[1.x] Add Empty Response & Error Bag Handling

InertiaCore/Extensions/Configure.cs

@@ -7,6 +7,7 @@
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 
 namespace InertiaCore.Extensions;
 
@@ -24,20 +25,52 @@ public static IApplicationBuilder UseInertia(this IApplicationBuilder app)
             Inertia.Version(Vite.GetManifestHash);
         }
 
-        app.Use(async (context, next) =>
+        // Check if TempData services are available for error bag functionality
+        CheckTempDataAvailability(app);
+
+        app.UseMiddleware<Middleware>();
+
+        return app;
+    }
+
+    private static void CheckTempDataAvailability(IApplicationBuilder app)
+    {
+        // Skip warning in test environments
+        var environment = app.ApplicationServices.GetService<Microsoft.AspNetCore.Hosting.IWebHostEnvironment>();
+        if (environment?.EnvironmentName == "Test" ||
+            (environment?.EnvironmentName != "Development" && IsTestEnvironment()))
         {
-            if (context.IsInertiaRequest()
-                && context.Request.Method == "GET"
-                && context.Request.Headers[InertiaHeader.Version] != Inertia.GetVersion())
+            return;
+        }
+
+        try
+        {
+            var tempDataFactory = app.ApplicationServices.GetService<ITempDataDictionaryFactory>();
+            if (tempDataFactory == null)
             {
-                await OnVersionChange(context, app);
-                return;
+                var logger = app.ApplicationServices.GetService<ILogger<IApplicationBuilder>>();
+                logger?.LogWarning("TempData services are not configured. Error bag functionality will be limited. " +
+                                   "Consider adding services.AddSession() and app.UseSession() to enable full error bag support.");
             }
+        }
+        catch (Exception)
+        {
+            // If we can't check for TempData services, that's also a sign they might not be configured
+            var logger = app.ApplicationServices.GetService<ILogger<IApplicationBuilder>>();
+            logger?.LogWarning("Unable to verify TempData configuration. Error bag functionality may be limited. " +
+                               "Ensure services.AddSession() and app.UseSession() are configured for full error bag support.");
+        }
+    }
 
-            await next();
-        });
-
-        return app;
+    private static bool IsTestEnvironment()
+    {
+        // Check if we're running in a test context by looking for common test assemblies
+        var assemblies = AppDomain.CurrentDomain.GetAssemblies();
+        return assemblies.Any(a =>
+            a.FullName?.Contains("nunit", StringComparison.OrdinalIgnoreCase) == true ||
+            a.FullName?.Contains("xunit", StringComparison.OrdinalIgnoreCase) == true ||
+            a.FullName?.Contains("mstest", StringComparison.OrdinalIgnoreCase) == true ||
+            a.FullName?.Contains("testhost", StringComparison.OrdinalIgnoreCase) == true);
     }
 
     public static IServiceCollection AddInertia(this IServiceCollection services,
@@ -64,17 +97,4 @@ public static IServiceCollection AddViteHelper(this IServiceCollection services,
 
         return services;
     }
-
-    private static async Task OnVersionChange(HttpContext context, IApplicationBuilder app)
-    {
-        var tempData = app.ApplicationServices.GetRequiredService<ITempDataDictionaryFactory>()
-            .GetTempData(context);
-
-        if (tempData.Any()) tempData.Keep();
-
-        context.Response.Headers.Override(InertiaHeader.Location, context.RequestedUri());
-        context.Response.StatusCode = (int)HttpStatusCode.Conflict;
-
-        await context.Response.CompleteAsync();
-    }
 }

InertiaCore/Extensions/InertiaExtensions.cs

@@ -3,6 +3,9 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.Extensions.DependencyInjection;
 using System.Text;
 
 namespace InertiaCore.Extensions;
@@ -63,4 +66,133 @@ internal static string MD5(this string s)
 
