switch to fluent validation

Author: jicking

JixMinApi/Features/Todo/Commands/CreateTodoCommand.cs

@@ -1,8 +1,22 @@
-using MediatR;
+using FluentValidation;
+using FluentValidation.Results;
+using MediatR;
 
 namespace JixMinApi.Features.Todo.Commands;
 
-public record CreateTodoCommand(CreateTodoDto input) : IRequest<Result<TodoDto>>;
+public record CreateTodoCommand(string Name, bool IsComplete) : IRequest<Result<TodoDto>>;
+
+public sealed class CreateTodoCommandValidator
+    : AbstractValidator<CreateTodoCommand>
+{
+    public CreateTodoCommandValidator()
+    {
+        RuleFor(command => command.Name)
+            .NotEmpty()
+            .MinimumLength(4)
+            .MaximumLength(24);
+    }
+}
 
 public class CreateTodoCommandHandler : IRequestHandler<CreateTodoCommand, Result<TodoDto>>
 {
@@ -13,16 +27,20 @@ public class CreateTodoCommandHandler : IRequestHandler<CreateTodoCommand, Resul
 
     public async Task<Result<TodoDto>> Handle(CreateTodoCommand request, CancellationToken cancellationToken)
     {
-        // simple inline validation, if needed validate using behaviors https://github.com/jbogard/MediatR/wiki/Behaviors
-        if (string.IsNullOrEmpty(request.input.Name))
+        // fluent validation inside handler, if needed validate on pipeline using behaviors https://github.com/jbogard/MediatR/wiki/Behaviors
+        var validator = new CreateTodoCommandValidator();
+        ValidationResult validationResult = validator.Validate(request);
+
+        if (!validationResult.IsValid)
         {
-            return new Result<TodoDto>([new KeyValuePair<string, string[]>("Name", ["Must not be empty."])]);
+            var errors = validationResult.Errors.Select(e => new KeyValuePair<string, string>(e.PropertyName, e.ErrorMessage));
+            return new Result<TodoDto>(errors);
         }
 
         var todo = new Todo()
         {
-            Name = request.input.Name,
-            IsComplete = request.input.IsComplete,
+            Name = request.Name,
+            IsComplete = request.IsComplete,
             DateCreated = DateTimeOffset.UtcNow,
         };
 

JixMinApi/Features/Todo/Result.cs

@@ -3,39 +3,44 @@
 
 public class Result<T>
 {
-    public bool IsSuccess => (!HasValidationError && !IsError);
+    public bool IsSuccess => !Errors.Any();
     public T? Value { get; init; }
-
-    public bool HasValidationError { get; init; }
-    public IReadOnlyList<KeyValuePair<string, string[]>> ValidationErrors { get; init; } = [];
-
-    public bool IsError { get; init; }
-    public Exception? Exception { get; init; }
-
+    public IReadOnlyList<KeyValuePair<string, string>> Errors { get; init; } = [];
 
     public Result(T value)
     {
         Value = value;
     }
 
-    public Result(IEnumerable<KeyValuePair<string, string[]>> validationErrors)
+    public Result(IEnumerable<KeyValuePair<string, string>> validationErrors)
     {
-        ValidationErrors = validationErrors.ToList();
-        HasValidationError = true;
+        Errors = validationErrors.ToList();
     }
 
     public Result(string field, string validationErrorMessage)
     {
-        List<KeyValuePair<string, string[]>> validationErrors
-            = [new KeyValuePair<string, string[]>(field, [validationErrorMessage])];
-        ValidationErrors = validationErrors;
-        HasValidationError = true;
+        Errors = [new(field, validationErrorMessage)];
     }
+}
 
-    public Result(Exception exception)
+public static class ResultExtensions
+{
+    public static IDictionary<string, string[]> ToErrorDictionary(this IEnumerable<KeyValuePair<string, string>> errors)
     {
-        Exception = exception;
-        IsError = true;
+        Dictionary<string, string[]> result = [];
+
+        foreach (var e in errors)
+        {
+            if (!result.TryGetValue(e.Key, out var messages))
+            {
+                result[e.Key] = [e.Value];
+                continue;
+            }
+
+            var newArray = messages.Concat([e.Value]).ToArray();
+            result[e.Key] = newArray;
+        }
+
+        return result;
     }
 }
-

JixMinApi/Features/Todo/TodoEndpoints.cs

@@ -100,11 +100,11 @@ public static async Task<Results<ValidationProblem, NotFound, Ok<TodoDto>>> GetT
     /// <response code="400">Invalid payload</response>
     public static async Task<Results<Created<TodoDto>, ValidationProblem>> CreateTodoAsync(CreateTodoDto input, IMediator mediator)
     {
-        var result = await mediator.Send(new CreateTodoCommand(input));
+        var result = await mediator.Send(new CreateTodoCommand(input.Name, input.IsComplete));
 
-        if (result.HasValidationError)
+        if (!result.IsSuccess)
         {
-            return TypedResults.ValidationProblem(result.ValidationErrors.ToDictionary());
+            return TypedResults.ValidationProblem(result.Errors.ToErrorDictionary());
         }
 
         var todo = result.Value;

JixMinApi/JixMinApi.csproj

@@ -11,6 +11,8 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="FluentValidation" Version="11.9.0" />
+    <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="11.9.0" />
     <PackageReference Include="MediatR" Version="12.2.0" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.3" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.3" />

JixMinApi/Program.cs

@@ -1,5 +1,7 @@
+using FluentValidation;
 using JixMinApi.Features.Todo;
 using JixMinApi.Shared;
+using Microsoft.AspNetCore.Identity;
 using Microsoft.OpenApi.Models;
 using System.Reflection;
 
@@ -21,14 +23,14 @@
     options.IncludeXmlComments(xmlPath);
 });
 
+builder.Services.AddExceptionHandler<GlobalExceptionHandler>();
+builder.Services.AddProblemDetails();
+
+builder.Services.AddValidatorsFromAssembly(typeof(Program).Assembly);
 builder.Services.AddMediatR(cfg => cfg.RegisterServicesFromAssembly(typeof(Program).Assembly));
 
-// Inject endpoint services
 builder.Services.AddTodoEndpointServices();
 
-builder.Services.AddExceptionHandler<GlobalExceptionHandler>();
-builder.Services.AddProblemDetails();
-
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.
@@ -38,8 +40,12 @@
     app.UseSwaggerUI();
 }
 
-app.UseHttpsRedirection();
-app.UseExceptionHandler();
+if (!app.Environment.IsDevelopment())
+{
+    app.UseHttpsRedirection();
+    app.UseExceptionHandler();
+}
+
 app.UseTodoEndpoints();
 
 app.Run();

JixMinApiTests/Features/Todo/Commands/CreateTodoCommandHandlerTests.cs

@@ -25,12 +25,12 @@ public void CreateTodoCommandHandlerTest()
     public async void HandleTest()
     {
         Setup();
-        var input = new CreateTodoDto("Test", true);
-        var result = await sut.Handle(new CreateTodoCommand(input), default);
+        const string todoName = "test";
+        var result = await sut.Handle(new CreateTodoCommand(todoName, true), default);
 
         Assert.NotNull(result);
         Assert.True(result.IsSuccess);
-        Assert.Equal(input.Name, result.Value.Name);
-        Assert.Equal(input.IsComplete, result.Value.IsComplete);
+        Assert.Equal(todoName, result.Value.Name);
+        Assert.True(result.Value.IsComplete);
     }
 }