Update the name of an existing shopping list

lib/components/list_item.dart

@@ -10,7 +10,7 @@ class ListItem extends StatelessWidget {
   final onTap;
   final onInfoTap;
 
-  ListItem({Key key, @required this.item, this.listType, this.count, this.onTap, this.onInfoTap});
+  ListItem({Key key, this.item: "Unknown", this.listType, this.count, this.onTap, this.onInfoTap});
 
   buildDateString(date) {
     return DateFormat.yMMMd().format(DateTime.parse(date));
@@ -26,7 +26,7 @@ class ListItem extends StatelessWidget {
   buildTitleString() {
     if (listType == 'item') {
       return item.name + (item.quantity > 1 ? ' (' + item.quantity.toString() + ')' : '');
-    } else {  // crossed off, shopping list, store
+    } else { // crossed off, shopping list, store
       return item.name;
     }
   }

lib/db/database_manager.dart

@@ -20,11 +20,14 @@ class DatabaseManager {
     shoppingLists.document(docRef.documentID).updateData({'id':docRef.documentID});
     return docRef;
   }
-
-  /*
-  Future<void> updateShoppingList(String id, ShoppingListDTO shoppingList) {
-    return shoppingLists.document(id).updateData(shoppingList.toJson());
-  } */
+
+  Future<DocumentReference> updateShoppingList(String id, ShoppingListDTO shoppingList) async {
+    DocumentReference docRef = shoppingLists.document(id);
+    Firestore.instance.runTransaction((transaction) async {
+      await transaction.update(docRef, shoppingList.toJson());
+    });
+    return docRef;
+  }
 
   Future<DocumentReference> addStore(StoreDTO store) async {
     DocumentReference docRef = await stores.add(store.toJson());

lib/db/shopping_list_dto.dart

@@ -6,7 +6,7 @@ class ShoppingListDTO {
   List itemIDs;
 
   String toString() {
-    return 'id: $id, name: $name, date: $date, storeIDs: $itemIDs';
+    return 'id: $id, name: $name, date: $date, itemIDs: $itemIDs';
   }
 
   Map<String, dynamic> toJson() => <String, dynamic> {

lib/views/existing_list.dart

@@ -1,49 +1,98 @@
 import 'package:flutter/material.dart';
+import 'package:grocery_go/db/database_manager.dart';
+import 'package:grocery_go/db/shopping_list_dto.dart';
 import 'package:grocery_go/models/shopping_list.dart';
 
 class ExistingListArguments {
   final ShoppingList list;
   ExistingListArguments(this.list);
 }
 
-class ExistingList extends StatelessWidget {
-
+class ExistingList extends StatefulWidget {
   static const routeName = '/existingList';
+  ExistingList({Key key});
 
-  void updateList (BuildContext context) {
-    print("Updating list");
-    Navigator.of(context).pop();
-  }
+  @override
+  _ExistingListState createState() => _ExistingListState();
+}
 
+class _ExistingListState extends State<ExistingList> {
   @override
   Widget build(BuildContext context) {
-
-    final ExistingListArguments args = ModalRoute.of(context).settings.arguments;
-
     return Scaffold(
       appBar: AppBar(
-        title: Text("Edit list: " + args.list.name),
+        title: Text("Edit shopping list"),
       ),
       body: Center(
-        child: Column(
-          children: [
-            Padding(
-              padding: EdgeInsets.fromLTRB(10, 20, 10, 10),
-              child: TextFormField(
-                autofocus: true,
-                initialValue: args.list.name,
-                decoration: InputDecoration(
-                    labelText: 'List name',
-                    border: OutlineInputBorder()),
-              ),
-            ),
-            RaisedButton(
-              onPressed: () => updateList(context),
-              child: Text('Save list'),
-            ),
-          ],
+        child: Padding(
+          padding: EdgeInsets.all(20),
+          child: UpdateShoppingListForm(),
         ),
       ),
     );
   }
+}
+
+class UpdateShoppingListForm extends StatefulWidget {
+  @override
+  _UpdateShoppingListFormState createState() => _UpdateShoppingListFormState();
+}
+
+class _UpdateShoppingListFormState extends State<UpdateShoppingListForm> {
+  final formKey = GlobalKey<FormState>();
+  final DatabaseManager db = DatabaseManager();
+
+  final updateShoppingListFields = ShoppingListDTO();
+
+  String validateStringInput(String value) {
+    if (value.isEmpty) {
+      return 'Please enter a name';
+    } else return null;
+  }
+
+  void updateList(BuildContext context, list) async {
+    final formState = formKey.currentState;
+
+    if (formState.validate()) {
+      formKey.currentState.save();
+
+      // take the existing data
+      updateShoppingListFields.id = list.id;
+      updateShoppingListFields.itemIDs = list.itemIDs;
+      // update the last edited date
+      updateShoppingListFields.date = DateTime.now().toString();
+      await db.updateShoppingList(list.id, updateShoppingListFields);
+      Navigator.of(context).pop();
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+
+    final ExistingListArguments args = ModalRoute.of(context).settings.arguments;
+
+    return Form(
+      key: formKey,
+      child: Column(
+        children: [
+          TextFormField(
+            autofocus: true,
+            initialValue: args.list.name,
+            decoration: InputDecoration(
+                labelText: 'List name',
+                border: OutlineInputBorder()
+            ),
+            validator: (value) => validateStringInput(value),
+            onSaved: (value) {
+              updateShoppingListFields.name = value;
+            }
+          ),
+          RaisedButton(
+            onPressed: () => updateList(context, args.list),
+            child: Text('Update list'),
+          ),
+        ],
+      ),
+    );
+  }
 }