Search code examples
yamlopenmaptiles

exclamation marks around a string in yaml

In a yaml config file created by OpenMapTiles I found the following syntax:

table: (SELECT geometry, class FROM layer_water(!bbox!, z(!scale_denominator!)))

The strings enclosed in exclamation marks obviously will be substituted by some provided values. My question is, how would this be done? I did not find anything about such a syntax for variable substition in yaml. Can someone please point me in the right direction? Or is this meant to be dealed with AFTER parsing yaml?

Regards Oliver

Solution

  • I found it. The syntax is special to Mapnik and in my case to the PostGIS Plugin. The PostGIS plugin supports several special tokens. You can use them in subqueries and Mapnik will replace them at render time.