c# linq where conditional if

Question

I have some linq code that I am trying to refactor because its not very good:

Basically, I am wondering if there is a better way to perform the following:

if (!string.IsNullOrWhiteSpace(_filter.AssignedTo)
{
var query = from ticket in dataClassesDataContext.TicketsIssues
            where ticket.ClosedDate == null 
            && cUser.GetUserNameUsingGUID(ticket.AssignTicketToUser) == _filter.AssignedTo                                                   
            select new
            {
                Priority = ticket.TicketPriority.TicketPriorityName,
                Description = ticket.Description.Replace("\n", ", "),
            };
}
else
{
var query = from ticket in dataClassesDataContext.TicketsIssues
            where ticket.ClosedDate == null 
            select new
            {
                Priority = ticket.TicketPriority.TicketPriorityName,
                Description = ticket.Description.Replace("\n", ", "),
            };
}

They are both identical apart from the where clause is checks for AssignTicketToUser.

I am hoping there is a nicer way to do this to avoid having to use an if else statement? I have a few of these code blocks and dont want to be duplicating code alot!

Mickael Caruso · Accepted Answer · 2012-12-14 02:07:27Z

8

var query = from ticket in dataClassesDataContext.TicketsIssues
            where ticket.ClosedDate == null 
            && (string.IsNullOrWhiteSpace(_filter.AssignedTo) ? true : cUser.GetUserNameUsingGUID(ticket.AssignTicketToUser) == _filter.AssignedTo)                                                   
            select new
            {
                Priority = ticket.TicketPriority.TicketPriorityName,
                Description = ticket.Description.Replace("\n", ", "),
            };

You can get rid of the if-else statement altogether. Transfer the if condition it to the 2nd where clause, and remove the !. That second where clause becomes a ternary operator.

If the condition is true, that is if _filter.AssignedTo is null, then don't test _filter.AssignedTo by returning true. If it's not null or empty, then proceed to the clause that was there in your original else block.

edited Dec 14, 2012 at 2:07

answered Dec 14, 2012 at 2:02

Mickael Caruso

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2 Comments

Risky Martin Over a year ago

Instead of condition1 ? true : condition2 you could write (condition1 || condition2).

Belliez Over a year ago

thanks, this is exactly what I am looking for.... and feel embarrassed I didnt think of this myself (combination of a new baby and late night working!). Thanks

mnsr · Accepted Answer · 2012-12-14 02:02:01Z

3

one way could be:

var query = from ticket in dataClassesDataContext.TicketsIssues
            where ticket.ClosedDate == null 
            select new
            {
                Priority = ticket.TicketPriority.TicketPriorityName,
                Description = ticket.Description.Replace("\n", ", "),
            };

if (!string.IsNullOrWhiteSpace(_filter.AssignedTo)
    query = query.Where(w => cUser.GetUserNameUsingGUID(w.AssignTicketToUser) == _filter.AssignedTo));

answered Dec 14, 2012 at 2:02

mnsr

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Comments

Preston Guillot · Accepted Answer · 2012-12-14 02:42:06Z

1

Take a look at the PredicateBuilder implementation from C# In a Nutshell, the And method should address your issue here, in a more generic way, and help build an understanding of LINQ and expression trees. You would end up with something like:

var query = from ticket in dataClassesDataContext.TicketsIssues
            where ticket.ClosedDate == null
            select new
            {
                Priority = ticket.TicketPriority.TicketPriorityName,
                Description = ticket.Description.Replace("\n", ", "),
            };

if (!string.IsNullOrWhiteSpace(_filter.AssignedTo))
{
     query = query.And(ticket => cUser.GetUserNameUsingGUID(ticket.AssignTicketToUser) == _filter.AssignedTo);
}

answered Dec 14, 2012 at 2:42

Preston Guillot

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