Catch some subtle errors (#202)

- Prevent API requests for invalid PK values
- Perform checks for invalid PK values at multiple points
- Change order of operations in StockDetail widget

assets/release_notes.md

@@ -7,6 +7,7 @@
 - Allow serial numbers to be specified when creating new stock items
 - Allow serial numbers to be edited for existing stock items
 - Allow app locale to be changed manually
+- Improved handling of certain errors
 
 ### 0.8.1 - August 2022
 ---

lib/inventree/model.dart

@@ -276,6 +276,12 @@ class InvenTreeModel {
   /// Delete the instance on the remote server
   /// Returns true if the operation was successful, else false
   Future<bool> delete() async {
+
+    // Return if we do not have a valid pk
+    if (pk < 0) {
+      return false;
+    }
+
     var response = await api.delete(url);
 
     if (!response.isValid() || response.data == null || (response.data is! Map)) {
@@ -303,18 +309,35 @@ class InvenTreeModel {
    */
   Future<bool> reload() async {
 
+    // If we do not have a valid pk (for some reason), exit immediately
+    if (pk < 0) {
+      return false;
+    }
+
     var response = await api.get(url, params: defaultGetFilters(), expectedStatusCode: 200);
 
-    if (!response.isValid() || response.data == null || (response.data is! Map)) {
+    // A valid response has been returned
+    if (response.isValid() && response.statusCode == 200) {
 
-      reportModelError(
-        "InvenTreeModel.reload() returned invalid response",
-        response,
-        context: {
-          "pk": pk.toString(),
-        }
-      );
+      // Returned data was not a valid JSON object
+      if (response.data == null || response.data is! Map) {
+        reportModelError(
+            "InvenTreeModel.reload() returned invalid response",
+            response,
+            context: {
+              "pk": pk.toString(),
+            }
+        );
 
+        showServerError(
+          url,
+          L10().serverError,
+          L10().responseInvalid,
+        );
+
+        return false;
+      }
+    } else {
       showServerError(
         url,
         L10().serverError,
@@ -322,7 +345,6 @@ class InvenTreeModel {
       );
 
       return false;
-
     }
 
     lastReload = DateTime.now();
@@ -337,6 +359,13 @@ class InvenTreeModel {
 
     var url = path.join(URL, pk.toString());
 
+    // Return if we do not have a valid pk
+    if (pk < 0) {
+      return APIResponse(
+        url: url,
+      );
+    }
+
     if (!url.endsWith("/")) {
       url += "/";
     }
@@ -396,6 +425,11 @@ class InvenTreeModel {
   }
 
   Future<InvenTreeModel?> get(int pk, {Map<String, String> filters = const {}}) async {
+
+    if (pk < 0) {
+      return null;
+    }
+
     return getModel(pk.toString(), filters: filters);
   }
 

lib/widget/stock_detail.dart

@@ -109,13 +109,13 @@ class _StockItemDisplayState extends RefreshableState<StockDetailWidget> {
   @override
   Future<void> request(BuildContext context) async {
 
-    final bool result = await item.reload();
-
     stockShowHistory = await InvenTreeSettingsManager().getValue(INV_STOCK_SHOW_HISTORY, false) as bool;
 
+    final bool result = item.pk > 0 && await item.reload();
+
     // Could not load this stock item for some reason
     // Perhaps it has been depleted?
-    if (!result || item.pk == -1) {
+    if (!result) {
       Navigator.of(context).pop();
     }
 

lib/widget/stock_notes.dart

@@ -31,7 +31,9 @@ class _StockNotesState extends RefreshableState<StockNotesWidget> {
 
   @override
   Future<void> request(BuildContext context) async {
-    await item.reload();
+    if (item.pk > 0) {
+      await item.reload();
+    }
   }
 
   @override