Project code support (#336)

* Determine if project codes are supported

* Add helpers for boolean functions

* Adds helper methods for generic "model" class

- Will allow us to do some good refactoring

* Refactor the refactor

* Add debug support and getMap function

* Major refactoring for model data accessors

* Handle null values

* Add sentry reporting if key is used incorrectly

* Fix typo

* Refactor createFromJson function

* Add model for ProjectCode

* Display and edit project code for purchase orders

lib/api.dart

@@ -300,6 +300,9 @@ class InvenTreeAPI {
   // Order barcodes API v107 or newer
   bool get supportsOrderBarcodes => isConnected() && apiVersion >= 107;
 
+  // Project codes require v109 or newer
+  bool get supportsProjectCodes => isConnected() && apiVersion >= 109;
+
   // Are plugins enabled on the server?
   bool _pluginsEnabled = false;
 
@@ -1362,6 +1365,12 @@ class InvenTreeAPI {
     }
   }
 
+  // Return a boolean global setting value
+  Future<bool> getGlobalBooleanSetting(String key) async {
+    String value = await getGlobalSetting(key);
+    return value.toLowerCase() == "true";
+  }
+
   Future<String> getUserSetting(String key) async {
     if (!supportsSettings) return "";
 
@@ -1382,6 +1391,12 @@ class InvenTreeAPI {
     }
   }
 
+  // Return a boolean user setting value
+  Future<bool> getUserBooleanSetting(String key) async {
+    String value = await getUserSetting(key);
+    return value.toLowerCase() == "true";
+  }
+
   /*
    * Send a request to the server to locate / identify either a StockItem or StockLocation
    */

lib/api_form.dart

@@ -15,6 +15,7 @@ import "package:inventree/l10.dart";
 
 import "package:inventree/inventree/company.dart";
 import "package:inventree/inventree/part.dart";
+import "package:inventree/inventree/project_code.dart";
 import "package:inventree/inventree/sentry.dart";
 import "package:inventree/inventree/stock.dart";
 
@@ -667,6 +668,13 @@ class APIFormField {
             height: 40
           )
         );
+      case "projectcode":
+        var project_code = InvenTreeProjectCode.fromJson(data);
+        return ListTile(
+          title: Text(project_code.code),
+          subtitle: Text(project_code.description),
+          leading: FaIcon(FontAwesomeIcons.list)
+        );
       default:
         return ListTile(
           title: Text(

lib/inventree/bom.dart

@@ -12,9 +12,7 @@ class InvenTreeBomItem extends InvenTreeModel {
   InvenTreeBomItem.fromJson(Map<String, dynamic> json) : super.fromJson(json);
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreeBomItem.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeBomItem.fromJson(json);
 
   @override
   String get URL => "bom/";
@@ -36,13 +34,13 @@ class InvenTreeBomItem extends InvenTreeModel {
   }
 
   // Extract the 'reference' value associated with this BomItem
-  String get reference => (jsondata["reference"] ?? "") as String;
-
+  String get reference => getString("reference");
+  
   // Extract the 'quantity' value associated with this BomItem
-  double get quantity => double.tryParse(jsondata["quantity"].toString()) ?? 0;
+  double get quantity => getDouble("quantity");
 
   // Extract the ID of the related part
-  int get partId => int.tryParse(jsondata["part"].toString()) ?? -1;
+  int get partId => getInt("part");
 
   // Return a Part instance for the referenced part
   InvenTreePart? get part {
@@ -69,5 +67,5 @@ class InvenTreeBomItem extends InvenTreeModel {
 }
 
   // Extract the ID of the related sub-part
-  int get subPartId => int.tryParse(jsondata["sub_part"].toString()) ?? -1;
+  int get subPartId => getInt("sub_part");
 }

lib/inventree/company.dart

@@ -38,22 +38,22 @@ class InvenTreeCompany extends InvenTreeModel {
 
   String get thumbnail => (jsondata["thumbnail"] ?? jsondata["image"] ?? InvenTreeAPI.staticThumb) as String;
 
-  String get website => (jsondata["website"] ?? "") as String;
+  String get website => getString("website");
+  
+  String get phone => getString("phone");
 
-  String get phone => (jsondata["phone"] ?? "") as String;
+  String get email => getString("email");
 
-  String get email => (jsondata["email"] ?? "") as String;
+  bool get isSupplier => getBool("is_supplier");
 
-  bool get isSupplier => (jsondata["is_supplier"] ?? false) as bool;
+  bool get isManufacturer => getBool("is_manufacturer");
 
-  bool get isManufacturer => (jsondata["is_manufacturer"] ?? false)  as bool;
-
-  bool get isCustomer => (jsondata["is_customer"] ?? false) as bool;
-
-  int get partSuppliedCount => (jsondata["parts_supplied"] ?? 0) as int;
-
-  int get partManufacturedCount => (jsondata["parts_manufactured"] ?? 0) as int;
+  bool get isCustomer => getBool("is_customer");
 
+  int get partSuppliedCount => getInt("part_supplied");
+  
+  int get partManufacturedCount => getInt("parts_manufactured");
+  
   // Request a list of purchase orders against this company
   Future<List<InvenTreePurchaseOrder>> getPurchaseOrders({bool? outstanding}) async {
 
