Add hint to NULL query

der-stefan 2014-01-02 06:17:31 -08:00
parent 0c795e198b
commit b19e083165

@ -21,12 +21,17 @@ And they can be combined in complex rules using brackets: `(` and `)`.
Attributes can be compared against [Regular expressions](http://en.wikipedia.org/wiki/Regular_expression) using the `.match` operator.
## Examples in XML
Matches all Objects that have an attribute "amenity" with a value of "restaurant":
Matches all objects that have an attribute "amenity" with a value of "restaurant":
```xml
<Filter>[amenity] = 'restaurant'</Filter>
```
Match if a value is NULL:
```xml
<Filter>[amenity] = 'restaurant' and not ([name] = null)</Filter>
```
NEW in Mapnik 2.1.x: Matches all features that contain point geometries:
```xml