I've got this...
public void FooAsync()
{
AsyncManager.OutstandingOperations.Increment();
Task.Factory.StartNew(() =>
{
try
{
doSomething.Start();
}
catch (Exception e)
{
AsyncManager.Parameters["exc"] = e;
}
finally
{
AsyncManager.OutstandingOperations.Decrement();
}
});
}
public ActionResult FooCompleted(Exception exc)
{
if (exc != null)
{
throw exc;
}
return View();
}
Is there a better way of passing an exception back to ASP.net?
Cheers, Ian.
Task will catch the exceptions for you. If you call task.Wait(), it will wrap any caught exceptions in an AggregateException and throw it.
[HandleError]
public void FooAsync()
{
AsyncManager.OutstandingOperations.Increment();
AsyncManager.Parameters["task"] = Task.Factory.StartNew(() =>
{
try
{
DoSomething();
}
// no "catch" block. "Task" takes care of this for us.
finally
{
AsyncManager.OutstandingOperations.Decrement();
}
});
}
public ActionResult FooCompleted(Task task)
{
// Exception will be re-thrown here...
task.Wait();
return View();
}
Simply adding a [HandleError] attribute isn't good enough. Since the exception occurs in a different thread, we have to get the exception back to the ASP.NET thread in order to do anything with it. Only after we have the exception thrown from the right place will the [HandleError] attribute be able to do its job.
Try putting an attribute like this in FooAsync action:
[HandleError (ExceptionType = typeof (MyExceptionType) View = "Exceptions/MyViewException")]
This way you can create a view to display the detailed error to the user.
Related
I'd like to allow all handler methods in a Razor Page to be wrapped by some sort of logic to handle specific exceptions that are more or less validation exceptions.
I've tried the following, but still get the developer exception page:
public override async Task OnPageHandlerExecutionAsync(PageHandlerExecutingContext context, PageHandlerExecutionDelegate next)
{
try
{
await next();
}
catch(NotImplementedException ex)
{
_logger.LogWarning(ex, ex.Message);
ModelState.AddModelError(string.Empty, "Oops... this isn't all done yet.");
context.Result = Page();
}
catch (DomainValidationException ex)
{
ModelState.Include(ex.Results);
context.Result = Page();
}
}
The exception does not appear to bubble up from the await next() call and is handled in aspnetcore somehow.
It turns out that the next returns a result that needs to be inspected to get the exception and return the result.
The final implementation looks something like this:
public override async Task OnPageHandlerExecutionAsync(PageHandlerExecutingContext context, PageHandlerExecutionDelegate next)
{
var result = await next();
if (result.Exception != null)
{
if (result.Exception is NotImplementedException nex)
{
result.ExceptionHandled = true;
_logger.LogWarning(nex, nex.Message);
ModelState.AddModelError(string.Empty, "Oops... this isn't all done yet.");
}
else if (result.Exception is DomainValidationException dex)
{
result.ExceptionHandled = true;
ModelState.Include(dex.Results);
}
if (result.ExceptionHandled)
{
result.Result = Page();
}
}
}
I have a log() method to avoid try catch statement in forEach() below which was working in other code.
public <T> Consumer<T> log(LogConsumer<T, Throwable> logConsumer)
{
return i -> {
try
{
logConsumer.accept(i);
}
catch (Throwable e)
{
log("e = " + e);
}
};
}
#FunctionalInterface
public interface LogConsumer<T, E extends Throwable> {
void accept(T t) throws E;
}
Now I just want to use log in forEach below but I have the red rippled line in LINE such that
new Task.runJob(job, type))
I have red rippled line under job, type in
"runJob(Job, JobType) in Task cannot be applied to (java.lang.Object, < lambda parameter>)"
Now sure how to fix it to use log in forEach just to avoid
try-catch inside of it.
execute() {
Map<Job, JobType> map = getJobMap();
map.forEach( log((job, type)-> new Taks().runJob(job,type)) ); // LINE: error here
}
class Task {
public String runJob(Job job, JobType type) throws Exception
{
...
return result;
}
}
It happens because you cannot execute functions that throw exceptions using lambda expressions. You have to handle the exception using try-catch block. However, in order for your code to look more readable, create a function, that will handle the exception and return the desired result.
class Task {
public String runJob(Job job, JobType type)
{
try {
...
return result;
} catch (Exception e) {
log.error(e.getMessage());
}
return null;
}
}
In case if you care what will be the result, map it and filter for the result of your function is not null, otherwise, ignore it, but watch logs for any errors.
And then call it like shown below.