@@ -81,11 +81,7 @@ class InvenTreeCompany extends InvenTreeModel {
   }
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    var company = InvenTreeCompany.fromJson(json);
-
-    return company;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeCompany.fromJson(json);
 }
 
 
@@ -154,40 +150,36 @@ class InvenTreeSupplierPart extends InvenTreeModel {
     return _filters();
   }
 
-  int get manufacturerId => (jsondata["manufacturer_detail"]["pk"] ?? -1) as int;
-
-  String get manufacturerName => (jsondata["manufacturer_detail"]?["name"] ?? "") as String;
-
-  String get MPN => (jsondata["manufacturer_part_detail"]?["MPN"] ?? "") as String;
-
+  int get manufacturerId => getInt("pk", subKey: "manufacturer_detail");
+  
+  String get manufacturerName => getString("name", subKey: "manufacturer_detail");
+  
+  String get MPN => getString("MPN", subKey: "manufacturer_part_detail");
+  
   String get manufacturerImage => (jsondata["manufacturer_detail"]?["image"] ?? jsondata["manufacturer_detail"]["thumbnail"] ?? InvenTreeAPI.staticThumb) as String;
 
-  int get manufacturerPartId => (jsondata["manufacturer_part"] ?? -1) as int;
-
-  int get supplierId => (jsondata["supplier"] ?? -1) as int;
-
-  String get supplierName => (jsondata["supplier_detail"]?["name"] ?? "") as String;
-
+  int get manufacturerPartId => getInt("manufacturer_part");
+  
+  int get supplierId => getInt("supplier");
+  
+  String get supplierName => getString("name", subKey: "supplier_detail");
+  
   String get supplierImage => (jsondata["supplier_detail"]?["image"] ?? jsondata["supplier_detail"]["thumbnail"] ?? InvenTreeAPI.staticThumb) as String;
 
-  String get SKU => (jsondata["SKU"] ?? "") as String;
-
-  int get partId => (jsondata["part"] ?? -1) as int;
-
+  String get SKU => getString("SKU");
+  
+  int get partId => getInt("part");
+  
   String get partImage => (jsondata["part_detail"]?["thumbnail"] ?? InvenTreeAPI.staticThumb) as String;
 
-  String get partName => (jsondata["part_detail"]?["full_name"] ?? "") as String;
-
-  String get partDescription => (jsondata["part_detail"]?["description"] ?? "") as String;
-
-  String get note => (jsondata["note"] ?? "") as String;
+  String get partName => getString("full_name", subKey: "part_detail");
+  
+  String get partDescription => getString("description", subKey: "part_detail");
+  
+  String get note => getString("note");
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    var part = InvenTreeSupplierPart.fromJson(json);
-
-    return part;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeSupplierPart.fromJson(json);
 }
 
 
@@ -207,16 +199,12 @@ class InvenTreeManufacturerPart extends InvenTreeModel {
     };
   }
 
-  int get partId => (jsondata["part"] ?? -1) as int;
-
-  int get manufacturerId => (jsondata["manufacturer"] ?? -1) as int;
-
-  String get MPN => (jsondata["MPN"] ?? "") as String;
-
+  int get partId => getInt("part");
+  
+  int get manufacturerId => getInt("manufacturer");
+  
+  String get MPN => getString("MPN");
+  
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    var part = InvenTreeManufacturerPart.fromJson(json);
-
-    return part;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeManufacturerPart.fromJson(json);
 }

lib/inventree/model.dart

@@ -63,6 +63,96 @@ class InvenTreeModel {
   // Note: If the WEB_URL is the same (except for /api/) as URL then just leave blank
   String get WEB_URL => "";
 
+  // Helper function to set a value in the JSON data
+  void setValue(String key, dynamic value) {
+    jsondata[key] = value;
+  }
+
+  // return a dynamic value from the JSON data
+  // optionally we can specifiy a "subKey" to get a value from a sub-dictionary
+  dynamic getValue(String key, {dynamic backup, String subKey = ""}) {
+    Map<String, dynamic> data = jsondata;
+
+    // If a subKey is specified, we need to dig deeper into the JSON data
+    if (subKey.isNotEmpty) {
+
+      if (!data.containsKey(subKey)) {
+        debug("JSON data does not contain subKey '$subKey' for key '$key'");
+        return backup;
+      }
+
+      dynamic sub_data = data[subKey];
+
+      if (sub_data is Map<String, dynamic>) {
+        data = (data[subKey] ?? {}) as Map<String, dynamic>;
+      }
+
+    }
+
+    if (data.containsKey(key)) {
+      return data[key];
+    } else {
+      debug("JSON data does not contain key '$key' (subKey '${subKey}')");
+      return backup;
+    }
+  }
+
+  // Helper function to get sub-map from JSON data
+  Map<String, dynamic> getMap(String key, {Map<String, dynamic> backup = const {}, String subKey = ""}) {
+    dynamic value = getValue(key, backup: backup, subKey: subKey);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return value as Map<String, dynamic>;
+  }
+
+  // Helper function to get string value from JSON data
+  String getString(String key, {String backup = "", String subKey = ""}) {
+    dynamic value = getValue(key, backup: backup, subKey: subKey);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return value.toString();
+  }
+
+  // Helper function to get integer value from JSON data
+  int getInt(String key, {int backup = -1, String subKey = ""}) {
+    dynamic value = getValue(key, backup: backup, subKey: subKey);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return int.tryParse(value.toString()) ?? backup;
+  }
+
+  // Helper function to get double value from JSON data
+  double getDouble(String key, {double backup = 0.0, String subKey = ""}) {
+    dynamic value = getValue(key, backup: backup, subKey: subKey);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return double.tryParse(value.toString()) ?? backup;
+  }
+
+  // Helper function to get boolean value from json data
+  bool getBool(String key, {bool backup = false, String subKey = ""}) {
+    dynamic value = getValue(key, backup: backup, subKey: subKey);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return value.toString().toLowerCase() == "true";
+  }
+
+  // Return the InvenTree web server URL for this object
   String get webUrl {
 
