Make a 'refreshable_state' class which makes API requests easier

lib/widget/location_display.dart

@@ -8,10 +8,10 @@ import 'package:flutter/material.dart';
 import 'package:flutter/foundation.dart';
 import 'package:font_awesome_flutter/font_awesome_flutter.dart';
 
+import 'package:InvenTree/widget/refreshable_state.dart';
+
 class LocationDisplayWidget extends StatefulWidget {
 
-
-
   LocationDisplayWidget(this.location, {Key key}) : super(key: key);
 
   final InvenTreeStockLocation location;
@@ -22,21 +22,15 @@ class LocationDisplayWidget extends StatefulWidget {
   _LocationDisplayState createState() => _LocationDisplayState(location);
 }
 
-
-class _LocationDisplayState extends State<LocationDisplayWidget> {
-
-  BuildContext context;
-
-  _LocationDisplayState(this.location) {
-  }
-
-  void initState() {
-    super.initState();
-    WidgetsBinding.instance.addPostFrameCallback((_) => _requestData(context));
-  }
+class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
 
   final InvenTreeStockLocation location;
 
+  @override
+  String app_bar_title = "Stock Location";
+
+  _LocationDisplayState(this.location) {}
+
   List<InvenTreeStockLocation> _sublocations = List<InvenTreeStockLocation>();
 
   String _locationFilter = '';
@@ -52,27 +46,8 @@ class _LocationDisplayState extends State<LocationDisplayWidget> {
 
   List<InvenTreeStockItem> _items = List<InvenTreeStockItem>();
 
-  String get _title {
-
-    if (location == null) {
-      return "Stock Locations";
-    } else {
-      return "Stock Location - ${location.name}";
-    }
-  }
-
-  Future<void> _refresh() async {
-    await _requestData(context);
-  }
-
-  /*
-   * Request data from the server.
-   * It will be displayed once loaded
-   *
-   * - List of sublocations under this one
-   * - List of stock items at this location
-   */
-  Future<void> _requestData(BuildContext context) async {
+  @override
+  Future<void> request(BuildContext context) async {
 
     int pk = location?.pk ?? -1;
 
@@ -146,19 +121,9 @@ class _LocationDisplayState extends State<LocationDisplayWidget> {
   }
 
   @override
-  Widget build(BuildContext context) {
+  Widget getBody(BuildContext context) {
 
-    // Save the context
-    this.context = context;
-
-    return Scaffold(
-      appBar: AppBar(
-        title: Text(_title),
-      ),
-      drawer: new InvenTreeDrawer(context),
-      body: new RefreshIndicator(
-        onRefresh: _refresh,
-        child: ListView(
+    return ListView(
       children: <Widget> [
       locationDescriptionCard(),
       ExpansionPanelList(
@@ -213,8 +178,6 @@ class _LocationDisplayState extends State<LocationDisplayWidget> {
           ]
       ),
     ]
-        )
-      )
     );
   }
 }

lib/widget/refreshable_state.dart

@@ -0,0 +1,61 @@
+import 'package:InvenTree/widget/drawer.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart';
+
+import 'package:InvenTree/widget/drawer.dart';
+
+
+abstract class RefreshableState<T extends StatefulWidget> extends State<T> {
+
+  // Storage for context once "Build" is called
+  BuildContext context;
+
+  String app_bar_title = "App Bar Title";
+
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) => request(context));
+  }
+
+  // Function to request data for this page
+  Future<void> request(BuildContext context) async {
+    return;
+  }
+
+  Future<void> refresh() async {
+    await request(context);
+    setState(() {});
+  }
+
+  // Function to construct an appbar (override if needed)
+  AppBar getAppBar(BuildContext context) {
+    return AppBar(
+      title: Text(app_bar_title)
+    );
+  }
+
+  // Function to construct a drawer (override if needed)
+  Widget getDrawer(BuildContext context) {
+    return InvenTreeDrawer(context);
+  }
+
+  // Function to construct a body (MUST BE PROVIDED)
+  Widget getBody(BuildContext context);
+
+  @override
+  Widget build(BuildContext context) {
+
+    // Save the context for future use
+    this.context = context;
+
+    return Scaffold(
+      appBar: getAppBar(context),
+      drawer: getDrawer(context),
+      body: RefreshIndicator(
+        onRefresh: refresh,
+        child: getBody(context)
+      )
+    );
+  }
+}