Bug 28774: Don't store blank values for rental discount

This patch adds 'can_be_blank => 0' for the rentaldiscount rule to prevent
storing blank values in the database

Additionally, if there is no charge we do not need to check for a discount
and can simply return

To test:
1 - Set rental discount to "" to a rule in circulation rules
2 - Checkout an item that will follow this rule
3 - Check the intranet log:
    [WARN] Argument "" isn't numeric in subtraction (-) at /kohadevbox/koha/C4/Circulation.pm line 3385.
4 - Apply patch and restart all
5 - Update database
6 - Set the rule to "" again
7 - Check the DB, no rule is stored
    SELECT * FROM circulation_rules WHERE rule_name = 'rentaldiscount';
8 - Checkout the item again
9 - No warns in log

Signed-off-by: David Nind <david@davidnind.com>

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

C4/Circulation.pm

@@ -3385,19 +3385,19 @@ sub GetIssuingCharges {
     if ( my $item_data = $sth->fetchrow_hashref ) {
         $item_type = $item_data->{itemtype};
         $charge    = $item_data->{rentalcharge};
-        # FIXME This should follow CircControl
-        my $branch = C4::Context::mybranch();
-        my $patron = Koha::Patrons->find( $borrowernumber );
-        my $discount = Koha::CirculationRules->get_effective_rule({
-            categorycode => $patron->categorycode,
-            branchcode   => $branch,
-            itemtype     => $item_type,
-            rule_name    => 'rentaldiscount'
-        });
-        if ($discount) {
-            $charge = ( $charge * ( 100 - $discount->rule_value ) ) / 100;
-        }
         if ($charge) {
+            # FIXME This should follow CircControl
+            my $branch = C4::Context::mybranch();
+            my $patron = Koha::Patrons->find( $borrowernumber );
+            my $discount = Koha::CirculationRules->get_effective_rule({
+                categorycode => $patron->categorycode,
+                branchcode   => $branch,
+                itemtype     => $item_type,
+                rule_name    => 'rentaldiscount'
+            });
+            if ($discount) {
+                $charge = ( $charge * ( 100 - $discount->rule_value ) ) / 100;
+            }
             $charge = sprintf '%.2f', $charge; # ensure no fractions of a penny returned
         }
     }

Koha/CirculationRules.pm

@@ -156,6 +156,7 @@ our $RULE_KINDS = {
     },
     rentaldiscount => {
         scope => [ 'branchcode', 'categorycode', 'itemtype' ],
+        can_be_blank => 0,
     },
     reservesallowed => {
         scope => [ 'branchcode', 'categorycode', 'itemtype' ],

installer/data/mysql/atomicupdate/bug_28774_remove_blank_rentaldiscount.perl

@@ -0,0 +1,8 @@
+$DBversion = 'XXX';
+if( CheckVersion( $DBversion ) ) {
+    $dbh->do(q{
+        DELETE FROM circulation_rules
+        WHERE rule_name = 'rentaldiscount' AND rule_value=''
+    });
+    NewVersion( $DBversion, 28774, "Delete blank rental discounts");
+}