How can I count a query from squeryl

Question

I have a method which return a Query:

def list:Query[User] = from(users)(u => where(u.age>20) select(u))

Now I want to count the list, but this method:

list.count(_ => true)

will get and loop all elements in the list.

I want to find a solution to make a "select count" statement from the Query[User], but not found yet.

Or I have to write another method for count:

def countList: Long = from(users)(u => where(u.age>20) compute(count))

Which is not what I want.

score 2 · Accepted Answer · edited Jun 18 '13 at 14:17

2

Try to compose the two queries:

from(list)(_ => compute(count))

edited Jun 18 '13 at 14:17

Freewind

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answered Jun 18 '13 at 08:32

stefan.schwetschke

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It can't be compiled: `missing arguments for method from in trait FromSignatures; follow this method with _ if you want to treat it as a partially applied function` – Freewind Jun 18 '13 at 10:16
1

You would query the `Queryable` the same as a `Table`, so the syntax above looks more illustrative. The compilable code would probably look like: `from(list)(l => compute(count))` – jcern Jun 18 '13 at 11:58

score 0 · Answer 2 · answered Apr 02 '15 at 14:33

In such cases it might make sense to make a common query builder, so you can keep the condition logic at a single place. It's handy when you are paging a query result set.

def queryBuilder[T](action: User => WhereState[Conditioned] => QueryYield[T]) : Query[T] = from(users)(u => action(u)(where(u.age>20)))

def countQuery = queryBuilder(u => w => w.compute(count))

def selectQuery = queryBuilder(u => w => w.select(u))

score 0 · Answer 3 · answered May 26 '15 at 19:18

Here is an example of DAO object:

def countByJobPostingId(jobPostingId: Int): Long = {
  inTransaction {
    val q = from(table)(t =>
      where(t.jobPostingId === jobPostingId)
        compute count
    )

    LOG.debug(q.statement)

    q.head.measures
  }
}

How can I count a query from squeryl

3 Answers3