Top level fix (#874)

* Fix top-level items

* Show pagination error messages

* Update release notes

* Check API version

lib/api.dart

@@ -308,6 +308,9 @@ class InvenTreeAPI {
 
   bool get supportsUserPermissions => apiVersion >= 207;
 
+  // Ref: https://github.com/inventree/InvenTree/pull/7514
+  bool get supportsTopLevelFiltering => apiVersion >= 209;
+
   // Does the server support the "destination" field on the PurchaseOrder model?
   // Ref: https://github.com/inventree/InvenTree/pull/8403
   bool get supportsPurchaseOrderDestination => apiVersion >= 276;

lib/inventree/model.dart

@@ -752,6 +752,12 @@ class InvenTreeModel {
       return null;
     }
 
+    // A client error (e.g. 400 Bad Request) was returned - notify the user
+    if (response.clientError()) {
+      showStatusCodeError(URL, response.statusCode, details: response.data);
+      return null;
+    }
+
     // Construct the response
     InvenTreePageResponse page = InvenTreePageResponse();
 

lib/widget/part/category_display.dart

@@ -1,6 +1,7 @@
 import "package:flutter/material.dart";
 import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:flutter_tabler_icons/flutter_tabler_icons.dart";
+import "package:inventree/api.dart";
 
 import "package:inventree/app_colors.dart";
 import "package:inventree/l10.dart";
@@ -193,7 +194,11 @@ class _CategoryDisplayState extends RefreshableState<CategoryDisplayWidget> {
     if (parent != null) {
       filters["parent"] = parent.toString();
     } else {
-      filters["parent"] = "null";
+      if (InvenTreeAPI().supportsTopLevelFiltering) {
+        filters["top_level"] = "true";
+      } else {
+        filters["parent"] = "null";
+      }
     }
 
     List<Widget> tiles = <Widget>[

lib/widget/stock/location_display.dart

@@ -1,6 +1,7 @@
 import "package:flutter/material.dart";
 import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:flutter_tabler_icons/flutter_tabler_icons.dart";
+import "package:inventree/api.dart";
 
 import "package:inventree/app_colors.dart";
 import "package:inventree/barcode/barcode.dart";
@@ -361,7 +362,11 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
     if (parent != null) {
       filters["parent"] = parent.toString();
     } else {
-      filters["parent"] = "null";
+      if (InvenTreeAPI().supportsTopLevelFiltering) {
+        filters["top_level"] = "true";
+      } else {
+        filters["parent"] = "null";
+      }
     }
 
     List<Widget> tiles = [