AccountPage layout and local storage functionality

App.razor

-<Router AppAssembly="@typeof(Program).Assembly">
-    <Found Context="routeData">
-        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
-    </Found>
-    <NotFound>
-        <LayoutView Layout="@typeof(MainLayout)">
-            <p>Sorry, there's nothing at this address.</p>
-        </LayoutView>
-    </NotFound>
-</Router>
+<UserDataComponent>
+    <Router AppAssembly="@typeof(Program).Assembly">
+        <Found Context="routeData">
+            <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
+        </Found>
+        <NotFound>
+            <LayoutView Layout="@typeof(MainLayout)">
+                <p>Sorry, there's nothing at this address.</p>
+            </LayoutView>
+        </NotFound>
+    </Router>
+</UserDataComponent>

Pages/AccountPage.razor

 @page "/account"
 @inject NavigationManager NavigationManager
+@inject UserDataProvider UserDataProvider
 
-<h1>Counter</h1>
+<div class="row px-3 h-100">
+    <div class="row no-gutters align-items-start w-100">
+        <div class="row no-gutters w-100" style="padding-top:2em">
+            <div class="col-6" style="padding-right:0.5em">
+                <MatStringField Class="w-100" Label="Firstname" Outlined="true" type="text" @bind-Value="@State.Firstname"></MatStringField>
+            </div>
+            <div class="col-6" style="padding-left:0.5em">
+                <MatStringField Class="w-100" Label="Lastname" Outlined="true"  type="text" @bind-Value="@State.Lastname"></MatStringField>
+            </div>
+        </div>
+        <div class="row no-gutters align-items-center w-100">
+            <div class="col-12">
+                <MatStringField Class="w-100" Label="Address" Outlined="true"></MatStringField>
+            </div>
+        </div>
+        <div class="row no-gutters align-items-center w-100">
+            <div class="col-4" style="padding-right:0.5em">
+                <MatStringField Class="w-100" Label="Zip" Outlined="true"></MatStringField>
+            </div>
+            <div class="col-8" style="padding-left:0.5em">
+                <MatStringField Class="w-100" Label="City" Outlined="true"></MatStringField>
+            </div>
+        </div>
+        <div class="row no-gutters align-items-center w-100">
+            <div class="col-12">
+                <MatStringField Class="w-100" Label="Phone" Outlined="true"></MatStringField>
+            </div>
+        </div>
+        <div class="row no-gutters align-items-center w-100">
+            <div class="col-12">
+                <MatStringField Class="w-100" Label="E-Mail" Outlined="true"></MatStringField>
+            </div>
+        </div>
+    </div>
+    <div class="row no-gutters align-items-end justify-content-center w-100" style="padding-bottom:2em">
+        <MatButton Class="w-100" Raised="true" @onclick="SaveUserData">Speichern</MatButton>
+    </div>
+</div>
 
-<p>Current count: @currentCount</p>
 
-<MatList>
-    <MatListItem>
-        <MatButton Raised="true" @onclick="IncrementCount">Click me!</MatButton>
-    </MatListItem>
-</MatList>
 
 
 @code {
-    private int currentCount = 0;
 
-    private void IncrementCount() {
-        currentCount++;
+    async private void SaveUserData() {
+        await UserDataProvider.Save();
     }
+
+    [CascadingParameter]
+    public UserData State { get; set; }
 }
 

Program.cs

             builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
             builder.Services.AddMatBlazor();
             builder.Services.AddSingleton<AppState>();
+            builder.Services.AddScoped<UserDataProvider>();
 
             await builder.Build().RunAsync();
         }

Shared/UserData.cs

+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace CaritasPWA.Shared {
+    // The class that stores the user settings
+    public class UserData : INotifyPropertyChanged {
+        private string firstname;
+        private string lastname;
+
+        public string Firstname {
+            get => firstname; 
+            set {
+                firstname = value;
+                RaisePropertyChanged();
+            }
+        }
+
+        public string Lastname {
+            get => lastname; 
+            set {
+                lastname = value;
+                RaisePropertyChanged();
+            }
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        private void RaisePropertyChanged([CallerMemberName] string propertyName = null) {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}

