Ability to use IFormFile or IFormFileCollection in HTTP middleware. C…

src/Http/Wolverine.Http.Tests/Bugs/Bug_926_form_file_used_by_middleware.cs

@@ -0,0 +1,86 @@
+using Alba;
+using IntegrationTests;
+using Marten;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.Extensions.Options;
+using Wolverine.Attributes;
+using Wolverine.Marten;
+
+namespace Wolverine.Http.Tests.Bugs;
+
+public class Bug_926_form_file_used_by_middleware
+{
+    [Fact]
+    public async Task should_only_codegen_the_form_file_once()
+    {
+        var builder = WebApplication.CreateBuilder([]);
+
+        builder.Services.AddMarten(opts =>
+        {
+            // Establish the connection string to your Marten database
+            opts.Connection(Servers.PostgresConnectionString);
+            opts.DatabaseSchemaName = "myapp";
+
+            // Specify that we want to use STJ as our serializer
+            opts.UseSystemTextJsonForSerialization();
+
+            opts.Policies.AllDocumentsSoftDeleted();
+            opts.Policies.AllDocumentsAreMultiTenanted();
+
+            opts.DisableNpgsqlLogging = true;
+        }).IntegrateWithWolverine();
+
+        builder.Host.UseWolverine(opts =>
+        {
+            opts.Discovery.DisableConventionalDiscovery();
+            opts.ApplicationAssembly = GetType().Assembly;
+        });
+
+        // This is using Alba, which uses WebApplicationFactory under the covers
+        await using var host = await AlbaHost.For(builder, app =>
+        {
+            app.MapWolverineEndpoints();
+        });
+
+        await host.Scenario(x =>
+        {
+            x.Post.Url("/api/files/upload").ContentType("application/x-www-form-urlencoded");
+
+
+        });
+    }
+}
+
+public static class FileUploadEndpoint
+{
+    [Middleware(
+        typeof(FileLengthValidationMiddleware), 
+        typeof(FileExtensionValidationMiddleware)
+    )]
+    [WolverinePost("/api/files/upload")]
+    public static async Task<Ok> HandleAsync(IFormFile file)
+    {
+        // todo, generate filename, write mapping to table
+        // todo, create sideeffect to write file with new filename
+
+        return TypedResults.Ok(); // return new filename
+    }
+}
+
+public static class FileLengthValidationMiddleware
+{
+    public static void Before(IFormFile file)
+    {
+        // todo, return ProblemDetail if validation fails
+    }
+}
+
+public static class FileExtensionValidationMiddleware
+{
+    public static void Before(IFormFile file)
+    {
+        // todo, return ProblemDetail if validation fails
+    }
+}

src/Http/Wolverine.Http/CodeGen/FromFileStrategy.cs

@@ -19,19 +19,40 @@ public bool TryMatch(HttpChain chain, IContainer container, ParameterInfo parame
         {
             chain.FileParameters.Add(parameter);
 
+            var existing = chain.ChainVariables.FirstOrDefault(x => x.VariableType == typeof(IFormFile));
+            if (existing != null)
+            {
+                variable = existing;
+                return true;
+            }
+
             var frame = new FromFileValue(parameter);
-                chain.Middleware.Add(frame);
-                variable = frame.Variable;
+            chain.Middleware.Add(frame);
+            variable = frame.Variable;
+            chain.ChainVariables.Add(variable);
+
             return true;
-        } else if (parameter.ParameterType == typeof(IFormFileCollection))
+        }
+
+        if (parameter.ParameterType == typeof(IFormFileCollection))
         {
             chain.FileParameters.Add(parameter);
 
+            var existing = chain.ChainVariables.FirstOrDefault(x => x.VariableType == typeof(IFormFileCollection));
+            if (existing != null)
+            {
+                variable = existing;
+                return true;
+            }
+
             var frame = new FromFileValues(parameter);
-                chain.Middleware.Add(frame);
-                variable = frame.Variable;
+            chain.Middleware.Add(frame);
+            variable = frame.Variable;
+            chain.ChainVariables.Add(variable);
+
             return true;
         }
+
         variable = null;
         return false;
     }

src/Http/Wolverine.Http/HttpChain.Codegen.cs

@@ -2,6 +2,7 @@
 using System.Reflection;
 using JasperFx.CodeGeneration;
 using JasperFx.CodeGeneration.Frames;
+using JasperFx.CodeGeneration.Model;
 using JasperFx.Core;
 using JasperFx.Core.Reflection;
 using Microsoft.AspNetCore.Http;
@@ -17,6 +18,13 @@ namespace Wolverine.Http;
 
 public partial class HttpChain
 {
+    /// <summary>
+    /// Used to cache variables like for IFormFile or IFormFileCollection
+    /// that might be reused between middleware and handler methods, but should
+    /// not be created more than once
+    /// </summary>
+    public List<Variable> ChainVariables { get; } = new();
+
     internal string? SourceCode => _generatedType?.SourceCode;
 
     private readonly object _locker = new();