import 'package:flutter/foundation.dart';
import 'package:postgres/postgres.dart';
  PostgreSQLConnection(String s, int i, String t,     {required String username, required String password}) {}
  void main() async {
   // Create an instance of PostgreSQLConnection with connection parameters
   final connection = PostgreSQLConnection(     '91.225.104.133',
     5432,// Port number 
    'homeservice', 
     username: 'homeservice',
     password: 'SrVEJGj2DNQo',   );
    try {
     // Open the connection
     await connection.open();
     print('Connected to PostgreSQL database!');
      // Perform database operations here
     // For example, execute a query
     final results = await connection.query('SELECT * FROM servicemodels');
     print('Query results: $results');
   } catch (e) { 
    print('Error connecting to database: $e');
   } finally {
     // Always remember to close the connection when done
     await connection.close();
     print('Connection closed.');   }  }  

this is the code i wrote for the connection between dart program and postgresql but it keeps giving the same error since the beginning :

Connecting to VM Service at ws://127.0.0.1:51948/EqB2XheM_3U=/ws
Error connecting to database: NoSuchMethodError: 'open'
Dynamic call of null.
Receiver: null
Arguments: []

What should i do? its due tomorrow and i have to commit the db.dart file which i tried to write to connection on into the original file.