TempData support for Blazor

src/Components/Components/src/ITempData.cs

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components;
+
+/// <summary>
+/// Provides a dictionary for storing data that is needed for subsequent requests.
+/// Data stored in TempData is automatically removed after it is read unless
+/// <see cref="Keep()"/> or <see cref="Keep(string)"/> is called, or it is accessed via <see cref="Peek(string)"/>.
+/// </summary>
+public interface ITempData
+{
+    /// <summary>
+    /// Gets or sets the value associated with the specified key.
+    /// </summary>
+    object? this[string key] { get; set; }
+
+    /// <summary>
+    /// Gets the value associated with the specified key and then schedules it for deletion.
+    /// </summary>
+    object? Get(string key);
+
+    /// <summary>
+    /// Gets the value associated with the specified key without scheduling it for deletion.
+    /// </summary>
+    object? Peek(string key);
+
+    /// <summary>
+    /// Makes all of the keys currently in TempData persist for another request.
+    /// </summary>
+    void Keep();
+
+    /// <summary>
+    /// Makes the element with the <paramref name="key"/> persist for another request.
+    /// </summary>
+    void Keep(string key);
+}

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -1,4 +1,21 @@
 #nullable enable
+Microsoft.AspNetCore.Components.ITempData
+Microsoft.AspNetCore.Components.ITempData.Get(string! key) -> object?
+Microsoft.AspNetCore.Components.ITempData.Keep() -> void
+Microsoft.AspNetCore.Components.ITempData.Keep(string! key) -> void
+Microsoft.AspNetCore.Components.ITempData.this[string! key].get -> object?
+Microsoft.AspNetCore.Components.ITempData.this[string! key].set -> void
+Microsoft.AspNetCore.Components.ITempData.Peek(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData
+Microsoft.AspNetCore.Components.TempData.Get(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData.GetDataToSave() -> System.Collections.Generic.IDictionary<string!, object?>!
+Microsoft.AspNetCore.Components.TempData.Keep() -> void
+Microsoft.AspNetCore.Components.TempData.Keep(string! key) -> void
+Microsoft.AspNetCore.Components.TempData.LoadDataFromCookie(System.Collections.Generic.IDictionary<string!, object?>! data) -> void
+Microsoft.AspNetCore.Components.TempData.Peek(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData.TempData() -> void
+Microsoft.AspNetCore.Components.TempData.this[string! key].get -> object?
+Microsoft.AspNetCore.Components.TempData.this[string! key].set -> void
 *REMOVED*Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Components.ResourceAssetProperty!>? properties) -> void
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.get -> bool
 *REMOVED*Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.set -> void

src/Components/Components/src/TempData.cs

@@ -0,0 +1,76 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components;
+
+/// <inheritdoc/>
+public class TempData : ITempData
+{
+    private readonly Dictionary<string, object?> _data = new();
+    private readonly HashSet<string> _retainedKeys = new();
+
+    /// <inheritdoc/>
+    public object? this[string key]
+    {
+        get => Get(key);
+        set
+        {
+            _data[key] = value;
+            _retainedKeys.Add(key);
+        }
+    }
+
+    /// <inheritdoc/>
+    public object? Get(string key)
+    {
+        _retainedKeys.Remove(key);
+        return _data.GetValueOrDefault(key);
+    }
+
+    /// <inheritdoc/>
+    public object? Peek(string key)
+    {
+        return _data.GetValueOrDefault(key);
+    }
+
+    /// <inheritdoc/>
+    public void Keep()
+    {
+        foreach (var key in _data.Keys)
+        {
+            _retainedKeys.Add(key);
+        }
+    }
+
+    /// <inheritdoc/>
+    public void Keep(string key)
+    {
+        if (_data.ContainsKey(key))
+        {
+            _retainedKeys.Add(key);
+        }
+    }
+
+    /// <inheritdoc/>
+    public IDictionary<string, object?> GetDataToSave()
+    {
+        var dataToSave = new Dictionary<string, object?>();
+        foreach (var key in _retainedKeys)
+        {
+            dataToSave[key] = _data[key];
+        }
+        return dataToSave;
+    }
+
+    /// <inheritdoc/>
+    public void LoadDataFromCookie(IDictionary<string, object?> data)
+    {
+        _data.Clear();
+        _retainedKeys.Clear();
+        foreach (var kvp in data)
+        {
+            _data[kvp.Key] = kvp.Value;
+            _retainedKeys.Add(kvp.Key);
+        }
+    }
+}

src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs

@@ -74,6 +74,26 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
         services.TryAddScoped<WebAssemblySettingsEmitter>();
         services.TryAddScoped<ResourcePreloadService>();
+        services.TryAddCascadingValue(sp =>
+        {
+            var httpContext = sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext;
+            if (httpContext is null)
+            {
+                return null!;
+            }
+            var key = typeof(ITempData);
+            if (!httpContext.Items.TryGetValue(key, out var tempData))
+            {
+                var tempDataInstance = TempDataService.Load(httpContext);
+                httpContext.Items[key] = tempDataInstance;
+                httpContext.Response.OnStarting(() =>
+                {
+                    TempDataService.Save(httpContext, tempDataInstance);
+                    return Task.CompletedTask;
+                });
+            }
+            return (ITempData)httpContext.Items[key]!;
+        });
 
