LINQ enumeration list doesn't show up the error when accessed it for second time while debugging

Question

I'm making a database call with linq and it is returning some results to me. Following is the code for the same:

var resultSet = DataContext.GetList(id);

foreach(var result in resultSet)
{
    // do something here with result
}

After this, I try to access again same resultSet as below:

foreach(var result in resultSet)
{
    // do something here with result
}

When I'm in debug mode it doesn't throw any error, instead it simply exits debug mode and execution is completed and focus comes back to page.

I want to know why it is not throwing any error in debug mode that I'm using the enumeration for the second time? Am I missing anything? All other errors are throwing exceptions even in the debug mode.

Update: I intentionally didn't do that second calling. It was done by mistake, but it took sometime for me to find that error, if it would have thrown an error, then I would have easily fixed it. This is reason I posted this question here.

Note: I'm doing this throw a ajax call.

Answer 1

To make an informed decision we would really need to know what happens in between, however, it is possible that your context is perhaps being disposed before you call the query a second time?

If you plan to iterate over the result set more than once you may aswell cache the list on the first call to avoid making another unneccessary database call. LINQ only retrieves the data from the database once it is accessed i.e. each time you enumerate your result set.

Try doing this and see if it helps:

var resultSet = DataContext.GetList(id).ToList();

foreach(var result in resultSet)  
{  
    // do something here with result  
} 
...

foreach(var result in resultSet)  
{  
    // do something here with result  
} 

Answer 2

I think if you go to Debug (Menu)> Exceptions and check the checkbox under Thrown for Common Language Runtime Errors. Now Visual Studio debugger should break when the error occurs and you should be able to see what's happening.