Exception handling and redirecting from view component

Question

How can I implement exception handling in my view component?

Wrapping the logic from my action method into try/catch blocks doesn't catch any exceptions thrown within a view component itself, and I don't want the app to stop functioning regardless of any errors. This is what I'm doing so far and trying to accomplish:

Action Method

public IActionResult LoadComments(int id)
{
  try
  {
    return ViewComponent("CardComments", new { id });
  }
  catch (SqlException e)
  {
    return RedirectToAction("Error", "Home");
  }
}

To reiterate, this does not catch a SqlException that occurs inside the view component itself, and thus it fails to redirect.

View Component

public class CardCommentsViewComponent : ViewComponent
{
  public async Task<IViewComponentResult> InvokeAsync(int id)
  {
    try
    {
      IEnumerable<CardCommentData> comments = await DbHelper.GetCardCommentData(id);
      return View(comments);
    }
    catch (SqlException e)
    {
      //Redirect from here if possible?
    }
  }
}

Can I accomplish this from the controller's action method? If not, how can I redirect from the view component itself? I've tried researching this problem and came up empty. Any information would be helpful.

Answer 1

You can try to redirect to another page using HttpContextAccessor.HttpContext.Response.Redirect:

public class CardCommentsViewComponent : ViewComponent
{

    private readonly IHttpContextAccessor _httpContextAccessor;
    public CardCommentsViewComponent( IHttpContextAccessor httpContextAccessor)
    {

        _httpContextAccessor = httpContextAccessor;
    }
    public async Task<IViewComponentResult> InvokeAsync(int id)
    {
        try
        {
            IEnumerable<CardCommentData> comments = await DbHelper.GetCardCommentData(id);
            return View(comments);
        }
        catch (SqlException e)
        {
            _httpContextAccessor.HttpContext.Response.Redirect("/About");

            return View(new List<CardCommentData>());
        }
    }
}

Register in DI :

services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();

But the preferred way is using global exception handler /filter to trace the exception and redirect to related error page :

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/error-handling?view=aspnetcore-2.2