Enabled nullability annotations in .Core project

Author: Sergio0694

samples/MvvmSample.Core/Models/Post.cs

@@ -11,55 +11,55 @@ namespace MvvmSample.Core.Models
     /// <summary>
     /// A class for a query for posts in a given subreddit.
     /// </summary>
-    public class PostsQueryResponse
+    public sealed class PostsQueryResponse
     {
         /// <summary>
         /// Gets or sets the listing data for the response.
         /// </summary>
         [JsonPropertyName("data")]
-        public PostListing Data { get; set; }
+        public PostListing? Data { get; init; }
     }
 
     /// <summary>
     /// A class for a Reddit listing of posts.
     /// </summary>
-    public class PostListing
+    public sealed class PostListing
     {
         /// <summary>
         /// Gets or sets the items in this listing.
         /// </summary>
         [JsonPropertyName("children")]
-        public IList<PostData> Items { get; set; }
+        public IList<PostData>? Items { get; init; }
     }
 
     /// <summary>
     /// A wrapping class for a post.
     /// </summary>
-    public class PostData
+    public sealed class PostData
     {
         /// <summary>
         /// Gets or sets the <see cref="Post"/> instance.
         /// </summary>
         [JsonPropertyName("data")]
-        public Post Data { get; set; }
+        public Post? Data { get; init; }
     }
 
     /// <summary>
     /// A simple model for a Reddit post.
     /// </summary>
-    public class Post
+    public sealed class Post
     {
         /// <summary>
         /// Gets or sets the title of the post.
         /// </summary>
         [JsonPropertyName("title")]
-        public string Title { get; set; }
+        public string? Title { get; init; }
 
         /// <summary>
         /// Gets or sets the URL to the post thumbnail, if present.
         /// </summary>
         [JsonPropertyName("thumbnail")]
-        public string Thumbnail { get; set; }
+        public string? Thumbnail { get; init; }
 
         /// <summary>
         /// Gets the text of the post.

samples/MvvmSample.Core/Models/System.Runtime.CompilerServices/IsExternalInit.cs

@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Reserved to be used by the compiler for tracking metadata.
+    /// This class should not be used by developers in source code.
+    /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    internal static class IsExternalInit
+    {
+    }
+}

samples/MvvmSample.Core/MvvmSample.Core.csproj

@@ -2,7 +2,8 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <LangVersion>8.0</LangVersion>
+    <LangVersion>9.0</LangVersion>
+    <Nullable>enable</Nullable>
     <UserSecretsId>4e66f7b4-01a8-4f00-8733-4ae6a08c741f</UserSecretsId>
   </PropertyGroup>
 

samples/MvvmSample.Core/Services/ISettingsService.cs

@@ -26,6 +26,6 @@ public interface ISettingsService
         /// <typeparam name="T">The type of the object to retrieve.</typeparam>
         /// <param name="key">The key associated to the requested object.</param>
         [Pure]
-        T GetValue<T>(string key);
+        T? GetValue<T>(string key);
     }
 }

samples/MvvmSample.Core/ViewModels/MessengerPageViewModel.cs

@@ -73,9 +73,9 @@ protected override void OnActivated()
             }
         }
 
-        private string username;
+        private string? username;
 
-        public string Username
+        public string? Username
         {
             get => username;
             private set => SetProperty(ref username, value);

samples/MvvmSample.Core/ViewModels/ObservableObjectPageViewModel.cs

@@ -20,23 +20,23 @@ public ObservableObjectPageViewModel()
         /// </summary>
         public ICommand ReloadTaskCommand { get; }
 
-        private string name;
+        private string? name;
 
         /// <summary>
         /// Gets or sets the name to display.
         /// </summary>
-        public string Name
+        public string? Name
         {
             get => name;
             set => SetProperty(ref name, value);
         }
 
-        private TaskNotifier myTask;
+        private TaskNotifier? myTask;
 
