How to handle exception in .net

Question

i am trying to handle exception and save that exception in database

Function1()  
{  
    try  
    {  
        for(int i=0;i<dt.rows.count;i++)  
        {  
            Function2();  
        }  
    }  
    catch(exception ex)  
    {  
        saveInDB(ex.message.tostring(),id);  
    }  

}  

Function2()  
{  
    try  
    {  
        function3()  
    }  
    catch(exception ex)  
    {  
        throw ex;  
    }  
}  

Function3()  
{  
    try  
    {  
        function4()  
    }  
    catch(exception ex)  
    {  
        throw ex;  
    }  
}  

Function4()  
{  
    try  
    {  
        code;  
    }  
    catch(exception ex)  
    {  
        throw ex;  
    }  
}

suppose i got a exception in method4 then it will throw it to function3->Function2->function1 and then function1 will write exception in database.

but after writing exception in DB i want to continue for loop.

so how should i do?

Why do you have a function that only starts an other function? — Vloxxity
– Vloxxity, Commented Feb 19, 2013 at 9:47

Henk Holterman · Accepted Answer · 2013-02-19 09:55:01Z

1

but after writing exception in DB i want to continue for loop

That is only possible by putting an (extra) try/catch inside the for loop. You should do so only if the next round of the loop is independent and you are certain there is no harm done to your system.

Ask yourself: After an unknown error, do I still dare to write business-data to the database?

Notice that your code is in violation of some best-practices:

throw ex; resets the stack-trace. Replace it with throw;
when the catch blocks in function2 - function4 don't do anything with the exceptions, remove the try/catch altogether.

edited Feb 19, 2013 at 9:55

answered Feb 19, 2013 at 9:48

Henk Holterman

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Comments

Matthias Meid · Accepted Answer · 2013-02-19 09:55:45Z

1

You can put your try-catch into the for loop's body:

Function1()  
{  
    for(int i=0;i<dt.rows.count;i++)  
    {  
        try  
        {  
            Function2();  
        }  
        catch(Exception ex)  
        {  
            saveInDB(ex.message.tostring(),id);  
        }  
    }
}

Keep in mind, however, that IO such as saving to DB may be pretty unreliable (and slow). This in turn might lead to further exception being thrown in your catch, which will tear down your loop.

Therefore it might be better to store all thrown exception in a data structure and dump them to the DB at once. This way the loop runs for each and every row.

Function1()  
{
    var errors = new LinkedList<Exception>();
    for(int i=0;i<dt.rows.count;i++)  
    {  
        try  
        {  
            Function2();  
        }  
        catch(Exception ex)  
        {  
            errors.AddLast(ex);
        }  
    }
    if(errors.Count > 0)
    {        
        // now you got all exception in errors and can dump
        // them in one block
    }
}

edited Feb 19, 2013 at 9:55

answered Feb 19, 2013 at 9:49

Matthias Meid

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2 Comments

Matthias Meid Over a year ago

@TruptiGhorpade Nice to read; could you accept an answer or post the solution to your problem?

Blake Niemyjski Over a year ago

I'm not sure I'd I would do the second part and add them to a list. But it would be best to just catch it if you can handle it. Also for logging I'd recommend this oss project that I work on: github.com/exceptionless/Exceptionless It's tested and free.

Jean · Accepted Answer · 2013-02-19 09:49:17Z

0

As long as any try-catch block throws the exception, the program cannot continue. If you want your program to be continue after exception handling, my suggestion would be not to use:

throw ex;

answered Feb 19, 2013 at 9:49

Jean

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Comments

Indi · Accepted Answer · 2013-02-19 09:51:06Z

0

If you need to continue looping after an exception within the loop, you need to add a try/catch block within the loop as below;

try{

    for(int i=0; i<10; i++){
       try{
         //do your work here
       }
       catch (Exception e){
         //write to db here and then it will continue in the for loop
       }
    }

    //rest of the code
}
catch (Exception ex){
  //write to db
}

answered Feb 19, 2013 at 9:51

Indi

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