         return sb.ToString();
     }
+
+    /// <summary>
+    /// Gets the TempData dictionary for the current HTTP context.
+    /// </summary>
+    internal static ITempDataDictionary? GetTempData(this HttpContext context)
+    {
+        try
+        {
+            var tempDataFactory = context.RequestServices?.GetRequiredService<ITempDataDictionaryFactory>();
+            return tempDataFactory?.GetTempData(context);
+        }
+        catch (InvalidOperationException)
+        {
+            // Service provider not available, return null
+            return null;
+        }
+    }
+
+    /// <summary>
+    /// Sets validation errors in TempData for the specified error bag.
+    /// </summary>
+    public static void SetValidationErrors(this ITempDataDictionary tempData, Dictionary<string, string> errors, string bagName = "default")
+    {
+        // Deserialize existing error bags from JSON
+        var errorBags = new Dictionary<string, Dictionary<string, string>>();
+        if (tempData["__ValidationErrors"] is string existingJson && !string.IsNullOrEmpty(existingJson))
+        {
+            try
+            {
+                errorBags = JsonSerializer.Deserialize<Dictionary<string, Dictionary<string, string>>>(existingJson)
+                           ?? new Dictionary<string, Dictionary<string, string>>();
+            }
+            catch (JsonException)
+            {
+                // If deserialization fails, start fresh
+                errorBags = new Dictionary<string, Dictionary<string, string>>();
+            }
+        }
+
+        errorBags[bagName] = errors;
+
+        // Serialize back to JSON for storage
+        tempData["__ValidationErrors"] = JsonSerializer.Serialize(errorBags);
+    }
+
+    /// <summary>
+    /// Sets validation errors in TempData from ModelState for the specified error bag.
+    /// </summary>
+    public static void SetValidationErrors(this ITempDataDictionary tempData, ModelStateDictionary modelState, string bagName = "default")
+    {
+        var errors = modelState.ToDictionary(
+            kvp => kvp.Key,
+            kvp => kvp.Value?.Errors.FirstOrDefault()?.ErrorMessage ?? ""
+        );
+        tempData.SetValidationErrors(errors, bagName);
+    }
+
+    /// <summary>
+    /// Retrieve and clear validation errors from TempData, supporting error bags.
+    /// </summary>
+    public static Dictionary<string, string> GetAndClearValidationErrors(this ITempDataDictionary tempData, HttpRequest request)
+    {
+        var errors = new Dictionary<string, string>();
+
+        if (!tempData.ContainsKey("__ValidationErrors"))
+            return errors;
+
+        // Deserialize from JSON
+        Dictionary<string, Dictionary<string, string>> storedErrors;
+        if (tempData["__ValidationErrors"] is string jsonString && !string.IsNullOrEmpty(jsonString))
+        {
+            try
+            {
+                storedErrors = JsonSerializer.Deserialize<Dictionary<string, Dictionary<string, string>>>(jsonString) ?? new Dictionary<string, Dictionary<string, string>>();
+            }
+            catch (JsonException)
+            {
+                // If deserialization fails, return empty
+                return errors;
+            }
+        }
+        else
+        {
+            return errors;
+        }
+
+        // Check if there's a specific error bag in the request header
+        var errorBag = "default";
+        if (request.Headers.ContainsKey(InertiaHeader.ErrorBag))
+        {
+            errorBag = request.Headers[InertiaHeader.ErrorBag].ToString();
+        }
+
+        // If there's only the default bag and no specific bag requested, return the default bag directly
+        if (storedErrors.Count == 1 && storedErrors.ContainsKey("default") && errorBag == "default")
+        {
+            foreach (var kvp in storedErrors["default"])
+            {
+                errors[kvp.Key] = kvp.Value;
+            }
+        }
+        // If there are multiple bags or a specific bag is requested, return the named bag
+        else if (storedErrors.ContainsKey(errorBag))
+        {
+            foreach (var kvp in storedErrors[errorBag])
+            {
+                errors[kvp.Key] = kvp.Value;
+            }
+        }
+        // If no specific bag and multiple bags exist, return all bags
+        else if (errorBag == "default" && storedErrors.Count > 1)
+        {
+            // Return all error bags as nested structure
+            // This will be handled differently but for now just return default or first available
+            var firstBag = storedErrors.Values.FirstOrDefault();
+            if (firstBag != null)
+            {
+                foreach (var kvp in firstBag)
+                {
+                    errors[kvp.Key] = kvp.Value;
+                }
+            }
+        }
+
+        // Clear the temp data after reading (one-time use)
+        tempData.Remove("__ValidationErrors");
+
+        return errors;
+    }
 }

