MDL-75358 reportbuilder: display nulls as empty cells for numeric/bool

course/classes/reportbuilder/local/formatters/completion.php

@@ -63,11 +63,11 @@ class completion {
     /**
      * Return number of days for methods daystakingcourse and daysuntilcompletion
      *
-     * @param int $value
+     * @param int|null $value
      * @param stdClass $row
      * @return int|null
      */
-    public static function get_days(int $value, stdClass $row): ?int {
+    public static function get_days(?int $value, stdClass $row): ?int {
         // Do not show anything if there is no userid.
         if (!$row->userid) {
             return null;

reportbuilder/classes/local/helpers/format.php

@@ -32,32 +32,38 @@ class format {
     /**
      * Returns formatted date.
      *
-     * @param int $value Unix timestamp
+     * @param int|null $value Unix timestamp
      * @param stdClass $row
      * @param string|null $format Format string for strftime
      * @return string
      */
-    public static function userdate(int $value, stdClass $row, ?string $format = null): string {
+    public static function userdate(?int $value, stdClass $row, ?string $format = null): string {
         return $value ? userdate($value, $format) : '';
     }
 
     /**
      * Returns yes/no string depending on the given value
      *
-     * @param bool $value
+     * @param bool|null $value
      * @return string
      */
-    public static function boolean_as_text(bool $value): string {
+    public static function boolean_as_text(?bool $value): string {
+        if ($value === null) {
+            return '';
+        }
         return $value ? get_string('yes') : get_string('no');
     }
 
     /**
      * Returns float value as a percentage
      *
-     * @param float $value
+     * @param float|null $value
      * @return string
      */
-    public static function percent(float $value): string {
+    public static function percent(?float $value): string {
+        if ($value === null) {
+            return '';
+        }
         return get_string('percents', 'moodle', format_float($value));
     }
 }

reportbuilder/classes/local/report/column.php

@@ -479,7 +479,8 @@ final class column {
      * fields, and $additionalarguments are those passed on from this method):
      *
      * The type of the $value parameter passed to the callback is determined by calling {@see set_type}, this type is preserved
-     * if the column is part of a report source and is being aggregated
+     * if the column is part of a report source and is being aggregated.
+     * For entities that can to be left joined to a report, the first argument to their column callbacks must be nullable.
      *
      * function($value, stdClass $row[, $additionalarguments]): string
      *
@@ -649,6 +650,9 @@ final class column {
      */
     public static function get_default_value(array $values, int $columntype) {
         $value = reset($values);
+        if ($value === null) {
+            return $value;
+        }
 
         // Ensure default value is cast to it's strict type.
         switch ($columntype) {