     if (api.isConnected()) {
@@ -191,16 +281,16 @@ class InvenTreeModel {
   // Accessor for the API
   InvenTreeAPI get api => InvenTreeAPI();
 
-  int get pk => (jsondata["pk"] ?? -1) as int;
-
+  int get pk => getInt("pk");
+  
   // Some common accessors
-  String get name => (jsondata["name"] ?? "") as String;
+  String get name => getString("name");
 
-  String get description => (jsondata["description"] ?? "") as String;
+  String get description => getString("description");
+  
+  String get notes => getString("notes");
 
-  String get notes => (jsondata["notes"] ?? "") as String;
-
-  int get parentId => (jsondata["parent"] ?? -1) as int;
+  int get parentId => getInt("parent");
 
   // Legacy API provided external link as "URL", while newer API uses "link"
   String get link => (jsondata["link"] ?? jsondata["URL"] ?? "") as String;
@@ -297,15 +387,10 @@ class InvenTreeModel {
     }
   }
 
-  String get keywords => (jsondata["keywords"] ?? "") as String;
-
+  String get keywords => getString("keywords");
+  
   // Create a new object from JSON data (not a constructor!)
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-
-      var obj = InvenTreeModel.fromJson(json);
-
-      return obj;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeModel.fromJson(json);
 
   // Return the API detail endpoint for this Model object
   String get url => "${URL}/${pk}/".replaceAll("//", "/");
@@ -746,9 +831,7 @@ class InvenTreePlugin extends InvenTreeModel {
   InvenTreePlugin.fromJson(Map<String, dynamic> json) : super.fromJson(json);
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePlugin.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePlugin.fromJson(json);
 
   @override
   String get URL {
@@ -765,10 +848,10 @@ class InvenTreePlugin extends InvenTreeModel {
     }
   }
 
-  String get key => (jsondata["key"] ?? "") as String;
-
-  bool get active => (jsondata["active"] ?? false) as bool;
-
+  String get key => getString("key");
+  
+  bool get active => getBool("active");
+  
   // Return the metadata struct for this plugin
   Map<String, dynamic> get _meta => (jsondata["meta"] ?? {}) as Map<String, dynamic>;
 
@@ -803,11 +886,11 @@ class InvenTreeGlobalSetting extends InvenTreeModel {
   @override
   String get URL => "settings/global/";
 
-  String get key => (jsondata["key"] ?? "") as String;
-
-  String get value => (jsondata["value"] ?? "") as String;
-
-  String get type => (jsondata["type"] ?? "") as String;
+  String get key => getString("key");
+  
+  String get value => getString("value");
+  
+  String get type => getString("type");
 
 }
 
@@ -836,8 +919,8 @@ class InvenTreeAttachment extends InvenTreeModel {
   // Override this reference field for any subclasses
   String get REFERENCE_FIELD => "";
 
-  String get attachment => (jsondata["attachment"] ?? "") as String;
-
+  String get attachment => getString("attachment");
+  
   // Return the filename of the attachment
   String get filename {
     return attachment.split("/").last;
@@ -874,8 +957,8 @@ class InvenTreeAttachment extends InvenTreeModel {
     return FontAwesomeIcons.fileLines;
   }
 
-  String get comment => (jsondata["comment"] ?? "") as String;
-
+  String get comment => getString("comment");
+  
   DateTime? get uploadDate {
     if (jsondata.containsKey("upload_date")) {
       return DateTime.tryParse((jsondata["upload_date"] ?? "") as String);

lib/inventree/notification.dart

@@ -27,8 +27,8 @@ class InvenTreeNotification extends InvenTreeModel {
     };
   }
 
-  String get message => (jsondata["message"] ?? "") as String;
-
+  String get message => getString("message");
+  
   DateTime? get creationDate {
     if (jsondata.containsKey("creation")) {
       return DateTime.tryParse((jsondata["creation"] ?? "") as String);

lib/inventree/part.dart

@@ -43,8 +43,8 @@ class InvenTreePartCategory extends InvenTreeModel {
     return fields;
   }
 
-  String get pathstring => (jsondata["pathstring"] ?? "") as String;
-
+  String get pathstring => getString("pathstring");
+  
   String get parentPathString {
 
     List<String> psplit = pathstring.split("/");
@@ -67,11 +67,7 @@ class InvenTreePartCategory extends InvenTreeModel {
   int get partcount => (jsondata["part_count"] ?? jsondata["parts"] ?? 0) as int;
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    var cat = InvenTreePartCategory.fromJson(json);
-
-    return cat;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePartCategory.fromJson(json);
 }
 
