initial commit

Gallery.Share/ViewModels/NewItemViewModel.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Windows.Input;
+using Gallery.Models;
+using Xamarin.Forms;
+
+namespace Gallery.ViewModels
+{
+    public class NewItemViewModel : BaseViewModel
+    {
+        private string text;
+        private string description;
+
+        public NewItemViewModel()
+        {
+            SaveCommand = new Command(OnSave, ValidateSave);
+            CancelCommand = new Command(OnCancel);
+            this.PropertyChanged +=
+                (_, __) => SaveCommand.ChangeCanExecute();
+        }
+
+        private bool ValidateSave()
+        {
+            return !String.IsNullOrWhiteSpace(text)
+                && !String.IsNullOrWhiteSpace(description);
+        }
+
+        public string Text
+        {
+            get => text;
+            set => SetProperty(ref text, value);
+        }
+
+        public string Description
+        {
+            get => description;
+            set => SetProperty(ref description, value);
+        }
+
+        public Command SaveCommand { get; }
+        public Command CancelCommand { get; }
+
+        private async void OnCancel()
+        {
+            // This will pop the current page off the navigation stack
+            await Shell.Current.GoToAsync("..");
+        }
+
+        private async void OnSave()
+        {
+            Item newItem = new Item()
+            {
+                Id = Guid.NewGuid().ToString(),
+                Text = Text,
+                Description = Description
+            };
+
+            await DataStore.AddItemAsync(newItem);
+
+            // This will pop the current page off the navigation stack
+            await Shell.Current.GoToAsync("..");
+        }
+    }
+}