format geojson from postgis

Question

I am trying to build a GeoJSON object from a SQL query to some GIS point data in a postgis postgresql database. A snippet of my node.js app.js is below.

As it stands I understand building the type and features, but don't know how to attach a properties array to each GeoJSON record (in the below, it all renders at the end, separate from (not collated with) the features).

THE QUESTION: What do I need to do so that the properties attach (collate) for each record in the loop that builds the GeoJSON So that it looks more like this http://www.geojson.org/geojson-spec.html#examples?

`function GrabData(bounds, res){

  pg.connect(conn, function(err, client){

  var moisql = 'SELECT ttl, (ST_AsGeoJSON(the_geom)) as locale from cpag;'


  client.query(moisql, function(err, result){
    var featureCollection = new FeatureCollection();

    for(i=0; i<result.rows.length; i++){
      featureCollection.features[i] = JSON.parse(result.rows[i].locale);
      featureCollection.properties[i] = JSON.parse(result.rows[i].ttl); //this is wrong
   }

   res.send(featureCollection);
   });

});
}

 function FeatureCollection(){
   this.type = 'FeatureCollection';
   this.features = new Array();
   this.properties = new Object;  //this is wrong
 }

`

Answer 1

This should do the job:

...
for(i=0; i<result.rows.length; i++){
    var feature = new Feature();
    feature.geometry = JSON.parse(result.rows[i].locale);
    feature.properties = {"TTL", result.rows[i].ttl};
    featureCollection.features.push(feature);
}
...

Using:

function FeatureCollection(){
    this.type = 'FeatureCollection';
    this.features = new Array();
}

function Feature(){
    this.type = 'Feature';
    this.geometry = new Object;
    this.properties = new Object;
} 

Answer 2

I recently wrote a little helper module for this purpose. It's very straightforward to use -

var postgeo = require("postgeo");

postgeo.connect("postgres://user@host:port/database");

postgeo.query("SELECT id, name ST_AsGeoJSON(geom) AS geometry FROM table", "geojson", function(data) {
    console.log(data);
});

You can find the repo here - https://github.com/jczaplew/postgeo