 
@@ -87,22 +83,18 @@ class InvenTreePartTestTemplate extends InvenTreeModel {
   @override
   String get URL => "part/test-template/";
 
-  String get key => (jsondata["key"] ?? "") as String;
+  String get key => getString("key");
 
-  String get testName => (jsondata["test_name"] ?? "") as String;
+  String get testName => getString("test_name");
 
-  bool get required => (jsondata["required"] ?? false) as bool;
+  bool get required => getBool("required");
+  
+  bool get requiresValue => getBool("requires_value");
 
-  bool get requiresValue => (jsondata["requires_value"] ?? false) as bool;
-
-  bool get requiresAttachment => (jsondata["requires_attachment"] ?? false) as bool;
+  bool get requiresAttachment => getBool("requires_attachment");
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    var template = InvenTreePartTestTemplate.fromJson(json);
-
-    return template;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePartTestTemplate.fromJson(json);
 
   bool passFailStatus() {
 
@@ -142,9 +134,7 @@ class InvenTreePartParameter extends InvenTreeModel {
   String get URL => "part/parameter/";
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePartParameter.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePartParameter.fromJson(json);
 
   @override
   Map<String, dynamic> formFields() {
@@ -152,13 +142,13 @@ class InvenTreePartParameter extends InvenTreeModel {
   }
 
   @override
-  String get name => (jsondata["template_detail"]?["name"] ?? "") as String;
+  String get name => getString("name", subKey: "template_detail");
 
   @override
-  String get description => (jsondata["template_detail"]?["description"] ?? "") as String;
-
-  String get value => jsondata["data"] as String;
-
+  String get description => getString("description", subKey: "template_detail");
+  
+  String get value => getString("data");
+  
   String get valueString {
     String v = value;
 
@@ -170,7 +160,7 @@ class InvenTreePartParameter extends InvenTreeModel {
     return v;
   }
 
-  String get units => (jsondata["template_detail"]?["units"] ?? "") as String;
+  String get units => getString("units", subKey: "template_detail");
 }
 
 /*
@@ -254,8 +244,8 @@ class InvenTreePart extends InvenTreeModel {
     });
   }
 
-  int get supplierCount => (jsondata["suppliers"] ?? 0) as int;
-
+  int get supplierCount => getInt("suppliers", backup: 0);
+  
   // Request supplier parts for this part
   Future<List<InvenTreeSupplierPart>> getSupplierParts() async {
     List<InvenTreeSupplierPart> _supplierParts = [];
@@ -301,40 +291,26 @@ class InvenTreePart extends InvenTreeModel {
 
   int? get defaultLocation => jsondata["default_location"] as int?;
 
-    // Get the number of stock on order for this Part
-    double get onOrder => double.tryParse(jsondata["ordering"].toString()) ?? 0;
+  double get onOrder => getDouble("ordering");
 
-    String get onOrderString {
+  String get onOrderString => simpleNumberString(onOrder);
 
-      return simpleNumberString(onOrder);
+  double get inStock => getDouble("in_stock");
+
+  String get inStockString => simpleNumberString(inStock);
+
+  // Get the 'available stock' for this Part
+  double get unallocatedStock {
+
+    // Note that the 'available_stock' was not added until API v35
+    if (jsondata.containsKey("unallocated_stock")) {
+      return double.tryParse(jsondata["unallocated_stock"].toString()) ?? 0;
+    } else {
+      return inStock;
     }
+  }
 
-    // Get the stock count for this Part
-    double get inStock => double.tryParse(jsondata["in_stock"].toString()) ?? 0;
-
-    String get inStockString {
-
-      String q = simpleNumberString(inStock);
-
-      return q;
-    }
-
-    // Get the 'available stock' for this Part
-    double get unallocatedStock {
-
-      // Note that the 'available_stock' was not added until API v35
-      if (jsondata.containsKey("unallocated_stock")) {
-        return double.tryParse(jsondata["unallocated_stock"].toString()) ?? 0;
-      } else {
-        return inStock;
-      }
-    }
-
-    String get unallocatedStockString {
-      String q = simpleNumberString(unallocatedStock);
-
-      return q;
-    }
+    String get unallocatedStockString => simpleNumberString(unallocatedStock);
 
     String stockString({bool includeUnits = true}) {
       String q = unallocatedStockString;
@@ -350,39 +326,39 @@ class InvenTreePart extends InvenTreeModel {
       return q;
     }
 
-    String get units => (jsondata["units"] ?? "") as String;
+    String get units => getString("units");
 
     // Get the ID of the Part that this part is a variant of (or null)
     int? get variantOf => jsondata["variant_of"] as int?;
 
     // Get the number of units being build for this Part
-    double get building => double.tryParse(jsondata["building"].toString()) ?? 0;
+    double get building => getDouble("building");
 
     // Get the number of BOMs this Part is used in (if it is a component)
-    int get usedInCount => (jsondata["used_in"] ?? 0) as int;
+    int get usedInCount => jsondata.containsKey("used_in") ? getInt("used_in", backup: 0) : 0;
 
-    bool get isAssembly => (jsondata["assembly"] ?? false) as bool;
+    bool get isAssembly => getBool("assembly");
 
