Add the Post Endpoint

Create the DTO Model

In the Models folder add a new file called CreateTaskDto.cs

namespace CrudAppAPI.Models;

public class CreateTaskDto
{
    public string Title { get; set; } = default!;
    public string? Description { get; set; }
    public DateTime? DueDate { get; set; }
    public bool Completed { get; set; } = false;
}

Add Validation for the DTO

Create a new folder called Validators, and a new file called CreateTaskDtoValidator.cs

using CrudAppAPIV2.Models;
using FluentValidation;

namespace CrudAppAPIV2.Validators;

public class CreateTaskDtoValidator: AbstractValidator<CreateTaskDto>
{
    public CreateTaskDtoValidator()
    {
        RuleFor(x => x.Title)
            .NotEmpty()
            .MaximumLength(100);

        RuleFor(x => x.Description)
            .MaximumLength(255);

        RuleFor(x => x.DueDate)
            .GreaterThanOrEqualTo(DateTime.Today)
            .When(x => x.DueDate.HasValue);
    }
}

builder.Services.AddFluentValidationAutoValidation();
builder.Services.AddValidatorsFromAssemblyContaining<CreateTaskDtoValidator>();

Add the Service Method

In the TaskServices.cs file add a method called AddTaskAsync

public async Task AddTaskAsync(CreateTaskDto dto)
{
    using var conn = await _connectionFactory.CreateConnectionAsync();

    var parameters = new DynamicParameters();
    parameters.Add("@Title", dto.Title);
    parameters.Add("@Description", dto.Description);
    parameters.Add("@DueDate", dto.DueDate);
    parameters.Add("@Completed", dto.Completed);

    await conn.ExecuteAsync("AddTask", parameters, commandType: CommandType.StoredProcedure);
}

Add the Endpoint

Add the endpoint to the TaskEndpoints.cs file

app.MapPost("/api/tasks", async (CreateTaskDto dto, TaskService service, IValidator<CreateTaskDto> validator) =>
{
    // Validate the DTO using FluentValidation
    var validationResult = await validator.ValidateAsync(dto);

    if (!validationResult.IsValid)
    {
        // If validation fails, return a BadRequest with validation errors
        return Results.BadRequest(validationResult.Errors);
    }

    // If validation passes, proceed with adding the task
    await service.AddTaskAsync(dto);

    // Return a success response
    return Results.Ok();
});

You will need to import the Models with a using statement as we use the one we created as a parameter in this method

Test the Endpoint

Example JSON payload

{
  "title": "Write blog post",
  "description": "Topic: Clean Architecture",
  "dueDate": "2025-07-10",
  "completed": false
}

12 July 2025