tilestrata-postgis-geojson-tiles

Tilestrata plugin for generating geojson tiles from postgis.

Configuration

• geometryField (string, required): name of column containing geometry. (default = "geom")
• sql (function, required): method that returns a PostGIS query that will be executed. Be sure to protect against sql injection if doing dynamic filtering based on the request query string. The query can contain the following tokens:
  • {bbox} (box2d): the buffered tile bounding box
  • {geojson} (text): the geojson representation of the clipped and simplified geometry as text
• pgConfig (object, required): postgres connection options
  • {host} (string)
  • {password} (string)
  • {user} (string)
  • {port} (string)
  • {database} (string)
• simplifyFactor (number, optional): a constant affecting how much the geometry is simplified. (default = 0.75)
• buffer (number, optional): the amount of buffer around each tile in pixels. (default = 16)
• collectGeometry (boolean, optional): bundle all geometries together into a single geometry with ST_Collect before converting to GeoJSON. (default = false)
• mergeMultiLineStrings (boolean, optional): whether to try merging MultiLineStrings with ST_LineMerge before converting to GeoJSON. (default = false)
• dumpGeometry (boolean, optional): whether or not to use ST_Dump to break apart geometry collections. (default = false)

Example

var tilestrataPostGISGeoJSON = require('tilestrata-postgis-geojson-tiles');
var querystring = require('querystring');

var layer = server.layer('geojson-tiles', {minZoom: 5, maxZoom: 14});

// .../geojson-tiles/tile.json?id=12345
layer
  .route('tile.json')
    .use(headers({
      'Access-Control-Allow-Origin': '*'
    }))
    .use(tilestrataPostGISGeoJSON({
      geometryField: 'geom',
      sql: function(server, req) {
        var qs = querystring.parse(req.qs);
        var id = qs && qs.id ? parseInt(qs.id, 10) : null;

        return 'SELECT id, name, {geojson} FROM tablename WHERE ST_Intersects(geom, {bbox}) AND id = ' + id;
      },
      pgConfig: {
        username: 'postgres',
        password: 'password',
        host: 'localhost',
        port: '5432',
        database: 'postgres'
      }
    }));