esriJSON feature arrays not captured by parse() in arcgis.js

[abenrob]

Is this intentional?
When I point to an AGS JSON rest endpoint and try to parse to geoJSON, the object matches no cases and the geoJSON object remains empty.
If I limit to one feature (e.g. arcgis.features[0]) the conversion succeeds.

[patrickarlt]

@abenrob There is an explict reason we don't support this but do support converting single features. When you parse a feature into GeoJSON like

var geojson = Terraformer.ArcGIS.parse(arcgis.features[0]);

Does not produce valid GeoJSON because geojson.id is undefined. Valid GeoJSON Features must have a id property. Since converting an array of ArcGIS features to an array of GeoJSON Features would result in alot of invalud GeoJSON you should do this in a loop like this...

var FeatureCollection = {
  type: "FeatureCollection",
  features: []
}

for (var i = 0; i < arcgis.features.length; i++) {
  var feature = Terraformer.ArcGIS.parse(arcgis.features[i]);
  feature.id = i;
  FeatureCollection.features.push(feature)
};

If we allow passing an array we also open our selves up to bugs where mixed arrays of geometries and features are passed (which cant exist in GeoJSON) and would require us to sort them out into FeatureCollections or GeometryCollections.

[abenrob]

Thanks for the clarification.

[patrickarlt]

@abenrob fleshed out the explanation a little hit "Comment" to soon.

[jhobz]

I believe you have a typo in your explanation. The following line:

FeatureCollection.features.push(geojson)

should probably read

FeatureCollection.features.push(feature)

right?

[patrickarlt]

@jeffreyhobson Thanks, corrected it.

[jgravois]

hello from 2018!

in @esri/arcgis-to-geojson-utils we ultimately landed support for converting arrays of Esri JSON features into a GeoJSON FeatureCollection and auto-incrementing ids.

its also worth noting:

• RFC 7946 the id requirement was downgraded from a MUST to a SHOULD
• the Geoservices spec doesn't emit arrays of features with dissimilar geometries.

[hoogw]

@jgravois

can you show me example, how to do it?

---

in @esri/arcgis-to-geojson-utils we ultimately landed support for converting arrays of Esri JSON features into a GeoJSON FeatureCollection and auto-incrementing ids.

[jgravois]

@hoogw no need to respost the same question in three different places. i've answered you in Esri/arcgis-to-geojson-utils#30 (comment)