support for SmartEnum Model binding in razor pages, fixes #70 (#210)

Co-authored-by: Steve Smith <steve@kentsmiths.com>

SmartEnum.ModelBinding/SmartEnum.ModelBinding.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net5</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Core" Version="2.2.5" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\src\SmartEnum\SmartEnum.csproj" />
+  </ItemGroup>
+
+</Project>

SmartEnum.ModelBinding/SmartEnumBinderProvider.cs

@@ -0,0 +1,20 @@
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.ModelBinding.Binders;
+using System;
+
+namespace Ardalis.SmartEnum.ModelBinding
+{
+    public class SmartEnumBinderProvider : IModelBinderProvider
+    {
+        public IModelBinder GetBinder(ModelBinderProviderContext context)
+        {
+            if (context == null)
+                throw new ArgumentNullException(nameof(context));
+
+            if (TypeUtil.IsDerived(context.Metadata.ModelType, typeof(SmartEnum<,>)))
+                return new BinderTypeModelBinder(typeof(SmartEnumModelBinder));
+
+            return null;
+        }
+    }
+}

SmartEnum.ModelBinding/SmartEnumModelBinder.cs

@@ -0,0 +1,54 @@
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using System;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace Ardalis.SmartEnum.ModelBinding
+{
+    public class SmartEnumModelBinder : IModelBinder
+    {
+        public Task BindModelAsync(ModelBindingContext bindingContext)
+        {
+            if (bindingContext == null)
+                throw new ArgumentNullException(nameof(bindingContext));
+
+            Type modelType = bindingContext.ModelMetadata.ModelType;
+
+            if (!TypeUtil.IsDerived(modelType, typeof(SmartEnum<,>)))
+                throw new ArgumentException($"{modelType} is not a SmartEnum");
+
+            string propertyName = bindingContext.ModelName;
+            ValueProviderResult valueProviderResult = bindingContext.ValueProvider.GetValue(propertyName);
+            if (valueProviderResult == ValueProviderResult.None)
+                return Task.CompletedTask;
+
+            bindingContext.ModelState.SetModelValue(propertyName, valueProviderResult);
+
+            string enumKeyName = valueProviderResult.FirstValue;
+
+            if (string.IsNullOrEmpty(enumKeyName))
+                return Task.CompletedTask;
+
+            // Create smart enum instance from enum key name by calling the FromName static method on the SmartEnum Class
+            Type baseSmartEnumType = TypeUtil.GetTypeFromGenericType(modelType, typeof(SmartEnum<,>));
+            foreach (MethodInfo methodInfo in baseSmartEnumType.GetMethods())
+            {
+                if (methodInfo.Name == "FromName")
+                {
+                    ParameterInfo[] methodsParams = methodInfo.GetParameters();
+                    if (methodsParams.Length == 2)
+                    {
+                        if (methodsParams[0].ParameterType == typeof(string) && methodsParams[1].ParameterType == typeof(bool))
+                        {
+                            var enumObj = methodInfo.Invoke(null, new object[] { enumKeyName, true });
+                            bindingContext.Result = ModelBindingResult.Success(enumObj);
+                            return Task.CompletedTask;
+                        }
+                    }
+                }
+            }
+            bindingContext.ModelState.TryAddModelError(propertyName, $"unable to call FromName on the SmartEnum of type {modelType}");
+            return Task.CompletedTask;
+        }
+    }
+}

SmartEnum.ModelBinding/TypeUtil.cs

@@ -0,0 +1,47 @@
+using System;
+
+namespace Ardalis.SmartEnum.ModelBinding
+{
+    internal static class TypeUtil
+    {
+        public static bool IsDerived(Type objectType, Type mainType)
+        {
+            Type currentType = objectType.BaseType;
+
+            if (currentType == null)
+            {
+                return false;
+            }
+
+            while (currentType != typeof(object))
+            {
+                if (currentType.IsGenericType && currentType.GetGenericTypeDefinition() == mainType)
+                    return true;
+
+                currentType = currentType.BaseType;
+            }
+
+            return false;
+        }
+
+        public static Type GetTypeFromGenericType(Type objectType, Type mainType)
+        {
+            Type currentType = objectType.BaseType;
+
+            if (currentType == null)
+            {
+                return null;
+            }
+
+            while (currentType != typeof(object))
+            {
+                if (currentType.IsGenericType && currentType.GetGenericTypeDefinition() == mainType)
+                    return currentType;
+
+                currentType = currentType.BaseType;
+            }
+
+            return null;
+        }
+    }
+}

SmartEnum.sln

@@ -60,6 +60,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SmartEnum.EFCore.Integratio
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "IntegrationTests", "IntegrationTests", "{EF5634F4-4667-4481-934C-D1CFA042AD0B}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SmartEnum.ModelBinding", "SmartEnum.ModelBinding\SmartEnum.ModelBinding.csproj", "{299BCE09-6CA5-4E07-AD55-F3C8AAB30155}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -134,6 +136,10 @@ Global
 		{DF5E3B19-AE8E-48A4-B023-4FA42D6EA8FF}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{DF5E3B19-AE8E-48A4-B023-4FA42D6EA8FF}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{DF5E3B19-AE8E-48A4-B023-4FA42D6EA8FF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{299BCE09-6CA5-4E07-AD55-F3C8AAB30155}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{299BCE09-6CA5-4E07-AD55-F3C8AAB30155}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{299BCE09-6CA5-4E07-AD55-F3C8AAB30155}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{299BCE09-6CA5-4E07-AD55-F3C8AAB30155}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -157,6 +163,7 @@ Global
 		{CDA8EF6E-F678-4FD3-80B0-5C61FC76EE51} = {FA199ECB-5F29-442A-AAC6-91DBCB7A5A04}
 		{DF5E3B19-AE8E-48A4-B023-4FA42D6EA8FF} = {EF5634F4-4667-4481-934C-D1CFA042AD0B}
 		{EF5634F4-4667-4481-934C-D1CFA042AD0B} = {79268877-BBEF-4DE2-B8D9-697F21933159}
+		{299BCE09-6CA5-4E07-AD55-F3C8AAB30155} = {FA199ECB-5F29-442A-AAC6-91DBCB7A5A04}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {46896DE3-41B8-442F-A6FB-6AC9F11CCBCE}