封装WEB API Rest结果

Question

I'm building a WEB API, which has many GET methods like these:

    [HttpGet]
    [Authorize]
    [Route("monedas")]
    public IHttpActionResult GetMonedas(string empresaId, string filtro = "")
    {
        IEnumeradorService sectoresService = new MonedasService(empresaId);
        if (!initialValidation.EmpresaPerteneceACliente(empresaId, User))
        {
            return Content(HttpStatusCode.MethodNotAllowed, "La empresa no existe o el cliente no tiene acceso a ella");
        }
        try
        {
            return Ok(sectoresService.Enumerar(filtro));
        }
        catch (QueryFormatException ex)
        {
            return BadRequest(ex.Message);
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(ex);
            return InternalServerError();
        }
    }

    [HttpGet]
    [Authorize]
    [Route("paises")]
    public IHttpActionResult GetPaises(string empresaId, string filtro = "")
    {
        IEnumeradorService sectoresService = new PaisesService(empresaId);
        if (!initialValidation.EmpresaPerteneceACliente(empresaId, User))
        {
            return Content(HttpStatusCode.MethodNotAllowed, "La empresa no existe o el cliente no tiene acceso a ella");
        }
        try
        {
            return Ok(sectoresService.Enumerar(filtro));
        }
        catch (QueryFormatException ex)
        {
            return BadRequest(ex.Message);
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(ex);
            return InternalServerError();
        }
    }

How can I encapsulate this kind of behavior with re-utilizable code?

Answer 1

You can remove all the try/catch statements by creating an ExceptionFilterAttribute :

public class HandleExceptionsFilter : ExceptionFilterAttribute
{
    public override void OnException(HttpActionExecutedContext context)
    {
        if (context.Exception is QueryFormatException)
        {
            context.Response = context.Request.CreateErrorResponse(HttpStatusCode.BadRequest, context.Exception.Message);
            return;
        }

        System.Diagnostics.Debug.WriteLine(context.Exception);
        context.Response = new HttpResponseMessage(HttpStatusCode.InternalServerError);
    }
}

Then add it to your application:

config.Filters.Add(new HandleExceptionsFilter());

This will make your actions look like this:

[HttpGet]
[Authorize]
[Route("monedas")]
public IHttpActionResult GetMonedas(string empresaId, string filtro = "")
{
    IEnumeradorService sectoresService = new MonedasService(empresaId);
    if (!initialValidation.EmpresaPerteneceACliente(empresaId, User))
    {
        return Content(HttpStatusCode.MethodNotAllowed, "La empresa no existe o el cliente no tiene acceso a ella");
    }

    return Ok(sectoresService.Enumerar(filtro));
}

[HttpGet]
[Authorize]
[Route("paises")]
public IHttpActionResult GetPaises(string empresaId, string filtro = "")
{
    IEnumeradorService sectoresService = new PaisesService(empresaId);
    if (!initialValidation.EmpresaPerteneceACliente(empresaId, User))
    {
        return Content(HttpStatusCode.MethodNotAllowed, "La empresa no existe o el cliente no tiene acceso a ella");
    }

    return Ok(sectoresService.Enumerar(filtro));
}