From c6803838ab04b5266d6d0a2d07517a7740d51357 Mon Sep 17 00:00:00 2001
From: Frederic Junod <frederic.junod@camptocamp.com>
Date: Wed, 28 Oct 2015 14:55:43 +0100
Subject: [PATCH] Allow TopoJSON features with id equal to 0

---
 src/ol/format/topojsonformat.js      |  2 +-
 test/spec/ol/format/topojson.test.js | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/ol/format/topojsonformat.js b/src/ol/format/topojsonformat.js
index 1a4cdb87b8..c5c14b0b3e 100644
--- a/src/ol/format/topojsonformat.js
+++ b/src/ol/format/topojsonformat.js
@@ -260,7 +260,7 @@ ol.format.TopoJSON.readFeatureFromGeometry_ = function(object, arcs,
   var feature = new ol.Feature();
   feature.setGeometry(/** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(geometry, false, opt_options)));
-  if (object.id) {
+  if (object.id !== undefined) {
     feature.setId(object.id);
   }
   if (object.properties) {
diff --git a/test/spec/ol/format/topojson.test.js b/test/spec/ol/format/topojson.test.js
index 47f0ac7acd..df876986b0 100644
--- a/test/spec/ol/format/topojson.test.js
+++ b/test/spec/ol/format/topojson.test.js
@@ -22,6 +22,16 @@ var aruba = {
   ]
 };
 
+var zeroId = {
+  type: 'Topology',
+  objects: {
+    foobar: {
+      type: 'Point',
+      id: 0,
+      coordinates: [0, 42]
+    }
+  }
+};
 
 describe('ol.format.TopoJSON', function() {
 
@@ -60,6 +70,15 @@ describe('ol.format.TopoJSON', function() {
       ]);
     });
 
+    it('can read a feature with id equal to 0', function() {
+      var features = format.readFeaturesFromObject(zeroId);
+      expect(features).to.have.length(1);
+
+      var feature = features[0];
+      expect(feature).to.be.a(ol.Feature);
+      expect(feature.getId()).to.be(0);
+    });
+
   });
 
   describe('#readFeatures()', function() {