Update optional-conditions.md

Author: rkrx

doc/optional-conditions.md

@@ -1,5 +1,7 @@
 # Optional conditions
 
+Sometimes you want to set conditions based on dynamic data. One example would be a grid-list with dynamic filters for certain columns. Following the example below, you can predefine _optional conditions_ which will execute when the corresponding data in the `$filter`-Array is present. 
+
 ```PHP
 $filter = [
 	'name' => 'Peter',
@@ -9,15 +11,13 @@ $filter = [
 	],
 ];
 
-$req = new RequiredFilterMap($filter);
-$opt = new OptionalFilterMap($filter);
-
 $query = $db
 ->from('t', 'test')
-->where($req('t.name=?', $filter, 'name'))
-->where($opt('t.date >= ?', $filter, 'date.start')) // Key in dot-notation
-->where($opt('t.date <= ?', $filter, ['date', 'end'])) // Array-Key
+->where(new DBExprFilter('t.name = ?', $filter, 'name'))
+->where(new DBExprFilter('t.date >= ?', $filter, 'date.start')) // Key in dot-notation
+->where(new DBExprFilter('t.date <= ?', $filter, ['date', 'end'])) // Key in array-notation
 ```
 
+You can also define validation rules to only match certain data in `$filter`.
 
 [Back](../README.md)