-    bool get isComponent => (jsondata["component"] ?? false) as bool;
+    bool get isComponent => getBool("component");
 
-    bool get isPurchaseable => (jsondata["purchaseable"] ?? false) as bool;
+    bool get isPurchaseable => getBool("purchaseable");
 
-    bool get isSalable => (jsondata["salable"] ?? false) as bool;
+    bool get isSalable => getBool("salable");
 
-    bool get isActive => (jsondata["active"] ?? false) as bool;
+    bool get isActive => getBool("active");
 
-    bool get isVirtual => (jsondata["virtual"] ?? false) as bool;
+    bool get isVirtual => getBool("virtual");
 
-    bool get isTrackable => (jsondata["trackable"] ?? false) as bool;
+    bool get isTrackable => getBool("trackable");
 
     // Get the IPN (internal part number) for the Part instance
-    String get IPN => (jsondata["IPN"] ?? "") as String;
+    String get IPN => getString("IPN");
 
     // Get the revision string for the Part instance
-    String get revision => (jsondata["revision"] ?? "") as String;
+    String get revision => getString("revision");
 
     // Get the category ID for the Part instance (or "null" if does not exist)
-    int get categoryId => (jsondata["category"] ?? -1) as int;
+    int get categoryId => getInt("category");
 
     // Get the category name for the Part instance
     String get categoryName {
@@ -404,15 +380,15 @@ class InvenTreePart extends InvenTreeModel {
       return (jsondata["category_detail"]?["description"] ?? "") as String;
     }
     // Get the image URL for the Part instance
-    String get _image  => (jsondata["image"] ?? "") as String;
+    String get _image  => getString("image");
 
     // Get the thumbnail URL for the Part instance
-    String get _thumbnail => (jsondata["thumbnail"] ?? "") as String;
+    String get _thumbnail => getString("thumbnail");
 
     // Return the fully-qualified name for the Part instance
     String get fullname {
 
-      String fn = (jsondata["full_name"] ?? "") as String;
+      String fn = getString("full_name");
 
       if (fn.isNotEmpty) return fn;
 
@@ -456,15 +432,10 @@ class InvenTreePart extends InvenTreeModel {
     }
 
     // Return the "starred" status of this part
-    bool get starred => (jsondata["starred"] ?? false) as bool;
+    bool get starred => getBool("starred");
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-
-    var part = InvenTreePart.fromJson(json);
-
-    return part;
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePart.fromJson(json);
 }
 
 /*
@@ -483,8 +454,6 @@ class InvenTreePartAttachment extends InvenTreeAttachment {
   String get URL => "part/attachment/";
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePartAttachment.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePartAttachment.fromJson(json);
 
 }

lib/inventree/project_code.dart

@@ -0,0 +1,28 @@
+import "package:inventree/inventree/model.dart";
+
+
+/*
+ * Class representing the ProjectCode database model
+ */
+class InvenTreeProjectCode extends InvenTreeModel {
+
+  InvenTreeProjectCode() : super();
+
+  InvenTreeProjectCode.fromJson(Map<String, dynamic> json) : super.fromJson(json);
+
+  @override
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeProjectCode.fromJson(json);
+
+  @override
+  String get URL => "project-code/";
+
+  @override
+  Map<String, dynamic> formFields() {
+    return {
+      "code": {},
+      "description": {},
+    };
+  }
+
+  String get code => getString("code");
+}

lib/inventree/purchase_order.dart

@@ -34,6 +34,7 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
       },
       "supplier_reference": {},
       "description": {},
+      "project_code": {},
       "target_date": {},
       "link": {},
       "responsible": {},
@@ -59,23 +60,32 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
     };
   }
 
-  String get issueDate => (jsondata["issue_date"] ?? "") as String;
+  String get issueDate => getString("issue_date");
 
-  String get completeDate => (jsondata["complete_date"] ?? "") as String;
+  String get completeDate => getString("complete_date");
 
-  String get creationDate => (jsondata["creation_date"] ?? "") as String;
+  String get creationDate => getString("creation_date");
 
-  String get targetDate => (jsondata["target_date"] ?? "") as String;
+  String get targetDate => getString("target_date");
 
-  int get lineItemCount => (jsondata["line_items"] ?? 0) as int;
+  int get lineItemCount => getInt("line_items", backup: 0);
+  
+  bool get overdue => getBool("overdue");
 
-  bool get overdue => (jsondata["overdue"] ?? false) as bool;
+  String get reference => getString("reference");
 
-  String get reference => (jsondata["reference"] ?? "") as String;
+  int get responsibleId => getInt("responsible");
 
-  int get responsibleId => (jsondata["responsible"] ?? -1) as int;
+  int get supplierId => getInt("supplier");
 
-  int get supplierId => (jsondata["supplier"] ?? -1) as int;
+  // Project code information
+  int get projectCodeId => getInt("project_code");
+
+  String get projectCode => getString("code", subKey: "project_code_detail");
+
+  String get projectCodeDescription => getString("description", subKey: "project_code_detail");
+
+  bool get hasProjectCode => projectCode.isNotEmpty;
 
   InvenTreeCompany? get supplier {
 
@@ -88,11 +98,11 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
     }
   }
 
