some more changes in configuration

lib/configuration.dart

 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:http/http.dart' as http;
-import 'dart:convert';
 import 'datamodel.dart';
 import 'sensorconnector.dart';
 
-
 class Configuration extends StatefulWidget {
   const Configuration({Key? key}) : super(key: key);
 
@@ -31,7 +28,9 @@ class _MyHomePageState extends State<Configuration> {
     //Start fetching all possible sensor data as soon as possible:
     futureCollections = connector.fetchCollections();
     futureEventTypes = connector.fetchEventTypes();
-    futureDevices = connector.fetchCollectionDevices(configuration.currentCollection.id);
+    if (configuration.currentCollection.id != -1) {
+      futureDevices = connector.fetchCollectionDevices(configuration.currentCollection.id);
+    }
     futureAuthToken = connector.getAuthToken(configuration.loginInformation.mail, configuration.loginInformation.password);
   }
   late Future<String> eventTypes;
@@ -99,6 +98,7 @@ class _MyHomePageState extends State<Configuration> {
                     collection if not initialized yet*/
                     if(configuration.currentCollection.id == -1){
                       configuration.currentCollection = configuration.collections[0];
+                      futureDevices = connector.fetchCollectionDevices(configuration.currentCollection.id);
                     }
 
                     return DropdownButtonFormField(
@@ -142,7 +142,6 @@ class _MyHomePageState extends State<Configuration> {
             },
           ),
           FloatingActionButton.extended(
-
             heroTag: null,
             tooltip: 'Select Collection and download corresponding devices',
             icon: const Icon(Icons.save),
@@ -153,29 +152,31 @@ class _MyHomePageState extends State<Configuration> {
                   //Update configuration with newly fetched data
                   futureDevices.then((value) => configuration.devices = value);
                   futureEventTypes.then((value) => configuration.eventTypes = value);
-
-                  //Update id and urn for the add event widget with some initial data
-                  events.currentEvent.id = configuration.devices[0].id;
-                  events.currentEvent.urn = configuration.devices[0].urn;
-                  events.currentEvent.description = '';
-                  events.currentEvent.label = '';
-                  events.currentEvent.type = configuration.eventTypes[0].name;
-
-                  var date = DateTime.now().toUtc();
-                  var isodata = date.toIso8601String();
-                  events.currentEvent.startDate = isodata;
-                  events.currentEvent.endDate = isodata;
-                  configuration.initialized = true;
-
-                  HapticFeedback.vibrate();
+                  print("Devices: " + configuration.devices.toString());  //Still empty on first execution Why?
+                  // TODO: Move fetchCollectionDevices to an own future and set configuration inside on finish!
+                  try {
+                    //Update id and urn for the add event widget with some initial data
+                    events.currentEvent.id = configuration.devices[0].id; //TODO: fix if devices are an empty list.
+                    events.currentEvent.urn = configuration.devices[0].urn;
+                    events.currentEvent.description = '';
+                    events.currentEvent.label = '';
+                    events.currentEvent.type = configuration.eventTypes[0].name;
+
+                    var date = DateTime.now().toUtc();
+                    var isodata = date.toIso8601String();
+                    events.currentEvent.startDate = isodata;
+                    events.currentEvent.endDate = isodata;
+                    configuration.initialized = true;
+
+                    HapticFeedback.vibrate();
+                    //TODO: display success
+                  } catch(e){
+                    throw Exception('Something went wrong try again');
+                  }
                 });
               });
 
-
-              //login();
-              //fetchEventTypes();
-              //updateDevices(configuration.currentCollection.id);
-              //HapticFeedback.vibrate();
+              //TODO: display failed here somehow
             },
           ),
         ],

lib/datamodel.dart

-import 'dart:convert';
-
-import 'package:shared_preferences/shared_preferences.dart';
-
 
 class Collection {
   int id;

lib/main.dart

 import 'package:flutter/material.dart';
-
 import 'datamodel.dart';
 import 'addevent.dart';
 import 'viewevents.dart';

lib/overview.dart

-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 
 class Overview extends StatelessWidget {

lib/viewevents.dart

 import 'dart:convert';
-
-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'datamodel.dart';
 import 'package:http/http.dart' as http;
@@ -318,11 +316,6 @@ class _ViewEvents extends State<ViewEvents> {
       ],
     );
   }
-
-
-
 }
 
-
-
 //TODO: allow editing fields here. Check validation of input value!
\ No newline at end of file