Read a GeometryCollection from a string - openlayers-3

Question

in OpenLayers 3 I can read Features or a single Geometry from a GeoJSON string through an instance of ol.format.GeoJSON().
Example:
var parser = new ol.format.GeoJSON();
var arrOfFeatures = parser.readFeatures(geoJsonString);
//or
var usrGeom = parser.readGeometry(geoJsonString);
Now I have a string representing a GeometryCollection (not a MultiPoint, MultiLine or MultyPolygon, nor a FeatureCollection).
I cannot find a way to readGeometryCollection(GeoJSONstring) or something, having an ol.geom.GeometryCollection object as the result.
Can anyone help with this?
Thanks in advance.

Answer 1

Ok, the solution was to read a GeometryCollection just like any other Openlayers ol.geom.Geometry and then loop to read any single geometry, so: 1)read the string into a Geometry object, 2) if .getType() is "GeometryCollection" then loop the collection, and forEach(item) in the collection read the Geometry.
parseSingleGeometry : function(geometry, callback) {
switch (geometry.getType()) {
case 'MultiLineString':
geometry.getLineStrings().forEach(function (p) {
var newFeat = new ol.Feature({ geometry: p });
_features.push(newFeat);
});
break;
case 'MultiPolygon':
geometry.getPolygons().forEach(function (p) {
var newFeat = new ol.Feature({ geometry: p });
_features.push(newFeat);
});
break;
case 'Polygon':
case 'LineString':
case 'Point':
var newFeat = new ol.Feature({ geometry: geometry });
_features.push(newFeat);
delete newFeat;
break;
default:
break;
}
if (callback) { callback(); }
},
parseGeometryCollection: function(collection, callback) {
var ciccio = new ol.geom.GeometryCollection();
//ciccio.getType
var itemCount = ciccio.getGeometries().length;
var itemProg = 0;
ciccio.getGeometries().forEach(function (item) {
parseSingleGeometry(item, function () {
itemProg++;
if (itemProg == itemCount) {
if (callback) {
callback();
}
}
})
});
}
[...]
importGeoJson: function (geoJsonString) {
var parser = new ol.format.GeoJSON();
var projection = parser.readProjection(geoJsonString);
var usrProjCode = projection.getCode();
var convert = false;
if (usrProjCode != 'EPSG:3857') {
var msg = "The file provided is in the " + usrProjCode + " projection. The system supports the EPSG:3857 projection only.\n\rWe are converting your geometries in EPSG:3857.\n\rPlease visually check that the added shapes are what your file defines.";
alert(msg);
convert = true;
}
//if it's a feature or feature collection than I can readFeatures()
if (geoJsonString.indexOf("Feature") !== -1) {
console.log("reading feature(s)");
var arrOfFeatures = parser.readFeatures(geoJsonString);
arrOfFeatures.forEach(function (item) {
var usrGeom = item.getGeometry();
var newGeom = (convert) ? usrGeom.clone().transform(usrProjCode, 'EPSG:3857') : usrGeom;
if (newGeom.getType() == "GeometryCollection") {
_private.parseGeometryCollection(newGeom, function () { /*do something*/ })
}
else {
_private.parseSingleGeometry(newGeom, function () { /*do something*/ });
}
});
}
else { //otherwise work with geometries
var usrGeom = parser.readGeometry(geoJsonString);
var newGeom = (convert) ? usrGeom.clone().transform(usrProjCode, 'EPSG:3857') : newGeom;
if (newGeom.getType() == "GeometryCollection") {
_private.parseGeometryCollection(newGeom, function () { /*do something*/ })
}
else {
_private.parseSingleGeometry(newGeom, function () { /*do something*/ });
}
}
},
_features is the ol.Collection containing the features showed on the map.