我如何在C＃中将变量从方法发送到该调用者方法的catch块？

Question

Let's say I have a method like this.

Boolean hasErrors = false;
try
{
    var anotherId = DoSomethingWithList(list);
}
catch (Exception ex)
{
    errorMessageDetail.Text = ex.Message;
    hasErrors = true;
}

And In my DoSomethingWithList method I am doing fancy stuff in an iteration.

public Guid? DoSomethingWithList(List<ofthings> myList)
{
    foreach (var member in myList)
    {
          //Do fancy and dangerous stuff in here.
    }
}

What I try to achieve is that, When I get an exception in DoSomethingWithList method I also want to know in which member of the list this exception has been thrown, and include it in errorMessageDetail . Thank you in advance.

Edit: I can not simply move my exception block into the loop itself because errorMessageDetail is connected with the aspx in the front end, and my DoSomethingWithList method is in my Business Layer.

Answer 1

You could create your specific exception type. Eg

public Guid? DoSomethingWithList(List<ofthings> myList)
{
    foreach (var member in myList)
    {
        try
        {
          //Do fancy and dangerous stuff in here.
        }
        catch (Exception ex)
        {
             throw new ListProcessingException(member, ex);
        }
    }
}

Answer 2

Try this.

public Guid? DoSomethingWithList(List<ofthings> myList){
foreach (var member in myList){
    try{
      //Do fancy and dangerous stuff in here.
    }
    catch(Exception e){
        throw new Exception(string.Format("{0} thrown by {1}", e.Message, member.ToString()), e);    
    }
}

I'm assuming member has a suitable implementation of ToString(), otherwise just use whatever property is relevant.

Answer 3

the only way to return state from DoSomethingWithList in case of error is to wrap its functionality in another try catch as @Stefan Steinegger said.

because if you dont catch the exception the (thread / callstack) will be killed and thus stack frames will be dead. (stack frame is where locals are stored)