Added string arrays to simple binding (dotnet#63072)

* Added string arrays to simple binding

* Added unit test for handling string array from form parameter

* Updated test with HttpContext check

* ParameterBindingMetadata check returned

---------

Co-authored-by: StickFun <2000stickfun@gmail.com>

Author: StickFun

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

@@ -129,6 +129,7 @@ public static partial class RequestDelegateFactory
     private static readonly string[] FormFileContentType = new[] { "multipart/form-data" };
     private static readonly string[] FormContentType = new[] { "multipart/form-data", "application/x-www-form-urlencoded" };
     private static readonly string[] PlaintextContentType = new[] { "text/plain" };
+    private static readonly Type[] StringTypes = new[] {typeof(string), typeof(StringValues), typeof(StringValues?) };
 
     /// <summary>
     /// Returns metadata inferred automatically for the <see cref="RequestDelegate"/> created by <see cref="Create(Delegate, RequestDelegateFactoryOptions?, RequestDelegateMetadataResult?)"/>.
@@ -791,11 +792,11 @@ private static Expression CreateArgument(ParameterInfo parameter, RequestDelegat
             // For complex types, leverage the shared form binding infrastructure. For example,
             // shared form binding does not currently only supports types that implement IParsable
             // while RDF's binding implementation supports all TryParse implementations.
-            var useSimpleBinding = parameter.ParameterType == typeof(string) ||
-                parameter.ParameterType == typeof(StringValues) ||
-                parameter.ParameterType == typeof(StringValues?) ||
+            var useSimpleBinding = StringTypes.Contains(parameter.ParameterType) ||
                 ParameterBindingMethodCache.Instance.HasTryParseMethod(parameter.ParameterType) ||
-                (parameter.ParameterType.IsArray && ParameterBindingMethodCache.Instance.HasTryParseMethod(parameter.ParameterType.GetElementType()!));
+                (parameter.ParameterType.IsArray &&
+                (StringTypes.Contains(parameter.ParameterType.GetElementType()) ||
+                ParameterBindingMethodCache.Instance.HasTryParseMethod(parameter.ParameterType.GetElementType()!)));
             hasTryParse = useSimpleBinding;
             return useSimpleBinding
                 ? BindParameterFromFormItem(parameter, formAttribute.Name ?? parameter.Name, factoryContext)

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

@@ -684,6 +684,34 @@ public async Task RequestDelegateHandlesNullableStringValuesFromExplicitQueryStr
         Assert.Null(httpContext.Items["form"]);
     }
 
+    [Fact]
+    public async Task RequestDelegateHandlesFromFormStringArrayParameter()
+    {
+        var httpContext = CreateHttpContext();
+        httpContext.Request.Form = new FormCollection(new Dictionary<string, StringValues>
+        {
+            ["form"] = new(new[] { "1", "2", "3" })
+        });
+
+        var factoryResult = RequestDelegateFactory.Create(
+            (HttpContext context, [FromForm(Name = "form")] string[] formValues) =>
+        {
+            context.Items["form"] = formValues;
+        });
+
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        await requestDelegate(httpContext);
+
+        var parameterBindingMetadata = factoryResult.EndpointMetadata
+            .FirstOrDefault(e => e is ParameterBindingMetadata metadata &&
+                metadata.Name == "formValues") as ParameterBindingMetadata;
+
+        Assert.NotNull(parameterBindingMetadata);
+        Assert.Equal(typeof(string[]), parameterBindingMetadata.ParameterInfo.ParameterType);
+        Assert.Equal(new StringValues(new[] { "1", "2", "3" }), httpContext.Items["form"]!);
+    }
+
     [Fact]
     public async Task RequestDelegateCanAwaitValueTasksThatAreNotImmediatelyCompleted()
     {