         services.TryAddScoped<ResourceCollectionProvider>();
         RegisterPersistentComponentStateServiceCollectionExtensions.AddPersistentServiceRegistration<ResourceCollectionProvider>(services, RenderMode.InteractiveWebAssembly);

src/Components/Endpoints/src/DependencyInjection/TempDataService.cs

@@ -0,0 +1,154 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Text.Json;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+internal sealed class TempDataService
+{
+    private const string CookieName = ".AspNetCore.Components.TempData";
+
+    public TempDataService()
+    {
+        // TO-DO: Add encoding later if needed
+    }
+
+    public static TempData Load(HttpContext httpContext)
+    {
+        var returnTempData = new TempData();
+        var serializedDataFromCookie = httpContext.Request.Cookies[CookieName];
+        if (serializedDataFromCookie is null)
+        {
+            return returnTempData;
+        }
+
+        var dataFromCookie = JsonSerializer.Deserialize<Dictionary<string, JsonElement>>(serializedDataFromCookie);
+        if (dataFromCookie is null)
+        {
+            return returnTempData;
+        }
+
+        var convertedData = new Dictionary<string, object?>();
+        foreach (var kvp in dataFromCookie)
+        {
+            convertedData[kvp.Key] = ConvertJsonElement(kvp.Value);
+        }
+
+        returnTempData.LoadDataFromCookie(convertedData);
+        return returnTempData;
+    }
+
+    private static object? ConvertJsonElement(JsonElement element)
+    {
+        switch (element.ValueKind)
+        {
+            case JsonValueKind.String:
+                if (element.TryGetGuid(out var guid))
+                {
+                    return guid;
+                }
+                if (element.TryGetDateTime(out var dateTime))
+                {
+                    return dateTime;
+                }
+                return element.GetString();
+            case JsonValueKind.Number:
+                return element.GetInt32();
+            case JsonValueKind.True:
+            case JsonValueKind.False:
+                return element.GetBoolean();
+            case JsonValueKind.Null:
+                return null;
+            case JsonValueKind.Array:
+                return DeserializeArray(element);
+            case JsonValueKind.Object:
+                return DeserializeDictionaryEntry(element);
+            default:
+                throw new InvalidOperationException($"TempData cannot deserialize value of type '{element.ValueKind}'.");
+        }
+    }
+
+    private static object? DeserializeArray(JsonElement arrayElement)
+    {
+        var arrayLength = arrayElement.GetArrayLength();
+        if (arrayLength == 0)
+        {
+            return null;
+        }
+        if (arrayElement[0].ValueKind == JsonValueKind.String)
+        {
+            var array = new List<string?>(arrayLength);
+            foreach (var item in arrayElement.EnumerateArray())
+            {
+                array.Add(item.GetString());
+            }
+            return array.ToArray();
+        }
+        else if (arrayElement[0].ValueKind == JsonValueKind.Number)
+        {
+            var array = new List<int>(arrayLength);
+            foreach (var item in arrayElement.EnumerateArray())
+            {
+                array.Add(item.GetInt32());
+            }
+            return array.ToArray();
+        }
+        throw new InvalidOperationException($"TempData cannot deserialize array of type '{arrayElement[0].ValueKind}'.");
+    }
+
+    private static Dictionary<string, string?> DeserializeDictionaryEntry(JsonElement objectElement)
+    {
+        var dictionary = new Dictionary<string, string?>(StringComparer.Ordinal);
+        foreach (var item in objectElement.EnumerateObject())
+        {
+            dictionary[item.Name] = item.Value.GetString();
+        }
+        return dictionary;
+    }
+
+    public static void Save(HttpContext httpContext, TempData tempData)
+    {
+        var dataToSave = tempData.GetDataToSave();
+        foreach (var kvp in dataToSave)
+        {
+            if (!CanSerializeType(kvp.Value?.GetType() ?? typeof(object)))
+            {
+                throw new InvalidOperationException($"TempData cannot store values of type '{kvp.Value?.GetType()}'.");
+            }
+        }
+
+        if (dataToSave.Count == 0)
+        {
+            httpContext.Response.Cookies.Delete(CookieName, new CookieOptions
+            {
+                Path = httpContext.Request.PathBase.HasValue ? httpContext.Request.PathBase.Value : "/",
+            });
+            return;
+        }
+        httpContext.Response.Cookies.Append(CookieName, JsonSerializer.Serialize(dataToSave), new CookieOptions
+        {
+            HttpOnly = true,
+            IsEssential = true,
+            SameSite = SameSiteMode.Lax,
+            Secure = httpContext.Request.IsHttps,
+            Path = httpContext.Request.PathBase.HasValue ? httpContext.Request.PathBase.Value : "/",
+        });
+    }
+
+    private static bool CanSerializeType(Type type)
+    {
+        type = Nullable.GetUnderlyingType(type) ?? type;
+        return
+            type.IsEnum ||
+            type == typeof(int) ||
+            type == typeof(string) ||
+            type == typeof(bool) ||
+            type == typeof(DateTime) ||
+            type == typeof(Guid) ||
+            typeof(ICollection<int>).IsAssignableFrom(type) ||
+            typeof(ICollection<string>).IsAssignableFrom(type) ||
+            typeof(IDictionary<string, string>).IsAssignableFrom(type);
+    }
+}