Filter out null values when grouping by annotation (#3521)

* Add a regression test

Signed-off-by: Noah Held <noahheld17@gmail.com>

* Fix the bug

Signed-off-by: Noah Held <noahheld17@gmail.com>

* Formatting

Signed-off-by: Noah Held <noahheld17@gmail.com>

---------

Signed-off-by: Noah Held <noahheld17@gmail.com>

internal/lookoutv2/repository/groupjobs_test.go

@@ -961,6 +961,13 @@ func TestGroupByAnnotation(t *testing.T) {
  "test-annotation-1": "test-value-3",
  },
  }, converter, store)
+ manyJobs(3, &createJobsOpts{
+ queue: queue,
+ jobSet: jobSet,
+ annotations: map[string]string{
+ // Note the absence of the key "test-annotation-1".
+ },
+ }, converter, store)
 
  result, err := repo.GroupBy(
  armadacontext.TODO(),

internal/lookoutv2/repository/querybuilder.go

@@ -406,6 +406,17 @@ func (qb *QueryBuilder) GroupByJsonb(
  return nil, err
  }
 
+ if groupedField.IsAnnotation {
+ // scanGroup expects values in the grouped-by field not to be null. In
+ // the case where we are grouping by an annotation key, we end up with
+ // a `GROUP BY` clause like:
+ //
+ // GROUP BY annotations->>'host_instance_id'
+ //
+ // This evaluates to null if the annotations object does not contain
+ // the key in question, so we need to filter out such rows.
+ filters = append(filters, &model.Filter{Field: groupedField.Field, Match: model.MatchExists, IsAnnotation: true})
+ }
  where, err := qb.makeWhereJsonb(filters)
  if err != nil {
  return nil, err