Fixed filter logic for exclusion of entities. Before parts with null values as property value were wrongly not shown

This fixes  issue #658

Author: jbtronics

src/DataTables/Filters/Constraints/EntityConstraint.php

@@ -137,7 +137,7 @@ public function apply(QueryBuilder $queryBuilder): void
         }
 
         //We need to handle null values differently, as they can not be compared with == or !=
-        if (!$this->value instanceof AbstractDBElement) {
+        if ($this->value === null) {
             if($this->operator === '=' || $this->operator === 'INCLUDING_CHILDREN') {
                 $queryBuilder->andWhere(sprintf("%s IS NULL", $this->property));
                 return;
@@ -152,8 +152,9 @@ public function apply(QueryBuilder $queryBuilder): void
         }
 
         if($this->operator === '=' || $this->operator === '!=') {
-           $this->addSimpleAndConstraint($queryBuilder, $this->property, $this->identifier, $this->operator, $this->value);
-           return;
+            //Include null values on != operator, so that really all values are returned that are not equal to the given value
+            $this->addSimpleAndConstraint($queryBuilder, $this->property, $this->identifier, $this->operator, $this->value, $this->operator === '!=');
+            return;
         }
 
         //Otherwise retrieve the children list and apply the operator to it
@@ -168,7 +169,8 @@ public function apply(QueryBuilder $queryBuilder): void
             }
 
             if ($this->operator === 'EXCLUDING_CHILDREN') {
-                $this->addSimpleAndConstraint($queryBuilder, $this->property, $this->identifier, 'NOT IN', $list);
+                //Include null values in the result, so that all elements that are not in the list are returned
+                $this->addSimpleAndConstraint($queryBuilder, $this->property, $this->identifier, 'NOT IN', $list, true);
                 return;
             }
         } else {

src/DataTables/Filters/Constraints/FilterTrait.php

@@ -56,15 +56,25 @@ protected function generateParameterIdentifier(string $property): string
 
     /**
      * Adds a simple constraint in the form of (property OPERATOR value) (e.g. "part.name = :name") to the given query builder.
+     * @param  QueryBuilder  $queryBuilder The query builder to add the constraint to
+     * @param  string  $property The property to compare
+     * @param  string  $parameterIdentifier The identifier for the parameter
+     * @param  string  $comparison_operator The comparison operator to use
+     * @param  mixed  $value The value to compare to
+     * @param  bool  $include_null If true, the result of this constraint will also include null values of this property (useful for exclusion filters)
      */
-    protected function addSimpleAndConstraint(QueryBuilder $queryBuilder, string $property, string $parameterIdentifier, string $comparison_operator, mixed $value): void
+    protected function addSimpleAndConstraint(QueryBuilder $queryBuilder, string $property, string $parameterIdentifier, string $comparison_operator, mixed $value, bool $include_null = false): void
     {
         if ($comparison_operator === 'IN' || $comparison_operator === 'NOT IN') {
             $expression = sprintf("%s %s (:%s)", $property, $comparison_operator, $parameterIdentifier);
         } else {
             $expression = sprintf("%s %s :%s", $property, $comparison_operator, $parameterIdentifier);
         }
 
+        if ($include_null) {
+            $expression = sprintf("(%s OR %s IS NULL)", $expression, $property);
+        }
+
         if($this->useHaving || $this->isAggregateFunctionString($property)) { //If the property is an aggregate function, we have to use the "having" instead of the "where"
             $queryBuilder->andHaving($expression);
         } else {