CODEWITHSUNDEEP
c#sql-serverlinqlambda
ggon
ggon

Reputation: 53

Custom Sort in C# LINQ with LAMBDA

Even thought there's another topic with similar title, i search for a more generic answer.

I have a SQLSERVER Query to select userId's with a custom Order By clause. Something like this:

SELECT userID
FROM users
WHERE userName like '%whatever%'
ORDER BY 
 CASE
  WHEN UserID = 123 THEN 0
  WHEN UserID = 456 THEN 1
  WHEN UserID = 789 THEN 2
  ELSE 3
 END ASC,
 UserID

So, how do i replicate the same Order By structure, but using LINQ with LAMBDA in C#?

Here is my code so far:

var userID = db.User.Where(x => x.userName.Contains("whatever").OrderBy(x => x.userID).Select(x => x.userID).ToList();

Upvotes: 1

Views: 424

Answers (1)

Igor
Igor

Reputation: 62238

ORDER BY 
 CASE
  WHEN UserID = 123 THEN 0
  WHEN UserID = 456 THEN 1
  WHEN UserID = 789 THEN 2
  ELSE 3
 END ASC,
 UserID

is functionally equivalent to this Lambda

.OrderBy(_ => _.userID == 123 ? 0 : _.userID == 456 ? 1 : _.userID == 789 ? 2 : 3)
.ThenBy(_ => _.userID)

Upvotes: 2

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