InertiaCore/Inertia.cs

@@ -13,6 +13,8 @@ public static class Inertia
 
     internal static void UseFactory(IResponseFactory factory) => _factory = factory;
 
+    internal static void ResetFactory() => _factory = default!;
+
     public static Response Render(string component, object? props = null) => _factory.Render(component, props);
 
     public static Task<IHtmlContent> Head(dynamic model) => _factory.Head(model);
@@ -27,6 +29,8 @@ public static class Inertia
 
     public static LocationResult Location(string url) => _factory.Location(url);
 
+    public static BackResult Back(string? fallbackUrl = null) => _factory.Back(fallbackUrl);
+
     public static void Share(string key, object? value) => _factory.Share(key, value);
 
     public static void Share(IDictionary<string, object?> data) => _factory.Share(data);

InertiaCore/Middleware.cs

@@ -0,0 +1,112 @@
+using InertiaCore;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using System.Net;
+using InertiaCore.Utils;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+using InertiaCore.Extensions;
+
+namespace InertiaCore;
+
+public class Middleware
+{
+    private readonly RequestDelegate _next;
+
+    public Middleware(RequestDelegate next)
+    {
+        _next = next;
+    }
+
+    public async Task InvokeAsync(HttpContext context)
+    {
+        if (context.IsInertiaRequest()
+            && context.Request.Method == "GET"
+            && context.Request.Headers[InertiaHeader.Version] != Inertia.GetVersion())
+        {
+            await OnVersionChange(context);
+            return;
+        }
+
+        await _next(context);
+
+        // Handle empty responses for Inertia requests
+        if (context.IsInertiaRequest()
+            && context.Response.StatusCode == 200
+            && await IsEmptyResponse(context))
+        {
+            await OnEmptyResponse(context);
+        }
+    }
+
+    private static async Task OnVersionChange(HttpContext context)
+    {
+        var tempData = context.RequestServices.GetRequiredService<ITempDataDictionaryFactory>()
+            .GetTempData(context);
+
+        if (tempData.Any()) tempData.Keep();
+
+        context.Response.Headers.Override(InertiaHeader.Location, context.RequestedUri());
+        context.Response.StatusCode = (int)HttpStatusCode.Conflict;
+
+        await context.Response.CompleteAsync();
+    }
+
+    private static async Task<bool> IsEmptyResponse(HttpContext context)
+    {
+        // Check if Content-Length is 0 or not set
+        if (context.Response.Headers.ContentLength.HasValue)
+        {
+            return context.Response.Headers.ContentLength.Value == 0;
+        }
+
+        // Check if response body is empty or only whitespace
+        if (context.Response.Body.CanSeek && context.Response.Body.Length >= 0)
+        {
+            var position = context.Response.Body.Position;
+
+            // Check if the stream has any content
+            if (context.Response.Body.Length == 0)
+            {
+                return true;
+            }
+
+            context.Response.Body.Seek(0, SeekOrigin.Begin);
+
+            using var reader = new StreamReader(context.Response.Body, leaveOpen: true);
+            var content = await reader.ReadToEndAsync();
+
+            context.Response.Body.Seek(position, SeekOrigin.Begin);
+
+            return string.IsNullOrWhiteSpace(content);
+        }
+
+        // For non-seekable streams, check if the response body position is still 0
+        // This indicates nothing has been written to the response
+        try
+        {
+            return context.Response.Body.Position == 0;
+        }
+        catch
+        {
+            // If we can't determine, assume it's not empty to be safe
+            return false;
+        }
+    }
+
+    private static async Task OnEmptyResponse(HttpContext context)
+    {
+        // Use Inertia.Back() to redirect back
+        var backResult = Inertia.Back();
+
+        // Determine the redirect URL using the same logic as BackResult
+        var referrer = context.Request.Headers.Referer.ToString();
+        var redirectUrl = !string.IsNullOrEmpty(referrer) ? referrer : "/";
+
+        // Set the appropriate headers and status code for a back redirect
+        context.Response.StatusCode = (int)HttpStatusCode.SeeOther;
+        context.Response.Headers.Override("Location", redirectUrl);
+
+        await context.Response.CompleteAsync();
+    }
+}