TempData support for Blazor

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

@@ -74,6 +74,7 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
         services.TryAddScoped<WebAssemblySettingsEmitter>();
         services.TryAddScoped<ResourcePreloadService>();
+        services.AddTempDataValueProvider();
 
         services.TryAddScoped<ResourceCollectionProvider>();
         RegisterPersistentComponentStateServiceCollectionExtensions.AddPersistentServiceRegistration<ResourceCollectionProvider>(services, RenderMode.InteractiveWebAssembly);

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

@@ -0,0 +1,216 @@
+// 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.DataProtection;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+internal sealed partial class TempDataService
+{
+    private const string CookieName = ".AspNetCore.Components.TempData";
+    private const string PurposeString = "Microsoft.AspNetCore.Components.Endpoints.TempDataService";
+    private const int MaxEncodedLength = 4050;
+
+    private static IDataProtector GetDataProtector(HttpContext httpContext)
+    {
+        var dataProtectionProvider = httpContext.RequestServices.GetRequiredService<IDataProtectionProvider>();
+        return dataProtectionProvider.CreateProtector(PurposeString);
+    }
+
+    public static TempData CreateEmpty(HttpContext httpContext)
+    {
+        return new TempData(() => Load(httpContext));
+    }
+
+    public static TempData Load(HttpContext httpContext)
+    {
+        try
+        {
+            var returnTempData = new TempData();
+            var serializedDataFromCookie = httpContext.Request.Cookies[CookieName];
+            if (serializedDataFromCookie is null)
+            {
+                return returnTempData;
+            }
+
+            var protectedBytes = WebEncoders.Base64UrlDecode(serializedDataFromCookie);
+            var unprotectedBytes = GetDataProtector(httpContext).Unprotect(protectedBytes);
+
+            var dataFromCookie = JsonSerializer.Deserialize<Dictionary<string, JsonElement>>(unprotectedBytes);
+
+            if (dataFromCookie is null)
+            {
+                return returnTempData;
+            }
+
+            var convertedData = new Dictionary<string, object?>();
+            foreach (var kvp in dataFromCookie)
+            {
+                convertedData[kvp.Key] = ConvertJsonElement(kvp.Value);
+            }
+
+            returnTempData.Load(convertedData);
+            return returnTempData;
+        }
+        catch (Exception ex)
+        {
+            // If any error occurs during loading (e.g. data protection key changed, malformed cookie),
+            // return an empty TempData dictionary.
+            if (httpContext.RequestServices.GetService<ILogger<TempDataService>>() is { } logger)
+            {
+                Log.TempDataCookieLoadFailure(logger, CookieName, ex);
+            }
+
+            httpContext.Response.Cookies.Delete(CookieName, new CookieOptions
+            {
+                Path = httpContext.Request.PathBase.HasValue ? httpContext.Request.PathBase.Value : "/",
+            });
+            return new TempData();
+        }
+    }
+
+    public static void Save(HttpContext httpContext, TempData tempData)
+    {
+        var dataToSave = tempData.Save();
+        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;
+        }
+
+        var bytes = JsonSerializer.SerializeToUtf8Bytes(dataToSave);
+        var protectedBytes = GetDataProtector(httpContext).Protect(bytes);
+        var encodedValue = WebEncoders.Base64UrlEncode(protectedBytes);
+
+        if (encodedValue.Length > MaxEncodedLength)
+        {
+            if (httpContext.RequestServices.GetService<ILogger<TempDataService>>() is { } logger)
+            {
+                Log.TempDataCookieSaveFailure(logger, CookieName);
+            }
+
+            httpContext.Response.Cookies.Delete(CookieName, new CookieOptions
+            {
+                Path = httpContext.Request.PathBase.HasValue ? httpContext.Request.PathBase.Value : "/",
+            });
+            return;
+        }
+
+        httpContext.Response.Cookies.Append(CookieName, encodedValue, new CookieOptions
+        {
+            HttpOnly = true,
+            IsEssential = true,
+            SameSite = SameSiteMode.Lax,
+            Secure = httpContext.Request.IsHttps,
+            Path = httpContext.Request.PathBase.HasValue ? httpContext.Request.PathBase.Value : "/",
+        });
+    }
+
+    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;
+    }
+
+    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);
+    }
+
+    private static partial class Log
+    {
+        [LoggerMessage(3, LogLevel.Warning, "The temp data cookie {CookieName} could not be loaded.", EventName = "TempDataCookieLoadFailure")]
+        public static partial void TempDataCookieLoadFailure(ILogger logger, string cookieName, Exception exception);
+
+        [LoggerMessage(3, LogLevel.Warning, "The temp data cookie {CookieName} could not be saved, because it is too large to fit in a single cookie.", EventName = "TempDataCookieSaveFailure")]
+        public static partial void TempDataCookieSaveFailure(ILogger logger, string cookieName);
+    }
+}

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

@@ -1,3 +1,24 @@
 #nullable enable
 Microsoft.AspNetCore.Components.Endpoints.BasePath
 Microsoft.AspNetCore.Components.Endpoints.BasePath.BasePath() -> void
+Microsoft.AspNetCore.Components.Endpoints.TempDataProviderServiceCollectionExtensions
+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.Peek(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData
+Microsoft.AspNetCore.Components.TempData.TempData() -> void
+Microsoft.AspNetCore.Components.TempData.Clear() -> void
+Microsoft.AspNetCore.Components.TempData.this[string! key].get -> object?
+Microsoft.AspNetCore.Components.TempData.this[string! key].set -> void
+Microsoft.AspNetCore.Components.TempData.ContainsKey(string! key) -> bool
+Microsoft.AspNetCore.Components.TempData.ContainsValue(object? value) -> bool
+Microsoft.AspNetCore.Components.TempData.Get(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData.Peek(string! key) -> object?
+Microsoft.AspNetCore.Components.TempData.Keep() -> void
+Microsoft.AspNetCore.Components.TempData.Keep(string! key) -> void
+Microsoft.AspNetCore.Components.TempData.Remove(string! key) -> bool
+Microsoft.AspNetCore.Components.TempData.Load(System.Collections.Generic.IDictionary<string!, object?>! data) -> void
+Microsoft.AspNetCore.Components.TempData.Save() -> System.Collections.Generic.IDictionary<string!, object?>!
+static Microsoft.AspNetCore.Components.Endpoints.TempDataProviderServiceCollectionExtensions.AddTempDataValueProvider(this Microsoft.Extensions.DependencyInjection.IServiceCollection! services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection!

src/Components/Endpoints/src/TempData/ITempData.cs

@@ -0,0 +1,32 @@
+// 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 : IDictionary<string, object?>
+{
+    /// <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);
+}