Adds new custom widget for displaying Bill of Materials data

lib/inventree/bom.dart

@@ -0,0 +1,69 @@
+
+
+import "package:inventree/inventree/model.dart";
+import "package:inventree/inventree/part.dart";
+
+/*
+ * Class representing the BomItem database model
+ */
+class InvenTreeBomItem extends InvenTreeModel {
+
+  InvenTreeBomItem() : super();
+
+  InvenTreeBomItem.fromJson(Map<String, dynamic> json) : super.fromJson(json);
+
+  @override
+  InvenTreeModel createFromJson(Map<String, dynamic> json) {
+    return InvenTreeBomItem.fromJson(json);
+  }
+
+  @override
+  String get URL => "bom/";
+
+  @override
+  Map<String, String> defaultListFilters() {
+    return {
+      "sub_part_detail": "true",
+    };
+  }
+
+  @override
+  Map<String, String> defaultGetFilters() {
+    return {
+      "sub_part_detail": "true",
+    };
+  }
+
+  // Extract the 'quantity' value associated with this BomItem
+  double get quantity => double.tryParse(jsondata["quantity"].toString()) ?? 0;
+
+  // Extract the ID of the related part
+  int get partId => int.tryParse(jsondata["part"].toString()) ?? -1;
+
+  // Return a Part instance for the referenced part
+  InvenTreePart? get part {
+    if (jsondata.containsKey("part_detail")) {
+      dynamic data = jsondata["part_detail"] ?? {};
+      if (data is Map<String, dynamic>) {
+        return InvenTreePart.fromJson(data);
+      }
+    }
+
+    return null;
+  }
+
+  // Return a Part instance for the referenced sub-part
+  InvenTreePart? get subPart {
+    if (jsondata.containsKey("sub_part_detail")) {
+      dynamic data = jsondata["sub_part_detail"] ?? {};
+      if (data is Map<String, dynamic>) {
+        return InvenTreePart.fromJson(data);
+      }
+    }
+
+    return null;
+}
+
+  // Extract the ID of the related sub-part
+  int get subPartId => int.tryParse(jsondata["sub_part"].toString()) ?? -1;
+}