
collectionId: "Advertiser",
queries: [
Query.equal('user_id', [userId]),
]).then((adv){
if(adv.documents.isNotEmpty){
res= adv.documents[0].$id;
print("Document id : ${adv.documents[0].$id}");
}else{
print("Document not found");
res = null;
}
});
} catch (e) {
print(e.toString());
print("isAdvertiserExists function error");
}
return res;
}
Future<void> start(final req, final res) async {
final client = Client();
final database = Databases(client);
if (req.variables['APPWRITE_FUNCTION_ENDPOINT'] == null ||
req.variables['APPWRITE_FUNCTION_PROJECT_ID'] == null ||
req.variables['APPWRITE_FUNCTION_API_KEY'] == null) {
print(
"Environment variables are not set. Function cannot use Appwrite SDK.");
} else {
client
.setEndpoint(req.variables['APPWRITE_FUNCTION_ENDPOINT'])
.setProject(req.variables['APPWRITE_FUNCTION_PROJECT_ID'])
.setKey(req.variables['APPWRITE_FUNCTION_API_KEY'])
.setSelfSigned(status: true);
}
final String appUserId = req.variables["APPWRITE_FUNCTION_USER_ID"];
bool resultCode = true;
String message = "ok";
bool? adverOk;
late CarObject car;
try {
car = CarObject.fromJson(jsonDecode(req.payload));
print(car.carCategoryId);
} catch (e) {
print(e.toString());
}
car.advertiserId = appUserId;
isAdvertiserExists(userId: appUserId, db: database).then((res) {
if (res != null) {
adverOk = true;
} else {
adverOk = false;
}
});
res.json({
"code": resultCode,
"message": message,
"attr": adverOk,
});
}
In this function i am receiving data from user then define model for that data, then trying to find the document that has user id as attribute.
You have to await the list documents call
You should probably read into how futures work some more too to get a better understanding of how they work
In short, the res.json() is called and your function returns before any of the thens get executed
