Add InvenTreeObject class for getting API data

lib/inventree_object.dart

@@ -0,0 +1,144 @@
+import 'api.dart';
+
+import 'dart:convert';
+
+import 'package:path/path.dart' as path;
+import 'package:http/http.dart' as http;
+
+
+/**
+ * The InvenTreeObject class provides a base-level object
+ * for interacting with InvenTree data.
+ */
+class InvenTreeObject {
+
+  // Override the endpoint URL for each subclass
+  String _URL = "";
+  String _name = "InvenTree";
+
+  // JSON data which defines this object
+  Map<String, dynamic> _data = {};
+
+  // Accessor for the API
+  var api = InvenTreeAPI();
+
+  // Default empty object constructor
+  InvenTreeObject() {
+    _data.clear();
+  }
+
+  // Construct an InvenTreeObject from a JSON data object
+  InvenTreeObject.fromJson(Map<String, dynamic> json) {
+
+    // Store the json object
+    _data = json;
+
+  }
+
+  int get pk {
+    return _data['pk'] ?? -1;
+  }
+
+  // Create a new object from JSON data (not a constructor!)
+  InvenTreeObject _createFromJson(Map<String, dynamic> json) {
+      print("creating new object");
+
+      var obj = InvenTreeObject.fromJson(json);
+
+      return obj;
+  }
+
+  String get url{ return path.join(_URL, pk.toString()); }
+
+  // Return list of objects from the database, with optional filters
+  Future<http.Response> list({Map<String, String> filters}) async {
+
+    if (filters == null) {
+      filters = {};
+    }
+
+    print("Listing endpoint: " + _URL);
+
+    // TODO - Add "timeout"
+    // TODO - Add error catching
+
+    InvenTreeAPI().get(_URL, params:filters).then((http.Response response) {
+
+     final data = json.decode(response.body);
+
+     for (var d in data) {
+       print(d);
+
+       var obj = _createFromJson(d);
+
+       if (obj is InvenTreePart) {
+         print("Part -> " + obj.name + obj.description);
+       } else {
+         print("Not part :'(");
+         print(obj.runtimeType);
+       }
+     }
+
+     // var obj = _createFromJson(data);
+
+    });
+  }
+
+
+  // Provide a listing of objects at the endpoint
+  // TODO - Static function which returns a list of objects (of this class)
+
+  // TODO - Define a 'delete' function
+
+  // TODO - Define a 'save' / 'update' function
+
+
+}
+
+
+class InvenTreePart extends InvenTreeObject {
+
+  @override
+  String _URL = "part/";
+
+  @override
+  String _name = "part";
+
+  String get name {
+    return _data['name'] ?? '';
+  }
+
+  String get description {
+    return _data['description'] ?? '';
+  }
+
+  int get categoryId {
+    return _data['category'] as int ?? -1;
+  }
+
+  String get categoryName {
+    return _data['category__name'] ?? '';
+  }
+
+  InvenTreePart() : super();
+
+  InvenTreePart.fromJson(Map<String, dynamic> json) : super.fromJson(json) {
+
+  }
+
+  @override
+  InvenTreeObject _createFromJson(Map<String, dynamic> json) {
+
+    var part = InvenTreePart.fromJson(json);
+
+    print("creating new part!");
+    print(json);
+
+    return part;
+
+  }
+
+  // TODO - Is there a way of making this "list" function generic to the InvenTreeObject class?
+  // In an ideal world it would return a list of
+  //List<InvenTreePart> list()
+}