On stock transfer - added merge stock option (already on web UI) (#875)

* added merge stock transfer option

* update release notes and version

lib/barcode/stock.dart

@@ -126,7 +126,7 @@ class StockItemScanIntoLocationHandler extends BarcodeScanStockLocationHandler {
     bool result = false;
 
     if (confirm) {
-      Map<String, dynamic> fields = item.transferFields();
+      Map<String, dynamic> fields = await item.transferFields();
 
       // Override location with scanned value
       fields["location"]?["value"] = locationId;
@@ -243,7 +243,7 @@ class StockLocationScanInItemsHandler extends BarcodeScanStockItemHandler {
         return false;
       } else {
         if (confirm) {
-          Map<String, dynamic> fields = item.transferFields();
+          Map<String, dynamic> fields = await item.transferFields();
 
           // Override location with provided location value
           fields["location"]?["value"] = location.pk;

lib/inventree/stock.dart

@@ -146,13 +146,26 @@ class InvenTreeStockItem extends InvenTreeModel {
   }
 
   // Return a set of fields to transfer this stock item via dialog
-  Map<String, dynamic> transferFields() {
+  Future<Map<String, dynamic>> transferFields() async {
+    // Read the server-side global default for merge-on-transfer
+    final bool mergeDefault = await InvenTreeAPI().getGlobalBooleanSetting(
+      "STOCK_MERGE_ON_TRANSFER",
+    );
+
     Map<String, dynamic> fields = {
       "pk": {"parent": "items", "nested": true, "hidden": true, "value": pk},
       "quantity": {"parent": "items", "nested": true, "value": quantity},
       "location": {"value": locationId},
       "status": {"parent": "items", "nested": true, "value": status},
       "packaging": {"parent": "items", "nested": true, "value": packaging},
+      "merge": {
+        "parent": "items",
+        "nested": true,
+        "type": "boolean",
+        "label": L10().mergeStockOnTransfer,
+        "help_text": L10().mergeStockOnTransferDetail,
+        "value": mergeDefault,
+      },
       "notes": {},
     };
 

lib/l10n/app_en.arb

@@ -1882,6 +1882,12 @@
   "transferStockLocationDetail": "Transfer this stock location into another",
   "@transferStockLocationDetail": {},
 
+  "mergeStockOnTransfer": "Merge stock on transfer",
+  "@mergeStockOnTransfer": {},
+
+  "mergeStockOnTransferDetail": "Merge transferred stock into existing stock at destination if possible",
+  "@mergeStockOnTransferDetail": {},
+
   "translate": "Translate",
   "@translate": {},
 

lib/widget/stock/stock_detail.dart

@@ -459,7 +459,7 @@ class _StockItemDisplayState extends RefreshableState<StockDetailWidget> {
    * Launches an API Form to transfer this stock item to a new location
    */
   Future<void> _transferStockDialog(BuildContext context) async {
-    Map<String, dynamic> fields = widget.item.transferFields();
+    Map<String, dynamic> fields = await widget.item.transferFields();
 
     launchApiForm(
       context,