Grainstore

[] (http://travis-ci.org/CartoDB/grainstore)

Need to simply generate a Mapnik map from a dynamic PostGIS table?

Grainstore is an opinionated Carto MML style store for PostGIS tables, views or sql queries that outputs Mapnik XML stylesheets.

Map styles can be defined in the Carto map styling language or use default styles. The Carto styles are persisted and Mapnik XML output cached in Redis, making it a good choice for use in map tile servers.

The generated Mapnik XML stylesheet plugs directly into Mapnik or Mapnik based tile server to render a map and interactivity layer.

Grainstore is braindead simple:

1 db + 1 table/query + 1 style = 1 Mapnik XML stylesheet.

1 db + N queries + N styles = 1 Mapnik XML stylesheet.

Typical use

initialise grainstore with PostGIS DB and table name
generate Mapnik XML for table with default styles
set custom style with carto
get carto errors returned if present, else store style
generate Mapnik XML with custom style
initialise with PostGIS DB, table name and sql query
generate Mapnik XML with stored style for table name and sql query

For using multiple layers use an array type for the 'sql' parameter and for the 'style' parameter. Each resulting layer will be named 'layerN' with N starting from 0 (needed to properly reference the layers from the 'style' values).

Install

npm install

Dependencies

node.js (tested from 0.4.x to 0.10.x)
npm
Redis
libosr (or libgdal)

Additional test dependencies

libxml2
libxml2-devel

Examples

var GrainStore = require('grainstore');


// fully default.
var mmls = new GrainStore.MMLStore();
var mmlb = mmls.mml_builder({dbname: 'my_database', table:'my_table'}, function(err, payload) {
	mmlb.toXML(function(err, data){
	  console.log(data); // => Mapnik XML for your database with default styles
	}); 
});


// custom redis and pg settings.
var mmls = new GrainStore.MMLStore({host:'10.0.0.1'}); 

var render_target = {
  dbname: 'my_db', 
  table:'my_tb', 
  sql:'select * from my_tb where age < 100'
}

// see mml_store.js for more customisation detail 
var mapnik_config = {
  Map: {srid: 4326},
  Datasource: {
    user: "postgres",
    geometry_field: "my_geom"
  }   
}

mmlb = mmls.mml_builder(render_target, mapnik_config, function(err, payload) {
	mmlb.toXML(function(err, data){
	  console.log(data); // => Mapnik XML of custom database with default style
	}); 
});



// custom styles.
var mmls = new GrainStore.MMLStore();
var mmlb = mmls.mml_builder({dbname: 'my_database', table:'my_table'},
function(err, payload)
{
	var my_style = "#my_table{marker-fill: #FF6600;}"

	mmlb.setStyle(my_style, function(err, data){
	  if err throw err; // any Carto Compile errors
	  
	  mmlb.toMML(function(err, data){
	    console.log(data) // => Carto ready MML
	  }); 
	  
	  mmlb.toXML(function(err, data){
	    console.log(data); // => Mapnik XML of database with custom style
	  }); 
	  
	  mmlb.getStyle(function(err, data){
	    console.log(data); // => "#my_table{marker-fill: #FF6600;}"
	  });
	});
});

For more examples, see the tests.

Tests

To run the tests, from the project root:

npm test

TODO

make storage pluggable

to release: npm publish

strk/grainstore