How does sorting work with limit in kotlin exposed model?

Question

I have following snippet of code:

UserDataModel
                .find {
                    UserDataTable.type eq type and (
                            UserDataTable.userId eq userId
                            )
                }
                .limit(count)
                .sortedByDescending { it.timestamp }

sortedByDescending is a part of kotlin collections API. The my main concern is: how does exposed lib return top (according to timestamp) count rows from table if select query looks like this and does not contain ORDER BY clause?

SELECT USERDATA.ID, USERDATA.USER_ID, USERDATA.TYPE,
USERDATA.PAYLOAD, USERDATA."TIMESTAMP"
FROM USERDATA 
WHERE USERDATA.TYPE = 'testType'
and USERDATA.USER_ID = 'mockUser'
LIMIT 4

And is it possible that sometimes or somehow returned result would be different for the same data?

Really struggled here. Thank you in advance.

noiaverbale · Accepted Answer · 2019-03-19T14:32:10.043

6

You're sorting the results after query has been executed.

You need to use orderBy method as described in docs

UserDataModel
  .find {
    UserDataTable.type eq type and (UserDataTable.userId eq userId)
  }
  .limit(count)
  .orderBy(UserDataTable.timestamp to SortOrder.DESC)

edited Mar 19 '19 at 14:32

answered Mar 19 '19 at 08:05

noiaverbale

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3

`.orderBy(UserDataTable.timestamp to false)` is deprecated in favor to `.orderBy(UserDataTable.timestamp to SortOrder.DESC)`. I will update the wiki page. – Tapac Mar 19 '19 at 14:10
My problem was in outdated version of exposed (0.11). It does not contain orderBy method. May be this info will help someone – Илья Белейчев Mar 20 '19 at 06:17

How does sorting work with limit in kotlin exposed model?

1 Answers1