Bug 24528: Add a syntax to x-koha-embed to specify counts

This patch adds a + syntax to specify on the x-koha-embed header that we
want the count of a relation in the response. For example:

GET /patrons/1
x-koha-embed: checkouts+count

Would return a JSON representation of a Koha::Patron, with a new
attribute added: checkouts_count, which will be the result of calling
$patron->checkouts->count.

This is all done automatically in to_api. This patch makes parsing the
x-koha-embed header build the right structure for passing to the to_api
method.

To test:
1. Apply this patch
2. Run:
   $ kshell
  k$ prove t/Koha/REST/Plugin/Query.t
=> SUCCESS: Tests pass!
3. Sign off :-D

Sponsored-by: ByWater Solutions
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Koha/REST/Plugin/Query.pm

@@ -263,7 +263,13 @@ sub _parse_embed {
         $result->{$curr} = { children => _parse_embed( $next ) };
     }
     else {
-        $result->{$curr} = {};
+        if ( $curr =~ m/^(?<relation>.*)\+count/ ) {
+            my $key = $+{relation} . "_count";
+            $result->{$key} = { is_count => 1 };
+        }
+        else {
+            $result->{$curr} = {};
+        }
     }
 
     return $result;

t/Koha/REST/Plugin/Query.t

@@ -140,7 +140,8 @@ get '/stash_embed' => sub {
                     'x-koha-embed' => [
                         'checkouts',
                         'checkouts.item',
-                        'library'
+                        'library',
+                        'holds+count'
                     ]
                 }
             }
@@ -304,7 +305,7 @@ subtest '_build_query_params_from_api' => sub {
 
 subtest 'stash_embed() tests' => sub {
 
-    plan tests => 12;
+    plan tests => 15;
 
     my $t = Test::Mojo->new;
 
@@ -316,6 +317,10 @@ subtest 'stash_embed() tests' => sub {
       ->status_is(200)
       ->json_is( { checkouts => { children => { item => {} } }, library => {} } );
 
+    $t->get_ok( '/stash_embed' => { 'x-koha-embed' => 'holds+count' } )
+      ->status_is(200)
+      ->json_is( { holds_count => { is_count => 1 } } );
+
     $t->get_ok( '/stash_embed' => { 'x-koha-embed' => 'checkouts,checkouts.item,patron' } )
       ->status_is(400)
       ->json_is(