Shared/UserDataComponent.razor

+@inject UserDataProvider UserDataProvider
+@implements IDisposable
+
+@if (state == null) {
+    <p>loading...</p>
+} else {
+    <CascadingValue Value="@state" IsFixed="false">@ChildContent</CascadingValue>
+}
+
+@code{
+    private UserData state = null;
+
+    [Parameter]
+    public RenderFragment ChildContent { get; set; }
+
+    protected override async Task OnInitializedAsync() {
+        UserDataProvider.Changed += UserDataChanged;
+        await Refresh();
+    }
+
+    public void Dispose() {
+        UserDataProvider.Changed -= UserDataChanged;
+    }
+
+    private async void UserDataChanged(object sender, EventArgs e) {
+        await InvokeAsync(async () => {
+            await Refresh();
+            StateHasChanged();
+        });
+    }
+
+    private async Task Refresh() {
+        state = await UserDataProvider.Get();
+    }
+}

Shared/UserDataProvider.cs

+using Microsoft.JSInterop;
+using System;
+using System.ComponentModel;
+using System.Threading.Tasks;
+
+namespace CaritasPWA.Shared {
+    public sealed class UserDataProvider {
+        private const string KeyName = "state";
+
+        private readonly IJSRuntime _jsRuntime;
+        private bool _initialized;
+        private UserData _data;
+
+        public event EventHandler Changed;
+
+        public bool AutoSave { get; set; } = true;
+
+        public UserDataProvider(IJSRuntime jsRuntime) {
+            _jsRuntime = jsRuntime;
+        }
+
+        public async ValueTask<UserData> Get() {
+            if (_data != null)
+                return _data;
+
+            // Register the Storage event handler. This handler calls OnStorageUpdated when the storage changed.
+            // This way, you can reload the settings when another instance of the application (tab / window) save the settings
+            if (!_initialized) {
+                // Create a reference to the current object, so the JS function can call the public method "OnStorageUpdated"
+                var reference = DotNetObjectReference.Create(this);
+                await _jsRuntime.InvokeVoidAsync("BlazorRegisterStorageEvent", reference);
+                _initialized = true;
+            }
+
+            // Read the JSON string that contains the data from the local storage
+            UserData result;
+            var str = await _jsRuntime.InvokeAsync<string>("BlazorGetLocalStorage", KeyName);
+            if (str != null) {
+                result = System.Text.Json.JsonSerializer.Deserialize<UserData>(str) ?? new UserData();
+            } else {
+                result = new UserData();
+            }
+
+            // Register the OnPropertyChanged event, so it automatically persists the settings as soon as a value is changed
+            result.PropertyChanged += OnPropertyChanged;
+            _data = result;
+            return result;
+        }
+
+        public async Task Save() {
+            var json = System.Text.Json.JsonSerializer.Serialize(_data);
+            await _jsRuntime.InvokeVoidAsync("BlazorSetLocalStorage", KeyName, json);
+        }
+
+        // Automatically persist the settings when a property changed
+        private async void OnPropertyChanged(object sender, PropertyChangedEventArgs e) {
+            if (AutoSave) {
+                await Save();
+            }
+        }
+
+        // This method is called from BlazorRegisterStorageEvent when the storage changed
+        [JSInvokable]
+        public void OnStorageUpdated(string key) {
+            if (key == KeyName) {
+                // Reset the settings. The next call to Get will reload the data
+                _data = null;
+                Changed?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}

wwwroot/index.html

 </head>
 
 <body>
+
     <app>Loading...</app>
 
     <div id="blazor-error-ui">
     </div>
     <script src="_framework/blazor.webassembly.js"></script>
     <script>navigator.serviceWorker.register('service-worker.js');</script>
+    <script>
+        function BlazorSetLocalStorage(key, value) {
+            localStorage.setItem(key, value);
+        }
+
+        function BlazorGetLocalStorage(key) {
+            return localStorage.getItem(key);
+        }
+
+        function BlazorRegisterStorageEvent(component) {
+            window.addEventListener("storage", async e => {
+                await component.invokeMethodAsync("OnStorageUpdated", e.key);
+            });
+        }
+    </script>
+
 </body>
 
+
 </html>
+
+