fix: wrong odata count in filter with groupby (#352)

Encase the groupby within an additional SELECT statement to ensure
accurate row counting.

---------

Co-authored-by: I543501 <lars.lutz@sap.com>
Co-authored-by: Johannes Vogel <31311694+johannes-vogel@users.noreply.github.com>

db-service/lib/SQLService.js

@@ -230,16 +230,15 @@ class SQLService extends DatabaseService {
  if (max === undefined || (n < max && (n || !offset))) return n + offset
  }
  // REVISIT: made uppercase count because of HANA reserved word quoting
- const cq = cds.ql.clone(query, {
- columns: [{ func: 'count', as: 'COUNT' }],
+ const cq = SELECT.one([{ func: 'count', as: 'COUNT' }]).from(
+ cds.ql.clone(query, {
  localized: false,
  expand: false,
- limit: 0,
- orderBy: 0,
- })
- const { sql, values } = this.cqn2sql(cq)
- const ps = await this.prepare(sql)
- const { count, COUNT } = await ps.get(values)
+ limit: undefined,
+ orderBy: undefined,
+ }),
+ )
+ const { count, COUNT } = await this.onSELECT({ query: cq })
  return count ?? COUNT
  }
 

test/scenarios/bookshop/read.test.js

@@ -30,6 +30,15 @@ describe('Bookshop - Read', () => {
  expect(res.data['@odata.count']).to.be.eq(5)
  })
 
+ test('Books $count with $top=1 and groupby', async () => {
+ const res = await GET(
+ `/browse/ListOfBooks?$apply=groupby((ID),aggregate(ID with countdistinct as countBookings))&$count=true&$top=1`,
+ )
+ expect(res.status).to.be.eq(200)
+ expect(res.data.value.length).to.be.eq(1)
+ expect(res.data['@odata.count']).to.be.eq(5)
+ })
+
  test('Path expression', async () => {
  const q = CQL`SELECT title, author.name as author FROM sap.capire.bookshop.Books where author.name LIKE '%a%'`
  const res = await cds.run(q)

test/scenarios/sflight/read.test.js

@@ -44,6 +44,7 @@ describe('SFlight - Read', () => {
  // REVISIT: works in sflight not in tests
  // 'Bookings?$apply=concat(groupby((BookingID,ConnectionID,CurrencyCode_code,FlightDate,ID,TravelID,airline,status))/aggregate($count%20as%20UI5__leaves),aggregate(FlightPrice,CurrencyCode_code),groupby((airline,airlineName),aggregate(FlightPrice,CurrencyCode_code))/concat(aggregate($count%20as%20UI5__count),top(53)))',
  'Bookings?$apply=groupby((airline,airlineName),aggregate(FlightPrice with average as avgPrice,FlightPrice with max as maxPrice,FlightPrice with min as minPrice))&$skip=0&$top=1',
+ `Bookings?$apply=filter(airline eq 'EA' and status eq 'B')/groupby((ID),aggregate(FlightPrice,CurrencyCode_code))&$count=true&$skip=0&$top=1`
  ]
 
  test.each(analyticsPaths)('/analytics/%s', async p => {