API Patterns

Name: api-patterns
Rating: 65
Author: tridentsof

RESTful API design for ASP.NET Core.

REST Conventions

Method	Action	Route	Response
GET	List	/api/users	200 + array
GET	Read	/api/users/{id}	200 or 404
POST	Create	/api/users	201 + object
PUT	Update	/api/users/{id}	200 or 404
DELETE	Delete	/api/users/{id}	204 or 404

Response Format

csharp

public class ApiResponse<T>
{
    public bool Success { get; set; }
    public T? Data { get; set; }
    public string? Error { get; set; }
    public List<string>? Errors { get; set; }
}

Pagination

csharp

[HttpGet]
public async Task<ActionResult<PagedResult<UserDto>>> GetUsers(
    [FromQuery] int page = 1,
    [FromQuery] int pageSize = 20)
{
    var result = await _service.GetPagedAsync(page, pageSize);
    return Ok(result);
}

public class PagedResult<T>
{
    public List<T> Items { get; set; }
    public int TotalCount { get; set; }
    public int Page { get; set; }
    public int PageSize { get; set; }
}

Validation

csharp

public class CreateUserDto
{
    [Required]
    [EmailAddress]
    public string Email { get; set; }
    
    [Required]
    [StringLength(100, MinimumLength = 2)]
    public string Name { get; set; }
}

Error Handling

csharp

// Global exception handler
app.UseExceptionHandler(app =>
{
    app.Run(async context =>
    {
        context.Response.StatusCode = 500;
        await context.Response.WriteAsJsonAsync(new ApiResponse<object>
        {
            Success = false,
            Error = "An error occurred"
        });
    });
});

Versioning

csharp

[ApiController]
[Route("api/v{version:apiVersion}/[controller]")]
[ApiVersion("1.0")]
public class UsersController : ControllerBase

DO / DON'T

✅ Do	❌ Don't
Consistent responses	Mixed formats
Proper status codes	200 for everything
Validate input	Trust user data
Version APIs	Breaking changes