Notice: both ways work below, but the second way is more robust because you can handle the scenario when not all jobs were executed without exception.
execute() {
Map<Job, JobType> map = getJobMap();
// First way
map.forEach( log((job, type) -> new Taks().runJob(job,type)) );
// Another way
List<Object> batchResult = map.entrySet().stream()
.map((job, type) -> new Task().runJob(jon, type))
.filter(Objects::nonNull)
.collect(Collectors.toList());
if (batchResult.size() == map.size()) {
// everythings is ok (all operations resulted in non-null result
} else {
// Have to study logs and figure out what went wrong
}
}
I have a WebAPI2 mvc app where I'm doing Get/Post to another api. My code looks like below
public Task<SomeEntity> AddAsync(SomeEntity someEntity)
{
try
{
var response = apiService.PostItem(url, someEntity);
if (response == null || response!="Successful")
{
throw new InvalidOperationException(response);
}
}
catch (Exception ex)
{
_logger.Error("Error " + ex.Message);
// how to return this error or exception;
}
return Task.FromResult(someEntity);
}
If the call to the internal api return an exception string then I need to forward it from this method call. Any ideas how can I do it? thanks
You can use IHttpActionResult or HttpResponseMessage as your return type and return proper HTTP-Status codes. In case of exception you can return [if you return IHttpActionResult ]
public IHttpActionResult Error()
{
var error = new HttpError();
return ResponseMessage(Request.CreateErrorResponse(HttpStatusCode.BadRequest, error));
}
or as in your example, throw HttpResponseException with appropriate status code.
public Product GetProduct(int id)
{
Product item = repository.Get(id);
if (item == null)
{
var message = string.Format("Product with id = {0} not found", id);
throw new HttpResponseException(
Request.CreateErrorResponse(HttpStatusCode.NotFound, message));
}
else
{
return item;
}
}
This is continuation to my question: [How to get name data of multiple json object list that will be posted to web api?
I was able to update my code but now I am getting an erexception on
if (db.Sales1.Any(sl => sl.ExtSerial != s.ExtSerial))
Exception goes: An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll but was not handled in user code
Additional information: The context cannot be used while the model is being created. This exception may be thrown if the context is used inside the OnModelCreating method or if the same context instance is accessed by multiple threads concurrently. Note that instance members of DbContext and related classes are not guaranteed to be thread safe.
Here is the code:
public HttpResponseMessage PostSales(List<Sales> Sales, [FromUri] string auth)
{
try
{
if (ModelState.IsValid)
{
if (auth == "KDI")
{
#region Stable but not multiline
//Int64 rs = db.Sales1.Where(sl => sl.Serial == Sales.Serial).Count();
//if (1 == rs)
//{
// return Request.CreateErrorResponse(HttpStatusCode.Conflict, " Duplicate Found!");
//}
//else
//{
// db.Sales1.Add(Sales);
// db.SaveChanges();
// return Request.CreateErrorResponse(HttpStatusCode.OK, "Added!");
//}
#endregion
Parallel.ForEach(Sales, s =>
{
if (db.Sales1.Any(sl => sl.ExtSerial != s.ExtSerial))
{
db.Sales1.Add(s);
db.SaveChanges();
}
else
{
return;
}
});
return Request.CreateErrorResponse(HttpStatusCode.OK, "Success!");
}
else
{
return Request.CreateResponse(HttpStatusCode.Unauthorized, "Unauthorized Access!");
}
}
else
{
return Request.CreateResponse(HttpStatusCode.InternalServerError, "Something's wrong with the JSON model you sent me.");
}
}
catch (Exception ex)
{
return Request.CreateResponse(HttpStatusCode.InternalServerError, ex.Message);
}
}
I am using Janus(Third Party) Grid and getting the "System.StackOverflowException". Don't know how to solve it. I would like to appreciate for any help.
private void gridEX1_FormattingRow(object sender, RowLoadEventArgs e)
{
int index = e.Row.RowIndex;
try
{
if (!Convert.IsDBNull(gridEX1.GetRow(index).Cells["HEADER_ORDER_PACKAGE_ROW_ID"].Value))
{
if (Convert.ToInt32(gridEX1.GetRow(index).Cells["HEADER_ORDER_PACKAGE_ROW_ID"].Value) == PARENT_ORDER_PACKAGE_ID)
{
**gridEX1.MoveToRowIndex(index);**
GridEXRow curRow = gridEX1.GetRow();
if (curRow != null)
{
curRow.Expanded = true;
}
}
}
}
catch (Exception ex)
{
}
}
It seems that one of the lines inside your handler invoke the handler itself again. And so on, so you get StackOverflow.