PieterBrinkman.com

A lot of times I need to check a statement within my LINQ-query and I wish there was a possibility of a IF statement within LINQ.

The following code is the solution to my IF problem. I use a temporary variable (let isOlderThen30) to check if a statement is true. Then in my WHERE statement I use the temporary variable in a INFLINE IF.

For this example I use my Blogger class with some data

public class Blogger
{
 public string FirstName { get; set; }
 public string LastName { get; set; }
 public int Age { get; set; }
 public string Blog { get; set; }
}

List personList = new List{
 new Blogger { FirstName = "Pieter", LastName = "Brinkman", Age = 27, Blog = "http://blog.newguid.net" },
 new Blogger { FirstName = "Mark", LastName = "van Aalst", Age = 26, Blog = "http://www.markvanaalst.com" },
 new Blogger { FirstName = "Bas", LastName = "Hammendorp", Age = 32, Blog = "http://www.hammendorp.net" }
};

It’s kind of hard to think of a easy good example, but here it is. In this example I want to set the Age property to “Older then 30” when the Blogger is older then 30 (how useful!).

//If a blogger is older then set Age text to "Older then 30"

var rawList = from item in personList
  let <strong>isOlderThen30</strong> = item.Age &gt; 30
  select new
  {
   Name = item.FirstName,
   Age = (isOlderThen30 ? "Older then 30" : item.Age.ToString()),
  };

//GENERATE OUTPUT

foreach (var item in rawList)
{
 Response.Write(item.Name + " (" + item.Age + ")<br />");
}

//OUTPUT
//Pieter (27)
//Mark (26)
//Bas (Older then 30)

Hope that the example is clear. If you have any questions let me know.

// UPDATE (3 aug 2009) //

I thought about the codeexample and offcourse you can do it shorter (but less readable with complex queries).

var rawList = from item in personList
  select new
  {
   Name = item.FirstName,
   Age = (item.Age > 30 ? "Older then 30" : item.Age.ToString()),
  };