Label printing fix (#587)

* Handle blank URL provided for file download

* Improved printing checks

* Auto-select the correct printer

lib/api.dart

@@ -817,6 +817,11 @@ class InvenTreeAPI {
    */
   Future<void> downloadFile(String url, {bool openOnDownload = true}) async {
 
+    if (url.isEmpty) {
+      // No URL provided for download
+      return;
+    }
+
     // Find the local downlods directory
     final Directory dir = await getTemporaryDirectory();
 
@@ -1538,7 +1543,7 @@ class InvenTreeAPI {
       return setting.value;
     }
 
-    final response = await InvenTreeGlobalSetting().getModel(key);
+    final response = await InvenTreeUserSetting().getModel(key);
 
     if (response is InvenTreeUserSetting) {
       response.lastReload = DateTime.now();

lib/inventree/model.dart

@@ -904,7 +904,7 @@ class InvenTreeUserSetting extends InvenTreeGlobalSetting {
 
   @override
   InvenTreeGlobalSetting createFromJson(Map<String, dynamic> json) {
-    return InvenTreeGlobalSetting.fromJson(json);
+    return InvenTreeUserSetting.fromJson(json);
   }
 
   @override

lib/labels.dart

@@ -63,7 +63,11 @@ Future<void> selectAndPrintLabel(
     });
   }
 
-  if (plugin_options.length == 1) {
+  String selectedPlugin = await InvenTreeAPI().getUserSetting("LABEL_DEFAULT_PRINTER");
+
+  if (selectedPlugin.isNotEmpty) {
+    initial_plugin = selectedPlugin;
+  } else if (plugin_options.length == 1) {
     initial_plugin = plugin_options.first["value"];
   }
 
@@ -111,27 +115,29 @@ Future<void> selectAndPrintLabel(
               "items": [instanceId]
             }
           ).then((APIResponse response) {
-            hideLoadingOverlay();
 
             if (response.isValid() && response.statusCode >= 200 &&
                 response.statusCode <= 201) {
               var data = response.asMap();
 
               if (data.containsKey("output")) {
-                var label_file = (data["output"] ?? "") as String;
+                String? label_file = (data["output"]) as String?;
+
+                if (label_file != null && label_file.isNotEmpty) {
+                  // Attempt to open generated file
+                  InvenTreeAPI().downloadFile(label_file);
+                }
 
-                // Attempt to open generated file
-                InvenTreeAPI().downloadFile(label_file);
                 result = true;
               }
             }
         });
-      } else {
+
+        } else {
           // Legacy label printing API
           // Uses a GET request to a specially formed URL which depends on the parameters
           String url = "/label/${labelType}/${labelId}/print/?${labelQuery}&plugin=${pluginKey}";
           await InvenTreeAPI().get(url).then((APIResponse response) {
-            hideLoadingOverlay();
             if (response.isValid() && response.statusCode == 200) {
               var data = response.asMap();
               if (data.containsKey("file")) {
@@ -145,6 +151,8 @@ Future<void> selectAndPrintLabel(
           });
       }
 
+      hideLoadingOverlay();
+
       if (result) {
         showSnackIcon(
           L10().printLabelSuccess,

lib/widget/progress.dart

@@ -66,5 +66,7 @@ void showLoadingOverlay() {
 
 
 void hideLoadingOverlay() {
-  Loader.hide();
+  if (Loader.isShown) {
+    Loader.hide();
+  }
 }