-  String get supplierReference => (jsondata["supplier_reference"] ?? "") as String;
+  String get supplierReference => getString("supplier_reference");
 
-  int get status => (jsondata["status"] ?? -1) as int;
+  int get status => getInt("status");
 
-  String get statusText => (jsondata["status_text"] ?? "") as String;
+  String get statusText => getString("status_text");
 
   bool get isOpen => status == PO_STATUS_PENDING || status == PO_STATUS_PLACED;
 
@@ -103,7 +113,7 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
   bool get isFailed => status == PO_STATUS_CANCELLED || status == PO_STATUS_LOST || status == PO_STATUS_RETURNED;
 
   double? get totalPrice {
-    String price = (jsondata["total_price"] ?? "") as String;
+    String price = getString("total_price");
 
     if (price.isEmpty) {
       return null;
@@ -112,7 +122,7 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
     }
   }
 
-  String get totalPriceCurrency => (jsondata["total_price_currency"] ?? "") as String;
+  String get totalPriceCurrency => getString("total_price_currency");
 
   Future<List<InvenTreePOLineItem>> getLineItems() async {
 
@@ -134,9 +144,7 @@ class InvenTreePurchaseOrder extends InvenTreeModel {
   }
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePurchaseOrder.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePurchaseOrder.fromJson(json);
 
   /// Mark this order as "placed" / "issued"
   Future<void> issueOrder() async {
@@ -199,17 +207,17 @@ class InvenTreePOLineItem extends InvenTreeModel {
 
   bool get isComplete => received >= quantity;
 
-  double get quantity => (jsondata["quantity"] ?? 0) as double;
+  double get quantity => getDouble("quantity");
 
-  double get received => (jsondata["received"] ?? 0) as double;
+  double get received => getDouble("received");
 
   double get outstanding => quantity - received;
 
-  String get reference => (jsondata["reference"] ?? "") as String;
+  String get reference => getString("reference");
 
-  int get orderId => (jsondata["order"] ?? -1) as int;
+  int get orderId => getInt("order");
 
-  int get supplierPartId => (jsondata["part"] ?? -1) as int;
+  int get supplierPartId => getInt("part");
 
   InvenTreePart? get part {
     dynamic part_detail = jsondata["part_detail"];
@@ -232,20 +240,19 @@ class InvenTreePOLineItem extends InvenTreeModel {
     }
   }
 
-  double get purchasePrice => double.parse((jsondata["purchase_price"] ?? "") as String);
+  double get purchasePrice => getDouble("purchase_price");
+  
+  String get purchasePriceCurrency => getString("purchase_price_currency");
 
-  String get purchasePriceCurrency => (jsondata["purchase_price_currency"] ?? "") as String;
+  String get purchasePriceString => getString("purchase_price_string");
 
-  String get purchasePriceString => (jsondata["purchase_price_string"] ?? "") as String;
-
-  int get destination => (jsondata["destination"] ?? -1) as int;
-
-  Map<String, dynamic> get destinationDetail => (jsondata["destination_detail"] ?? {}) as Map<String, dynamic>;
+  int get destination => getInt("destination");
 
+  Map<String, dynamic> get destinationDetail => getMap("destination_detail");
+  
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePOLineItem.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePOLineItem.fromJson(json);
+
 }
 
 /*
@@ -264,7 +271,6 @@ class InvenTreePurchaseOrderAttachment extends InvenTreeAttachment {
   String get URL => "order/po/attachment/";
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreePurchaseOrderAttachment.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreePurchaseOrderAttachment.fromJson(json);
+
 }

lib/inventree/stock.dart

@@ -35,18 +35,18 @@ class InvenTreeStockItemTestResult extends InvenTreeModel {
     };
   }
 
-  String get key => (jsondata["key"] ?? "") as String;
-
-  String get testName => (jsondata["test"] ?? "") as String;
-
-  bool get result => (jsondata["result"] ?? false) as bool;
-
-  String get value => (jsondata["value"] ?? "") as String;
-
-  String get attachment => (jsondata["attachment"] ?? "") as String;
-
-  String get date => (jsondata["date"] ?? "") as String;
+  String get key => getString("key");
+  
+  String get testName => getString("test");
 
+  bool get result => getBool("result");
+  
+  String get value => getString("value");
+  
+  String get attachment => getString("attachment");
+  
+  String get date => getString("date");
+  
   @override
   InvenTreeStockItemTestResult createFromJson(Map<String, dynamic> json) {
     var result = InvenTreeStockItemTestResult.fromJson(json);
@@ -63,9 +63,7 @@ class InvenTreeStockItemHistory extends InvenTreeModel {
   InvenTreeStockItemHistory.fromJson(Map<String, dynamic> json) : super.fromJson(json);
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreeStockItemHistory.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeStockItemHistory.fromJson(json);
 
   @override
   String get URL => "stock/track/";
@@ -98,16 +96,10 @@ class InvenTreeStockItemHistory extends InvenTreeModel {
     return DateFormat("yyyy-MM-dd").format(d);
   }
 
-  String get label => (jsondata["label"] ?? "") as String;
-
+  String get label => getString("label");
+  
   // Return the "deltas" associated with this historical object
-  Map<String, dynamic> get deltas {
-    if (jsondata.containsKey("deltas")) {
-      return jsondata["deltas"] as Map<String, dynamic>;
-    } else {
-      return {};
-    }
-  }
+  Map<String, dynamic> get deltas => getMap("deltas");
 
