update: loading from file if no internet connection

app/lib/consts.dart

@@ -17,7 +17,7 @@ List<Measurement> selectedMarkerList = [];
 LatLng mapCenter = LatLng(60.8000, 10.8471);
 DateTime ?lastUpdate; // Last time data was fetched from server
 List<String> lakeSearchOptions = []; // Init empty
-bool internetConnection = true;
+bool internetConnection = false;
 
 // Font settings
 const textColor = Colors.white;

app/lib/controller/network_controller.dart

@@ -18,6 +18,8 @@ class NetworkController extends GetxController {
 
     // If no network connection, show snack-bar
     if (connectivityResult == ConnectivityResult.none) {
+      internetConnection = false;
+
       Get.rawSnackbar(
         messageText: Text(
           'No internet connection. The displayed information may be outdated!',
@@ -35,6 +37,8 @@ class NetworkController extends GetxController {
         snackStyle: SnackStyle.GROUNDED,
       );
     } else {
+      internetConnection = true;
+      
       if (Get.isSnackbarOpen) { // Close snack-bar upon establishing internet connection
         Get.closeCurrentSnackbar();
       }

app/lib/server_requests/fetch_markers.dart

@@ -62,18 +62,23 @@ Future<FetchResult> fetchMeasurements() async {
 }
 
 Future<FetchResult> loadSavedData() async {
-  // Get latest saved data from file if the server does not respond
-  Directory appDocumentsDirectory = await getApplicationDocumentsDirectory();
-  String filePath = '${appDocumentsDirectory.path}/last_data.json';
+  try {
+    // Get latest saved data from file if the server does not respond
+    Directory appDocumentsDirectory = await getApplicationDocumentsDirectory();
+    String filePath = '${appDocumentsDirectory.path}/last_data.json';
 
-  // Read file contents
-  File file = File(filePath);
-  if (await file.exists()) {
-    String contents = await file.readAsString();
-    List<dynamic> jsonData = json.decode(contents); // Parse JSON string from file
-    List<Measurement> measurements = jsonData.map((data) => Measurement.fromJson(data)).toList();
-    return FetchResult(measurements, false);
-  } else {
-    throw Exception('File does not exist');
+    // Read file contents
+    File file = File(filePath);
+    if (await file.exists()) {
+      String contents = await file.readAsString();
+      List<dynamic> jsonData = json.decode(contents); // Parse JSON string from file
+      List<Measurement> measurements = jsonData.map((data) => Measurement.fromJson(data)).toList();
+      return FetchResult(measurements, false);
+    } else {
+      throw Exception('File does not exist');
+    }
+  } catch (error) {
+      print('Error in reading measurements from file: $error');
+      return FetchResult([], false);
   }
 }

app/lib/server_requests/fetch_relation.dart

@@ -46,19 +46,24 @@ Future<Uint8List> fetchRelation() async {
 }
 
 Future<Uint8List> loadSavedRelation() async {
-  // Get latest saved relation from file if the server does not respond
-  Directory appDocumentsDirectory = await getApplicationDocumentsDirectory();
-  String filePath = '${appDocumentsDirectory.path}/last_relation.json';
+  try {
+    // Get latest saved relation from file if the server does not respond
+    Directory appDocumentsDirectory = await getApplicationDocumentsDirectory();
+    String filePath = '${appDocumentsDirectory.path}/last_relation.json';
 
-  // Read file contents
-  File file = File(filePath);
-  if (await file.exists()) {
-    String contents = await file.readAsString();
-    List<dynamic> jsonData = json.decode(contents); // Parse JSON string from file
-    Uint8List relation = Uint8List.fromList(utf8.encode(jsonData.toString()));
-    return relation;
-  } else {
-    throw Exception('File does not exist');
+    // Read file contents
+    File file = File(filePath);
+    if (await file.exists()) {
+      String contents = await file.readAsString();
+      List<dynamic> jsonData = json.decode(contents); // Parse JSON string from file
+      Uint8List relation = Uint8List.fromList(utf8.encode(jsonData.toString()));
+      return relation;
+    } else {
+      throw Exception('File does not exist');
+    }
+  } catch (error) {
+      print('Error in reading relation from file: $error');
+      return Uint8List(0);
   }
 }
 

app/lib/server_requests/init_state.dart

@@ -4,6 +4,7 @@ import 'dart:convert';
 import 'dart:typed_data';
 import 'package:app/consts.dart';
 
+import '../consts.dart';
 import '../data_classes.dart';
 import '../server_requests/fetch_markers.dart';
 import '../server_requests/fetch_relation.dart';
@@ -19,30 +20,41 @@ Future<void> initialiseState() async {
   late Future<Uint8List> relationFuture;
 
   try {
-    // Try to fetch measurement data from server
-    markerListFuture = fetchMeasurements().then((fetchResult) {
+
+    // Read data from files if no internet connection
+    if (!internetConnection) {
+      selectedRelation = Uint8List(0); // NB update once fixed
+
+      FetchResult fetchResult = await loadSavedData();
       List<Measurement> measurements = fetchResult.measurements;
-      serverConnection = fetchResult.connected;
-
-      // Return measurements
-      return measurements;
-    }).catchError((error) {
-      serverConnection = false;
-      throw Exception("Failed to fetch measurements: $error");
-    });
-
-    // If measurements were fetched successfully, request relation
-    if (serverConnection) {
-      relationFuture = fetchRelation();
-    } /*else { // Read last saved data
-      relationFuture = loadSavedRelation();
-    }*/
-
-    initSearchOptions();
-
-    //selectedRelation = await relationFuture;
-    selectedRelation = Uint8List(0);
-    selectedMarkerList = await markerListFuture;
+      selectedMarkerList = measurements;
+
+      lakeSearchOptions = ["Mjøsa"];
+    } else { // Try to fetch measurement data from server
+      markerListFuture = fetchMeasurements().then((fetchResult) {
+        List<Measurement> measurements = fetchResult.measurements;
+        serverConnection = fetchResult.connected;
+
+        // Return measurements
+        return measurements;
+      }).catchError((error) {
+        serverConnection = false;
+        throw Exception("Failed to fetch measurements: $error");
+      });
+
+      // If measurements were fetched successfully, request relation
+      if (serverConnection) {
+        relationFuture = fetchRelation();
+      } /*else { // Read last saved data
+        relationFuture = loadSavedRelation();
+      }*/
+
+      initSearchOptions();
+
+      //selectedRelation = await relationFuture;
+      selectedRelation = Uint8List(0); // NB update once fixed
+      selectedMarkerList = await markerListFuture;
+    }
   } catch (e) {
     // Handle any errors that occur during the initialization process
     print("Error during initialization: $e");