Ordering data by boolean

Question

I have a bit of EF Lambda code which returns a list of data from the db table, then orders by a field called IsDefault

At first, the code was

var listOfData = Db
    .TableName
    .Where(u => u.UserId == userId)
    .OrderBy(u => u.IsDefault)
    .ToList();

Which when writing down, sounds correct. However is wrong as this will order by 0 > 1, and True = 1.

So I changed the statement to;

var listOfData = Db
    .TableName
    .Where(u => u.UserId == userId)
    .OrderBy(u => u.IsDefault ? 0 : 1)
    .ToList();

However, I could have also written this 2 other ways.

.OrderBy(u => !u.IsDefault)

OR

.OrderByDescending(u => u.IsDefault)

Now in my mind, u.IsDefault ? 0 : 1 reads better, and the other two could be misread as the not wanting the default value first.

What is your view on this?

Answer 1

I wouldn't use either ordering on the server side because it looks like the ordering only matters for displaying the data. I cannot imagine why it should matter from the programmatic point of view.

Let the client, its view, its display control, or whatever sort the items according to its needs.

Answer 2

When reading the code the following is most clear and fastest to understand:

OrderBy(u => u.IsDefault ? 0 : 1)

It sounds like: "order by: if default then 0=top if not default then 1=bottom"

The following is hard to understand:

OrderByDescending(u => u.IsDefault)

It sounds like: "Oder descending by IsDefault? WTH? Which goes first default or not default? true or false? OK true=1 and false=0 so false is first so not default is first, but it is descending then non default is last so default is first. Finally I get it: Default value goes first."

Answer 3

I would go with .OrderBy(u => !u.IsDefault) the other 2 don't quite fit in my opinion.

You have 2 alternative options

1. Declare a property that is called IsNotDefault and use it there .OrderBy(u => u.IsNotDefault) it will return !IsDefault so it flips the results.

2. The best option would be to use enum :

   public enum MyEnum
   {
       Default,
       NonDefault,
   }
   

   Note think of a better name for that enum..

   Now you can use it just like your ternary operator but without the ternary operator :

   public MyEnum IsDefault {...}
   .OrderBy(u => u.IsDefault)
   

   You can even apply more values and it will still order them in the right way.