Add support for external class validators

Directory.Packages.props

@@ -13,5 +13,6 @@
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.13.12" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.0" />
   </ItemGroup>
 </Project>

README.md

@@ -41,8 +41,11 @@ class Widget
 var widget = new Widget { Name = "" };
 
 // Get your serviceProvider from wherever makes sense
-var serviceProvider = ...
-var isValid = MiniValidator.TryValidate(widget, serviceProvider, out var errors);
+var services = new ServicesCollection();
+services.AddMiniValidation();
+var serviceProvider = services.CreateServiceProvider();
+var validator = serviceProvider.GetRequiredService<IMiniValidator>();
+var isValid = validator.TryValidate(widget, out var errors);
 
 class Widget : IValidatableObject
 {

samples/Samples.Console/Samples.Console.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 

samples/Samples.Web/Program.cs

@@ -6,6 +6,8 @@
 
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();
+builder.Services.AddMiniValidator();
+builder.Services.AddClassMiniValidator<WidgetValidator>();
 
 var app = builder.Build();
 
@@ -23,15 +25,36 @@
 app.MapGet("/widgets/{name}", (string name) =>
     new Widget { Name = name });
 
-app.MapPost("/widgets", Results<ValidationProblem, Created<Widget>> (Widget widget) =>
-    !MiniValidator.TryValidate(widget, out var errors)
-        ? TypedResults.ValidationProblem(errors)
-        : TypedResults.Created($"/widgets/{widget.Name}", widget));
+app.MapPost("/widgets", Results<ValidationProblem, Created<Widget>> (Widget widget, IMiniValidator validator) =>
+{
+    if (!validator.TryValidate(widget, out var errors))
+    {
+        return TypedResults.ValidationProblem(errors);
+    }
+
+    return TypedResults.Created($"/widgets/{widget.Name}", widget);
+});
+
+app.MapPost("/widgets/class-validator", async Task<Results<ValidationProblem, Created<WidgetWithClassValidator>>> (WidgetWithClassValidator widget, IMiniValidator<WidgetWithClassValidator> validator) =>
+{
+    var (isValid, errors) = await validator.TryValidateAsync(widget);
+    if (!isValid)
+    {
+        return TypedResults.ValidationProblem(errors);
+    }
 
-app.MapPost("/widgets/custom-validation", Results<ValidationProblem, Created<WidgetWithCustomValidation>> (WidgetWithCustomValidation widget) =>
-    !MiniValidator.TryValidate(widget, out var errors)
-        ? TypedResults.ValidationProblem(errors)
-        : TypedResults.Created($"/widgets/{widget.Name}", widget));
+    return TypedResults.Created($"/widgets/{widget.Name}", widget);
+});
+
+app.MapPost("/widgets/custom-validation", Results<ValidationProblem, Created<WidgetWithCustomValidation>> (WidgetWithCustomValidation widget, IMiniValidator<WidgetWithCustomValidation> validator) =>
+{
+    if (!validator.TryValidate(widget, out var errors))
+    {
+        return TypedResults.ValidationProblem(errors);
+    }
+
+    return TypedResults.Created($"/widgets/{widget.Name}", widget);
+});
 
 app.Run();
 
@@ -43,13 +66,34 @@ class Widget
     public override string? ToString() => Name;
 }
 
+class WidgetWithClassValidator : Widget
+{
+    [Required, MinLength(3), Display(Name = "Widget name")]
+    public string? Name { get; set; }
+
+    public override string? ToString() => Name;
+}
+
 class WidgetWithCustomValidation : Widget, IValidatableObject
 {
     public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
     {
         if (string.Equals(Name, "Widget", StringComparison.OrdinalIgnoreCase))
         {
-            yield return new($"Cannot name a widget '{Name}'.", new[] { nameof(Name) });
+            yield return new($"Cannot name a widget '{Name}'.", [nameof(Name)]);
+        }
+    }
+}
+
+class WidgetValidator : IValidate<WidgetWithClassValidator>
+{
+    public IEnumerable<ValidationResult> Validate(WidgetWithClassValidator instance, ValidationContext validationContext)
+    {
+        if (string.Equals(instance.Name, "Widget", StringComparison.OrdinalIgnoreCase))
+        {
+            return [new($"Cannot name a widget '{instance.Name}'.", [nameof(instance.Name)])];
         }
+
+        return [];
     }
 }

samples/Samples.Web/Samples.Web.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>

src/MiniValidation/IAsyncValidatableObject.cs

@@ -14,5 +14,9 @@ public interface IAsyncValidatableObject
     /// </summary>
     /// <param name="validationContext">The validation context.</param>
     /// <returns>A collection that holds failed-validation information.</returns>
+#if NET6_0_OR_GREATER
+    ValueTask<IEnumerable<ValidationResult>> ValidateAsync(ValidationContext validationContext);
+#else
     Task<IEnumerable<ValidationResult>> ValidateAsync(ValidationContext validationContext);
+#endif
 }