         /// <summary>
         /// Gets or sets the name to display.
         /// </summary>
-        public Task MyTask
+        public Task? MyTask
         {
             get => myTask;
             private set => SetPropertyAndNotifyOnCompletion(ref myTask, value);

samples/MvvmSample.Core/ViewModels/SamplePageViewModel.cs

@@ -18,7 +18,6 @@ namespace MvvmSample.Core.ViewModels
     /// </summary>
     public class SamplePageViewModel : ObservableObject
     {
-        private IReadOnlyDictionary<string, string> texts;
         /// <summary>
         /// The <see cref="IFilesService"/> instance currently in use.
         /// </summary>
@@ -34,7 +33,9 @@ public SamplePageViewModel()
         /// </summary>
         public IAsyncRelayCommand<string> LoadDocsCommand { get; }
 
-        public IReadOnlyDictionary<string, string> Texts 
+        private IReadOnlyDictionary<string, string>? texts;
+
+        public IReadOnlyDictionary<string, string>? Texts 
         { 
             get => texts; 
             set => SetProperty(ref texts, value); 
@@ -47,15 +48,17 @@ public IReadOnlyDictionary<string, string> Texts
         /// <returns>The text of the specified paragraph, or <see langword="null"/>.</returns>
         public string GetParagraph(string key)
         {
-            return Texts != null && Texts.TryGetValue(key, out var value) ? value : string.Empty;
+            return Texts is not null && Texts.TryGetValue(key, out var value) ? value : string.Empty;
         }
 
         /// <summary>
         /// Implements the logic for <see cref="LoadDocsCommand"/>.
         /// </summary>
         /// <param name="name">The name of the docs file to load.</param>
-        private async Task LoadDocsAsync(string name)
+        private async Task LoadDocsAsync(string? name)
         {
+            if (name is null) return;
+
             // Skip if the loading has already started
             if (!(LoadDocsCommand.ExecutionTask is null)) return;
 

samples/MvvmSample.Core/ViewModels/Widgets/PostWidgetViewModel.cs

@@ -14,12 +14,12 @@ namespace MvvmSample.Core.ViewModels.Widgets
     /// </summary>
     public sealed class PostWidgetViewModel : ObservableRecipient, IRecipient<PropertyChangedMessage<Post>>
     {
-        private Post post;
+        private Post? post;
 
         /// <summary>
         /// Gets the currently selected post, if any.
         /// </summary>
-        public Post Post
+        public Post? Post
         {
             get => post;
             private set => SetProperty(ref post, value);

samples/MvvmSample.Core/ViewModels/Widgets/SubredditWidgetViewModel.cs

@@ -32,7 +32,7 @@ public sealed class SubredditWidgetViewModel : ObservableRecipient
         /// <summary>
         /// An <see cref="AsyncLock"/> instance to avoid concurrent requests.
         /// </summary>
-        private readonly AsyncLock LoadingLock = new AsyncLock();
+        private readonly AsyncLock LoadingLock = new();
 
         /// <summary>
         /// Creates a new <see cref="SubredditWidgetViewModel"/> instance.
@@ -52,7 +52,7 @@ public SubredditWidgetViewModel()
         /// <summary>
         /// Gets the collection of loaded posts.
         /// </summary>
-        public ObservableCollection<Post> Posts { get; } = new ObservableCollection<Post>();
+        public ObservableCollection<Post> Posts { get; } = new();
 
         /// <summary>
         /// Gets the collection of available subreddits to pick from.
@@ -83,12 +83,12 @@ public string SelectedSubreddit
             }
         }
 
-        private Post selectedPost;
+        private Post? selectedPost;
 
         /// <summary>
-        /// Gets or sets the currently selected subreddit.
+        /// Gets or sets the currently selected post, if any.
         /// </summary>
-        public Post SelectedPost
+        public Post? SelectedPost
         {
             get => selectedPost;
             set => SetProperty(ref selectedPost, value, true);
@@ -107,9 +107,9 @@ private async Task LoadPostsAsync()
 
                     Posts.Clear();
 
-                    foreach (var item in response.Data.Items)
+                    foreach (var item in response.Data!.Items!)
                     {
-                        Posts.Add(item.Data);
+                        Posts.Add(item.Data!);
                     }
                 }
                 catch