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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?

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3 Answers 3

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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.

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  • \$\begingroup\$ Good point actually. Could just do the ordering when building up the view model. \$\endgroup\$ Jan 12, 2017 at 13:46
  • \$\begingroup\$ I am going with this answer, as it is the simpler solution for my needs. Thanks for your help. \$\endgroup\$ Jan 13, 2017 at 10:59
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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."

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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.

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  • \$\begingroup\$ Yeah actually considered using Enums, will take a look. \$\endgroup\$ Jan 12, 2017 at 13:46
  • \$\begingroup\$ Why the down-vote ? \$\endgroup\$
    – Denis
    Jan 12, 2017 at 15:28
  • \$\begingroup\$ Not me, you still got a +1 from me. \$\endgroup\$ Jan 12, 2017 at 15:31
  • \$\begingroup\$ I'm just wondering if there is anything incorrect in the answer :P \$\endgroup\$
    – Denis
    Jan 12, 2017 at 15:58
  • \$\begingroup\$ As much as this is a great option. For now my needs are purely for boolean, and it would require too much of a code update for introducing the Enum. Thanks for your help. \$\endgroup\$ Jan 13, 2017 at 10:59

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