src/MiniValidation/IAsyncValidate.cs

@@ -0,0 +1,24 @@
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Threading.Tasks;
+
+namespace MiniValidation;
+
+/// <summary>
+/// Provides a way to add a validator for a type outside the class.
+/// </summary>
+/// <typeparam name="T">The type to validate.</typeparam>
+public interface IAsyncValidate<in T>
+{
+    /// <summary>
+    /// Determines whether the specified object is valid.
+    /// </summary>
+    /// <param name="instance">The object instance to validate.</param>
+    /// <param name="validationContext">The validation context.</param>
+    /// <returns>A collection that holds failed-validation information.</returns>
+#if NET6_0_OR_GREATER
+    ValueTask<IEnumerable<ValidationResult>> ValidateAsync(T instance, ValidationContext validationContext);
+#else
+    Task<IEnumerable<ValidationResult>> ValidateAsync(T instance, ValidationContext validationContext);
+#endif
+}

src/MiniValidation/IMiniValidator.cs

@@ -0,0 +1,150 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace MiniValidation;
+
+/// <summary>
+/// Represents a validator that can validate an object.
+/// </summary>
+public interface IMiniValidator
+{
+    /// <summary>
+    /// Determines if the specified <see cref="Type"/> has anything to validate.
+    /// </summary>
+    /// <remarks>
+    /// Objects of types with nothing to validate will always return <c>true</c> when passed to <see cref="TryValidate{TTarget}(TTarget, bool, out IDictionary{string, string[]})"/>.
+    /// </remarks>
+    /// <param name="targetType">The <see cref="Type"/>.</param>
+    /// <param name="recurse"><c>true</c> to recursively check descendant types; if <c>false</c> only simple values directly on the target type are checked.</param>
+    /// <returns><c>true</c> if <paramref name="targetType"/> has anything to validate, <c>false</c> if not.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="targetType"/> is <c>null</c>.</exception>
+    bool RequiresValidation(Type targetType, bool recurse = true);
+
+    /// <summary>
+    /// Determines whether the specific object is valid. This method recursively validates descendant objects.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    bool TryValidate<TTarget>(TTarget target, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <typeparam name="TTarget">The type of the target of validation.</typeparam>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    bool TryValidate<TTarget>(TTarget target, bool recurse, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <typeparam name="TTarget"></typeparam>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <param name="allowAsync"><c>true</c> to allow asynchronous validation if an object in the graph requires it.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    /// <exception cref="ArgumentException">Throw when <paramref name="target"/> requires async validation and <paramref name="allowAsync"/> is <c>false</c>.</exception>
+    bool TryValidate<TTarget>(TTarget target, bool recurse, bool allowAsync, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+#if NET6_0_OR_GREATER
+    ValueTask<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync<TTarget>(TTarget target);
+#else
+    Task<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync<TTarget>(TTarget target);
+#endif
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c> and the validation errors.</returns>
+    /// <exception cref="ArgumentNullException"></exception>
+#if NET6_0_OR_GREATER
+    ValueTask<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync<TTarget>(TTarget target, bool recurse);
+#else
+    Task<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync<TTarget>(TTarget target, bool recurse);
+#endif
+
+    /// <summary>
+    /// Gets a validator for the specified target type.
+    /// </summary>
+    /// <typeparam name="TTarget"></typeparam>
+    /// <returns></returns>
+    IMiniValidator<TTarget> GetValidator<TTarget>();
+}
+
+/// <summary>
+/// Represents a validator that can validate an object of type <typeparamref name="T"/>.
+/// </summary>
+/// <typeparam name="T"></typeparam>
+public interface IMiniValidator<in T>
+{
+
+    /// <summary>
+    /// Determines whether the specific object is valid. This method recursively validates descendant objects.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    bool TryValidate(T target, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    bool TryValidate(T target, bool recurse, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <param name="allowAsync"><c>true</c> to allow asynchronous validation if an object in the graph requires it.</param>
+    /// <param name="errors">A dictionary that contains details of each failed validation.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c>.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+    /// <exception cref="ArgumentException">Throw when <paramref name="target"/> requires async validation and <paramref name="allowAsync"/> is <c>false</c>.</exception>
+    bool TryValidate(T target, bool recurse, bool allowAsync, out IDictionary<string, string[]> errors);
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="target"/> is <c>null</c>.</exception>
+#if NET6_0_OR_GREATER
+    ValueTask<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync(T target);
+#else
+    Task<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync(T target);
+#endif
+
+    /// <summary>
+    /// Determines whether the specific object is valid.
+    /// </summary>
+    /// <param name="target">The object to validate.</param>
+    /// <param name="recurse"><c>true</c> to recursively validate descendant objects; if <c>false</c> only simple values directly on <paramref name="target"/> are validated.</param>
+    /// <returns><c>true</c> if <paramref name="target"/> is valid; otherwise <c>false</c> and the validation errors.</returns>
+    /// <exception cref="ArgumentNullException"></exception>
+#if NET6_0_OR_GREATER
+    ValueTask<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync(T target, bool recurse);
+#else
+    Task<(bool IsValid, IDictionary<string, string[]> Errors)> TryValidateAsync(T target, bool recurse);
+#endif
+}

src/MiniValidation/IValidate.cs

@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+
+namespace MiniValidation;
+
+/// <summary>
+/// Provides a way to add a validator for a type outside the class.
+/// </summary>
+/// <typeparam name="T">The type to validate.</typeparam>
+public interface IValidate<in T>
+{
+    /// <summary>
+    /// Determines whether the specified object is valid.
+    /// </summary>
+    /// <param name="instance">The object instance to validate.</param>
+    /// <param name="validationContext">The validation context.</param>
+    /// <returns>A collection that holds failed-validation information.</returns>
+    IEnumerable<ValidationResult> Validate(T instance, ValidationContext validationContext);
+}