changed up the way that ingredients can be added

lib/example_data.dart

@@ -0,0 +1,27 @@
+import 'package:rezepte/models/unit.dart';
+
+import 'models/ingredient.dart';
+import 'constants.dart' as constants;
+
+final List<Unit> _weightAndCount = constants.units
+    .where((element) =>
+        element.type == UnitType.weight || element.type == UnitType.count)
+    .toList();
+
+final List<Unit> _weight = constants.units
+    .where((element) => element.type == UnitType.weight)
+    .toList();
+
+final List<Unit> _count =
+    constants.units.where((element) => element.type == UnitType.count).toList();
+
+final List<Unit> _fluid =
+    constants.units.where((element) => element.type == UnitType.fluid).toList();
+
+final List<Ingredient> exampleIngredients = [
+  Ingredient(title: 'Karotte', possibleUnits: _weightAndCount),
+  Ingredient(title: 'Kartoffel', possibleUnits: _weightAndCount),
+  Ingredient(title: 'Kaffeebohnen', possibleUnits: _weight),
+  Ingredient(title: 'Milch', possibleUnits: _fluid),
+  Ingredient(title: 'Limettenblätter', possibleUnits: _count),
+];