Work on improving async calls

- Still don't fully grok them

lib/api.dart

@@ -55,16 +55,8 @@ class InvenTreeAPI {
 
     print("Connecting to " + address + " -> " + username + ":" + password);
 
-    bool result = false;
+    await _testConnection();
 
-    result = await _testConnection();
-
-    if (!result) {
-      print("Could not connect to server");
-      return;
-    }
-
-    result = await _getToken();
   }
 
   bool _connected = false;
@@ -95,40 +87,34 @@ class InvenTreeAPI {
   }
 
   // Request the raw /api/ endpoint to see if there is an InvenTree server listening
-  Future<bool> _testConnection() async {
+  Future<void> _testConnection() async {
 
     print("Testing connection to server");
 
-    final response = await get("").then((http.Response response) {
+    await get("").then((http.Response response) {
 
       final data = json.decode(response.body);
 
       // We expect certain response from the server
       if (!data.containsKey("server") || !data.containsKey("version")) {
         print("Incorrect keys in server response");
-        return false;
       }
 
       print("Server: " + data["server"]);
       print("Version: " + data["version"]);
 
+      // Ok, server is good. Request token!
+      _getToken();
+
     }).catchError((error) {
       print("Error trying connection");
       print(error);
-
-      return false;
     });
-
-    // Here we have received a response object which is valid
-
-    // TODO - Add timeout handler
-
-    return true;
   }
 
   // Request an API token from the server.
   // A valid username/password combination must be provided
-  Future<bool> _getToken() async {
+  Future<String> _getToken() async {
 
     print("Requesting API token from server");
 
@@ -145,6 +131,7 @@ class InvenTreeAPI {
         });
 
     response.then((http.Response response) {
+
       if (response.statusCode != 200) {
         print("Invalid status code: " + response.statusCode.toString());
         return false;
@@ -153,19 +140,19 @@ class InvenTreeAPI {
 
         if (!data.containsKey("token")) {
           print("No token provided in response");
-          return false;
+          return "";
         }
 
-        // Save the received token
+        // Return the received token
-        _token = data["token"];
+        String token = data["token"];
-        print("Received token: " + _token);
+        print("Received token: " + token);
 
-        return true;
+        return token;
       }
     }).catchError((error) {
       print("Error retrieving token:");
       print(error);
-      return false;
+      return "";
     });
   }
 
@@ -231,11 +218,7 @@ class InvenTreeAPI {
 
     print("GET: " + _url);
 
-    final response = await http.get(_url,
+    return http.get(_url, headers: _headers);
-      headers: _headers,
-    );
-
-    return response;
   }
 
   Map<String, String> _defaultHeaders() {

lib/main.dart

@@ -1,13 +1,35 @@
 import 'package:flutter/material.dart';
-import 'package:preferences/preferences.dart';
+// import 'package:preferences/preferences.dart';
 
 import 'settings.dart';
 import 'api.dart';
 import 'preferences.dart';
+import 'inventree_object.dart';
 
 void main() async {
 
-  await PrefService.init(prefix: "inventree_");
+  // await PrefService.init(prefix: "inventree_");
+
+  String username = "username";
+  String password = "password";
+  String server = "http://127.0.0.1:8000";
+
+  await InvenTreeAPI().connect(server, username, password);
+
+  print("Connected! Requesting data");
+
+  InvenTreePart().list(filters: {"category": "2"}).then((var parts) {
+
+    print("Received list");
+
+    print("Found " + parts.length.toString() + " parts");
+
+    for (var part in parts) {
+      if (part is InvenTreePart) {
+        print("Part: " + part.name + ", " + part.description);
+      }
+    }
+  });
 
   runApp(MyApp());
 }
@@ -69,7 +91,7 @@ class _MyHomePageState extends State<MyHomePage> {
   }
 
   void _login() {
-    Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeSettingsWidget()));
+    //Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeSettingsWidget()));
   }
 
   @override