   // Return the quantity string for this historical object
   String get quantityString {
@@ -122,12 +114,13 @@ class InvenTreeStockItemHistory extends InvenTreeModel {
     }
   }
 
-  String get userString {
-    return (jsondata["user_detail"]?["username"] ?? "") as String;
-  }
+  String get userString => getString("username", subKey: "user_detail");
 }
 
 
+/*
+ * Class representing a StockItem database instance
+ */
 class InvenTreeStockItem extends InvenTreeModel {
 
   InvenTreeStockItem() : super();
@@ -237,16 +230,16 @@ class InvenTreeStockItem extends InvenTreeModel {
     });
   }
 
-  int get status => (jsondata["status"] ?? -1) as int;
+  int get status => getInt("status");
+  
+  String get packaging => getString("packaging");
 
-  String get packaging => (jsondata["packaging"] ?? "") as String;
+  String get batch => getString("batch");
 
-  String get batch => (jsondata["batch"] ?? "") as String;
-
-  int get partId => (jsondata["part"] ?? -1) as int;
+  int get partId => getInt("part");
   
   double? get purchasePrice {
-    String pp = (jsondata["purchase_price"] ?? "") as String;
+    String pp = getString("purchase_price");
 
     if (pp.isEmpty) {
       return null;
@@ -255,18 +248,18 @@ class InvenTreeStockItem extends InvenTreeModel {
     }
   }
 
-  String get purchasePriceCurrency => (jsondata["purchase_price_currency"] ?? "") as String;
+  String get purchasePriceCurrency => getString("purchase_price_currency");
 
   bool get hasPurchasePrice {
     double? pp = purchasePrice;
     return pp != null && pp > 0;
   }
 
-  int get purchaseOrderId => (jsondata["purchase_order"] ?? -1) as int;
+  int get purchaseOrderId => getInt("purchase_order");
 
-  int get trackingItemCount => (jsondata["tracking_items"] ?? 0) as int;
-
-  bool get isBuilding => (jsondata["is_building"] ?? false) as bool;
+  int get trackingItemCount => getInt("tracking_items", backup: 0);
+  
+  bool get isBuilding => getBool("is_building");
 
     // Date of last update
     DateTime? get updatedDate {
@@ -320,7 +313,7 @@ class InvenTreeStockItem extends InvenTreeModel {
 
       // Backup if first value fails
       if (nm.isEmpty) {
-        nm = (jsondata["part__name"] ?? "") as String;
+        nm = getString("part__name");
       }
 
       return nm;
@@ -335,7 +328,7 @@ class InvenTreeStockItem extends InvenTreeModel {
       }
 
       if (desc.isEmpty) {
-        desc = (jsondata["part__description"] ?? "") as String;
+        desc = getString("part__description");
       }
 
       return desc;
@@ -349,7 +342,7 @@ class InvenTreeStockItem extends InvenTreeModel {
       }
 
       if (img.isEmpty) {
-        img = (jsondata["part__thumbnail"] ?? "") as String;
+        img = getString("part__thumbnail");
       }
 
       return img;
@@ -371,7 +364,7 @@ class InvenTreeStockItem extends InvenTreeModel {
 
       // Try a different approach
       if (thumb.isEmpty) {
-        thumb = (jsondata["part__thumbnail"] ?? "") as String;
+        thumb = getString("part__thumbnail");
       }
 
       // Still no thumbnail? Use the "no image" image
@@ -380,7 +373,7 @@ class InvenTreeStockItem extends InvenTreeModel {
       return thumb;
     }
 
-    int get supplierPartId => (jsondata["supplier_part"] ?? -1) as int;
+    int get supplierPartId => getInt("supplier_part");
 
     String get supplierImage {
       String thumb = "";
@@ -394,33 +387,15 @@ class InvenTreeStockItem extends InvenTreeModel {
       return thumb;
     }
 
-    String get supplierName {
-      String sname = "";
+    String get supplierName => getString("supplier_name", subKey: "supplier_detail");
 
-      if (jsondata.containsKey("supplier_detail")) {
-        sname = (jsondata["supplier_detail"]["supplier_name"] ?? "") as String;
-      }
+    String get units => getString("units", subKey: "part_detail");
 
-      return sname;
-    }
+    String get supplierSKU => getString("SKU", subKey: "supplier_part_detail");
 
-    String get units {
-      return (jsondata["part_detail"]?["units"] ?? "") as String;
-    }
+    String get serialNumber => getString("serial");
 
-    String get supplierSKU {
-      String sku = "";
-
-      if (jsondata.containsKey("supplier_part_detail")) {
-        sku = (jsondata["supplier_part_detail"]["SKU"] ?? "") as String;
-      }
-
-      return sku;
-    }
-
-    String get serialNumber => (jsondata["serial"] ?? "") as String;
-
-    double get quantity => double.tryParse(jsondata["quantity"].toString()) ?? 0;
+    double get quantity => getDouble("quantity");
 
     String quantityString({bool includeUnits = false}){
 
@@ -440,11 +415,11 @@ class InvenTreeStockItem extends InvenTreeModel {
       return q;
     }
 
