Currently, +count embeds (e.g. claims+count) are computed in Perl via
$object->$relation->count during to_api serialization. This means they
cannot be used in _order_by and each count triggers a separate SQL query
per row (N+1).
This patch makes dbic_merge_prefetch detect +count embeds and, when a
matching DBIC relationship exists, inject a correlated COUNT subquery
via +select/+as instead of adding a prefetch.
The order_by entries referencing count aliases are fixed up to strip the
me. prefix, since +as aliases are virtual columns not bound to a table.
In to_api, the is_count handler now checks for the pre-computed column
via get_column before falling back to the Perl-level ->count call. This
preserves backward compatibility for Koha-level methods that don't have
a corresponding DBIC relationship.
Test plan:
1. Apply patches
2. Run:
$ ktd --shell
k$ prove t/Koha/REST/Plugin/Query.t \
t/db_dependent/Koha/Object.t \
t/db_dependent/Koha/REST/Plugin/Objects.t
=> SUCCESS: Tests pass!
3. Sign off :-D
Signed-off-by: Tomás Cohen Arazi <tomascohen@theke.io>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Pedro Amorim <pedro.amorim@openfifth.co.uk>
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