How to return JSON result from a custom exception filter?
I would like to create a custom exception filter that will catch exceptions thrown in controller actions that return JSON results.
I would like to refactor the following action method:
public JsonResult ShowContent()
{
try
{
// Do some business logic work that might throw a business logic exception ...
//throw new ApplicationException("this is a business exception");
var viewModel = new DialogModel
{
FirstName = "John",
LastName = "Doe"
};
// Other exceptions that might happen:
开发者_如何学Go//throw new SqlException(...);
//throw new OtherException(...);
//throw new ArgumentException("this is an unhandeled exception");
return
Json(
new
{
Status = DialogResultStatusEnum.Success.ToString(),
Page = this.RenderPartialViewToString("ShowContent", viewModel)
});
}
catch (ApplicationException exception)
{
return Json(new { Status = DialogResultStatusEnum.Error.ToString(), Page = exception.Message });
}
catch (Exception exception)
{
return Json(new { Status = DialogResultStatusEnum.Exception.ToString(), Page = "<h2>PROBLEM!</h2>" });
}
}
}
What I would like to do is create a custom exception filter attribute that will catch any exceptions thrown in the action follow the following logic:
- Check if there was an exception
- No: return
- yes:
- If BusinessLogic exception – return a JSON result
- If other unhandled exception:
- Log
- Return another JSON result with a different result code
I found it possible to solve this problem using the code found in this article (with minor changes to it.)
public class HandleJsonExceptionAttribute : ActionFilterAttribute
{
#region Instance Methods
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
if (filterContext.Exception != null)
{
filterContext.HttpContext.Response.StatusCode = (int)System.Net.HttpStatusCode.InternalServerError;
filterContext.Result = new JsonResult()
{
JsonRequestBehavior = JsonRequestBehavior.AllowGet,
Data = new
{
Error = filterContext.Exception.Message
}
};
filterContext.ExceptionHandled = true;
}
}
#endregion
}
public class YourController : BaseController
{
public JsonResult showcontent()
{
// your logic here to return foo json
return Json ( new { "dfd" }); // just a dummy return text replace it wil your code
}
}
public class BaseController : Controller
{
// Catch block for all exceptions in your controller
protected override void OnException(ExceptionContext filterContext)
{
base.OnException(filterContext);
if (filterContext.Exception.Equals(typeof(ApplicationException)))
{
//do json and return
}
else
{
// non applictaion exception
// redirect to generic error controllor and error action which will return json result
}
}
}
Refer this link to see how to create and use HandleError attribute
*EDIT for HandleAttribute for Actions*
//not tested code
public class HandleErrorfilter : HandleErrorAttribute
{
public string ErrorMessage { get; set; }
public override void OnException(ExceptionContext filterContext)
{
string message = string.Empty;
//if application exception
// do something
else
message = "An error occured while attemting to perform the last action. Sorry for the inconvenience.";
}
else
{
base.OnException(filterContext);
}
}
public class YourController : BaseController
{
[HandleErrorfilter]
public JsonResult showcontent()
{
// your logic here to return foo json
return Json ( new { "dfd" }); // just a dummy return text replace it wil your code
}
}
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