Add Feature

Step 2: Create Handler

public sealed class Create{Entity}Handler(
    IRepository<{Entity}> repository,
    ICurrentUser currentUser) : ICommandHandler<Create{Entity}Command, Create{Entity}Response>
{
    public async ValueTask<Create{Entity}Response> Handle(
        Create{Entity}Command command,
        CancellationToken ct)
    {
        var entity = {Entity}.Create(command.Name, command.Price, currentUser.TenantId);
        await repository.AddAsync(entity, ct);
        return new Create{Entity}Response(entity.Id);
    }
}

Step 3: Create Validator (Commands Only)

public sealed class Create{Entity}Validator : AbstractValidator<Create{Entity}Command>
{
    public Create{Entity}Validator()
    {
        RuleFor(x => x.Name).NotEmpty().MaximumLength(200);
        RuleFor(x => x.Price).GreaterThan(0);
    }
}

Step 4: Create Endpoint

public static class Create{Entity}Endpoint
{
    public static RouteHandlerBuilder Map(this IEndpointRouteBuilder endpoints) =>
        endpoints.MapPost("/", async (
            Create{Entity}Command command,
            IMediator mediator,
            CancellationToken ct) => TypedResults.Created(
                $"/{entities}/{(await mediator.Send(command, ct)).Id}"))
        .WithName(nameof(Create{Entity}Command))
        .WithSummary("Create a new {entity}")
        .RequirePermission({Module}Permissions.{Entities}.Create);
}

Step 5: Add DTOs to Contracts

In src/Modules/{Module}/Modules.{Module}.Contracts/:

public sealed record Create{Entity}Response(Guid Id);
public sealed record {Entity}Dto(Guid Id, string Name, decimal Price);

Step 6: Wire Endpoint in Module

In {Module}Module.cs MapEndpoints method:

var entities = endpoints.MapGroup("/{entities}").WithTags("{Entities}");
entities.Map{Action}{Entity}Endpoint();

Step 7: Verify

dotnet build src/FSH.Starter.slnx  # Must be 0 warnings
dotnet test src/FSH.Starter.slnx

Checklist

• Command/Query uses ICommand<T> or IQuery<T> (NOT MediatR's IRequest)
• Handler uses ICommandHandler<T,R> or IQueryHandler<T,R>
• Handler returns ValueTask<T> (NOT Task<T>)
• Validator exists for commands
• Endpoint has .RequirePermission() or .AllowAnonymous()
• Endpoint has .WithName() and .WithSummary()
• DTOs in Contracts project, not internal
• Build passes with 0 warnings