-    double get allocated => double.tryParse(jsondata["allocated"].toString()) ?? 0;
+    double get allocated => getDouble("allocated");
 
     double get available => quantity - allocated;
 
-    int get locationId => (jsondata["location"] ?? -1) as int;
+    int get locationId => getInt("location");
 
     bool isSerialized() => serialNumber.isNotEmpty && quantity.toInt() == 1;
 
@@ -459,15 +434,14 @@ class InvenTreeStockItem extends InvenTreeModel {
     }
 
     String get locationName {
-      String loc = "";
 
       if (locationId == -1 || !jsondata.containsKey("location_detail")) return "Unknown Location";
 
-      loc = (jsondata["location_detail"]["name"] ?? "") as String;
+      String loc = getString("name", subKey: "location_detail");
 
       // Old-style name
       if (loc.isEmpty) {
-        loc = (jsondata["location__name"] ?? "") as String;
+        loc = getString("location__name");
       }
 
       return loc;
@@ -477,8 +451,7 @@ class InvenTreeStockItem extends InvenTreeModel {
 
       if (locationId == -1 || !jsondata.containsKey("location_detail")) return L10().locationNotSet;
 
-      String _loc = (jsondata["location_detail"]["pathstring"] ?? "") as String;
-
+      String _loc = getString("pathstring", subKey: "location_detail");
       if (_loc.isNotEmpty) {
         return _loc;
       } else {
@@ -497,9 +470,7 @@ class InvenTreeStockItem extends InvenTreeModel {
     }
 
     @override
-    InvenTreeModel createFromJson(Map<String, dynamic> json) {
-      return InvenTreeStockItem.fromJson(json);
-    }
+    InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeStockItem.fromJson(json);
 
     /*
    * Perform stocktake action:
@@ -601,9 +572,7 @@ class InvenTreeStockItemAttachment extends InvenTreeAttachment {
   String get URL => "stock/attachment/";
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
-    return InvenTreeStockItemAttachment.fromJson(json);
-  }
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeStockItemAttachment.fromJson(json);
 
 }
 
@@ -620,7 +589,7 @@ class InvenTreeStockLocation extends InvenTreeModel {
   @override
   List<String> get rolesRequired => ["stock_location"];
 
-  String get pathstring => (jsondata["pathstring"] ?? "") as String;
+  String get pathstring => getString("pathstring");
 
   @override
   Map<String, dynamic> formFields() {
@@ -658,10 +627,6 @@ class InvenTreeStockLocation extends InvenTreeModel {
   int get itemcount => (jsondata["items"] ?? 0) as int;
 
   @override
-  InvenTreeModel createFromJson(Map<String, dynamic> json) {
+  InvenTreeModel createFromJson(Map<String, dynamic> json) => InvenTreeStockLocation.fromJson(json);
 
-    var loc = InvenTreeStockLocation.fromJson(json);
-
-    return loc;
-  }
-}
+}

lib/l10n/app_en.arb

@@ -759,6 +759,9 @@
   "profileTapToCreate": "Tap to create or select a profile",
   "@profileTapToCreate": {},
 
+  "projectCode": "Project Code",
+  "@projectCode": {},
+
   "purchaseOrder": "Purchase Order",
   "@purchaseOrder": {},
 

lib/widget/purchase_order_detail.dart

@@ -43,6 +43,8 @@ class _PurchaseOrderDetailState extends RefreshableState<PurchaseOrderDetailWidg
 
   int attachmentCount = 0;
 
+  bool supportProjectCodes = false;
+
   @override
   String getAppBarTitle() => L10().purchaseOrder;
 
@@ -139,6 +141,8 @@ class _PurchaseOrderDetailState extends RefreshableState<PurchaseOrderDetailWidg
 
     lines = await order.getLineItems();
 
+    supportProjectCodes = api.supportsProjectCodes && await api.getGlobalBooleanSetting("PROJECT_CODES_ENABLED");
+
     completedLines = 0;
 
     for (var line in lines) {
@@ -157,12 +161,20 @@ class _PurchaseOrderDetailState extends RefreshableState<PurchaseOrderDetailWidg
   // Edit the currently displayed PurchaseOrder
   Future <void> editOrder(BuildContext context) async {
     var fields = order.formFields();
+
+    // Cannot edit supplier field from here
     fields.remove("supplier");
 
+    // Contact model not supported by server
     if (!api.supportsContactModel) {
       fields.remove("contact");
     }
 
+    // ProjectCode model not supported by server
+    if (!supportProjectCodes) {
+      fields.remove("project_code");
+    }
+
     order.editForm(
       context,
       L10().purchaseOrderEdit,
@@ -202,6 +214,14 @@ class _PurchaseOrderDetailState extends RefreshableState<PurchaseOrderDetailWidg
 
     tiles.add(headerTile(context));
 
+    if (supportProjectCodes && order.hasProjectCode) {
+      tiles.add(ListTile(
+        title: Text(L10().projectCode),
+        subtitle: Text("${order.projectCode} - ${order.projectCodeDescription}"),
+        leading: FaIcon(FontAwesomeIcons.list),
+      ));
+    }
+
     if (supplier != null) {
       tiles.add(ListTile(
         title: Text(L10().supplier),