Error "function is empty or cannot be parsed" while saving custom function in FlutterFlow

Question

I have a custom function in my FlutterFlow app with this code:

import 'dart:convert';
import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:intl/intl.dart';
import 'package:timeago/timeago.dart' as timeago;
import '/flutter_flow/custom_functions.dart';
import '/flutter_flow/lat_lng.dart';
import '/flutter_flow/place.dart';
import '/flutter_flow/uploaded_file.dart';
import '/backend/schema/structs/index.dart';
import 'package:http/http.dart' as http;

Future<List<double>?> getLatLngFronAddress(String address)  async{
  /// MODIFY CODE ONLY BELOW THIS LINE

  final apiKey =
      'YOUR_API_KEY'; // Inserisci qui la tua API Key oppure usa un secret param
  final url = Uri.parse(
      'https://maps.googleapis.com/maps/api/geocode/json?address=${Uri.encodeComponent(address)}&key=$apiKey');

  final response = await http.get(url);

  if (response.statusCode == 200) {
    final data = json.decode(response.body);

    if (data['status'] == 'OK') {
      final location = data['results'][0]['geometry']['location'];
      final lat = location['lat'];
      final lng = location['lng'];
      return [lat, lng];
    } else {
      //debugPrint('Geocoding failed: ${data['status']}');
    }
  } else {
    //debugPrint('HTTP error: ${response.statusCode}');
  }
  return null;

  /// MODIFY CODE ONLY ABOVE THIS LINE
}

flutterflow release an error:

but flutter flow doesn't save the function whith the messagge:

The function is empty or cannot be parsed. Make sure not to modify code outside of the designated area.

I need import the http class and make the function async/future.

Since you solved the problem in the way I described in my answer below: What should I do when someone answers my question? — Frank van Puffelen
– Frank van Puffelen, Commented Apr 22 at 17:15

Frank van Puffelen · Accepted Answer · 2025-04-20 20:26:48Z

1

Custom Functions in FlutterFlow cannot be async and cannot perform custom imports. The template code tries to make that clear by including these markings:

/// MODIFY CODE ONLY BELOW THIS LINE
...
/// MODIFY CODE ONLY ABOVE THIS LINE

Ignoring these instructions leads to the type of error you're getting.

Following the instructions means that Custom Functions are limited to performing synchronous operations on their inputs with the functionality that FlutterFlow already imports.

To perform the type of action you want to do, you'll typically use a Custom Action, which can be asynchronous (in fact: most actions are async) and perform custom imports.

edited Apr 20 at 20:26

answered Apr 20 at 20:18

Frank van Puffelen

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