Add tests and fix exception handling in form binding (#49983)

Author: captainsafia

src/Components/Endpoints/src/FormMapping/FormDataReader.cs

@@ -73,6 +73,13 @@ public void AddMappingError(Exception exception, string? attemptedValue)
     {
         ArgumentNullException.ThrowIfNull(exception);
 
+        // Avoid re-wrapping the exception if it is already a FormDataMappingException
+        // and we don't have an ErrorHandler configured.
+        if (exception is FormDataMappingException && ErrorHandler == null)
+        {
+            throw exception;
+        }
+
         var errorMessage = FormattableStringFactory.Create(exception.Message);
         AddMappingError(errorMessage, attemptedValue);
     }
@@ -183,7 +190,7 @@ internal void PopPrefix(ReadOnlySpan<char> key)
         _currentDepth--;
         Debug.Assert(_currentDepth >= 0);
         var keyLength = key.Length;
-        // If keyLength is bigger than the current scope keyLength typically means there is a 
+        // If keyLength is bigger than the current scope keyLength typically means there is a
         // bug where some part of the code has not popped the scope appropriately.
         Debug.Assert(_currentPrefixBuffer.Length >= keyLength);
         if (_currentPrefixBuffer.Length == keyLength || _currentPrefixBuffer.Span[^(keyLength + 1)] != '.')

src/Http/Http.Extensions/src/RequestDelegateFactory.cs

@@ -2039,6 +2039,10 @@ private static Expression BindComplexParameterFromFormItem(
                 formDict,
                 Expression.Constant(CultureInfo.InvariantCulture),
                 Expression.Call(AsMemoryMethod, formBuffer, Expression.Constant(0), Expression.Constant(formDataMapperOptions.MaxKeyBufferSize))));
+        // name_reader.MaxRecursionDepth = formDataMapperOptions.MaxRecursionDepth;
+        var setMaxRecursionDepthExpr = Expression.Assign(
+            Expression.Property(formReader, nameof(FormDataReader.MaxRecursionDepth)),
+            Expression.Constant(formDataMapperOptions.MaxRecursionDepth));
         // FormDataMapper.Map<string>(name_reader, FormDataMapperOptions);
         var invokeMapMethodExpr = Expression.Call(
             FormDataMapperMapMethod.MakeGenericMethod(parameter.ParameterType),
@@ -2063,6 +2067,7 @@ private static Expression BindComplexParameterFromFormItem(
                 Expression.Block(
                     processFormExpr,
                     initializeReaderExpr,
+                    setMaxRecursionDepthExpr,
                     Expression.Assign(formArgument, invokeMapMethodExpr)),
                 conditionalReturnBufferExpr),
             formArgument

src/Http/Http.Extensions/test/RequestDelegateFactoryTests.FormMapping.cs

@@ -167,6 +167,122 @@ static void TestAction([FromForm] Dictionary<string, string> args) { }
 
         // Assert - 2
         Assert.Equal("Specified argument was out of the range of valid values.", anotherException.Message);
+    }
+
+    [Fact]
+    public async Task SupportsFormMappingWithRecordTypes()
+    {
+        TodoRecord capturedTodo = default;
+        void TestAction([FromForm] TodoRecord args) { capturedTodo = args; };
+        var httpContext = CreateHttpContext();
+        httpContext.Request.Form = new FormCollection(new Dictionary<string, StringValues>
+        {
+            {
+                "id", "1"
+            },
+            {
+                "name", "Write tests"
+            },
+            {
+                "isCompleted", "false"
+            }
+        });
+
+        var factoryResult = RequestDelegateFactory.Create(TestAction);
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        await requestDelegate(httpContext);
+
+        Assert.Equal(StatusCodes.Status200OK, httpContext.Response.StatusCode);
+        Assert.Equal(1, capturedTodo.Id);
+        Assert.Equal("Write tests", capturedTodo.Name);
+        Assert.False(capturedTodo.IsCompleted);
+    }
+
+    [Fact]
+    public async Task SupportsRecursiveProperties()
+    {
+        Employee capturedEmployee = default;
+        void TestAction([FromForm] Employee args) { capturedEmployee = args; };
+        var httpContext = CreateHttpContext();
+        httpContext.Request.Form = new FormCollection(new Dictionary<string, StringValues>
+        {
+            {
+                "Name", "A"
+            },
+            {
+                "Manager.Name", "B"
+            },
+            {
+                "Manager.Manager.Name", "C"
+            },
+            {
+                "Manager.Manager.Manager.Name", "D"
+            }
+        });
+
+        var factoryResult = RequestDelegateFactory.Create(TestAction);
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        await requestDelegate(httpContext);
+
+        Assert.Equal(StatusCodes.Status200OK, httpContext.Response.StatusCode);
+    }
 
+    [Fact]
+    public async Task SupportsRecursivePropertiesWithRecursionLimit()
+    {
+        Employee capturedEmployee = default;
+        var options = new RequestDelegateFactoryOptions
+        {
+            EndpointBuilder = CreateEndpointBuilder(new List<object>()
+            {
+                new FormMappingOptionsMetadata(maxRecursionDepth: 3)
+            }),
+        };
+        var metadataResult = new RequestDelegateMetadataResult { EndpointMetadata = new List<object>() };
+        void TestAction([FromForm] Employee args) { capturedEmployee = args; };
+        var httpContext = CreateHttpContext();
+        httpContext.Request.Form = new FormCollection(new Dictionary<string, StringValues>
+        {
+            {
+                "Name", "A"
+            },
+            {
+                "Manager.Name", "B"
+            },
+            {
+                "Manager.Manager.Name", "C"
+            },
+            {
+                "Manager.Manager.Manager.Name", "D"
+            },
+            {
+                "Manager.Manager.Manager.Manager.Name", "E"
+            },
+            {
+                "Manager.Manager.Manager.Manager.Manager.Name", "F"
+            },
+            {
+                "Manager.Manager.Manager.Manager.Manager.Manager.Name", "G"
+            }
+        });
+
+        var factoryResult = RequestDelegateFactory.Create(TestAction, options, metadataResult);
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        var exception = await Assert.ThrowsAsync<FormDataMappingException>(async () => await requestDelegate(httpContext));
+
+        Assert.Equal("Manager.Manager.Manager", exception.Error.Key);
+        Assert.Equal("The maximum recursion depth of '3' was exceeded for 'Manager.Manager.Manager.Name'.", exception.Error.Message.ToString(CultureInfo.InvariantCulture));
+
+    }
+
+    private record TodoRecord(int Id, string Name, bool IsCompleted);
+
+    private class Employee
+    {
+        public string Name { get; set; }
+        public Employee Manager { get; set; }
     }
 }