Fix issue #7956: PHP 8 compatibility for custom field integer types

PHP 8 changed loose comparison behavior: '' != 0 is now true (was false in PHP 7).
This caused empty custom field values to be written as '' instead of NULL
for integer/list columns (types 8, 9, 12), triggering MySQL error:
'Incorrect integer value: '' for column'

Changes:
- Functions.php: Replace loose comparison with explicit empty/null/zero checks
  in sqlCustomField(); cast values to (int) for safer integer column inserts
- InputUtils.php: legacyFilterInput() now returns type-appropriate empty values
  (0 for int, 0.0 for float) instead of always returning ''

Affects: FamilyEditor, PersonEditor, GroupPropsEditor, CSVImport

Author: DawoudIO

src/ChurchCRM/utils/InputUtils.php

@@ -182,7 +182,16 @@ public static function legacyFilterInput($sInput, $type = 'string', $size = 1)
                     throw new \InvalidArgumentException('Invalid "type" for legacyFilterInput provided');
             }
         } else {
-            return '';
+            // PHP 8 compatibility: return type-appropriate empty values
+            // to avoid loose comparison issues (e.g., '' != 0 is true in PHP 8)
+            switch ($type) {
+                case 'int':
+                    return 0;
+                case 'float':
+                    return 0.0;
+                default:
+                    return '';
+            }
         }
     }
 }

src/Include/Functions.php

@@ -937,10 +937,12 @@ function sqlCustomField(string &$sSQL, $type, $data, string $col_Name, $special)
     // list selects
         case 9:
         case 12:
-            if ($data != 0) {
-                $sSQL .= $col_Name . " = '" . $data . "', ";
-            } else {
+            // PHP 8 changed loose comparison: '' != 0 is now true (was false in PHP 7)
+            // Explicitly check for empty string/null/zero to maintain original behavior
+            if ($data === '' || $data === null || (int) $data === 0) {
                 $sSQL .= $col_Name . ' = NULL, ';
+            } else {
+                $sSQL .= $col_Name . " = '" . (int) $data . "', ";
             }
             break;