topic Re: Converting Lat/Long Coordinates in JSON Feed to Geometry in ArcGIS GeoEvent Server Questions

Converting Lat/Long Coordinates in JSON Feed to Geometry

TomFlahive — Tue, 13 May 2014 18:40:19 GMT

I have a JSON feed which contains the Latitude/Longitude coordinates of a point feature in a format that makes it harder to get at. The part of the JSON record that has the Lat/Long looks like this:

{
    "location": {
        "type": "point",
        "coordinate": [
            34.854503,
            -117.087665
        ]
    }
}

And the GeoEvent Definition File that is auto-generated looks like this:

[ATTACH=CONFIG]33786[/ATTACH]

Does anyone know how these coordinates can be extracted to create the Geometry for this event? My end goal is to generate a feature service from the JSON data.

Thanks.
Tom

Re: Converting Lat/Long Coordinates in JSON Feed to Geometry

RJSunderman — Thu, 15 May 2014 02:31:34 GMT

Hello Tom -

The screenshot you took of the GeoEvent Definition generated by the inbound connector is indicating that location is a group containing two elements. The first element type is a String, the second element coordinate is a list of Double values. The "infinity" is how GEP indicates an element whose cardinality is "many".

When coordinates are in a list, you need to specify the list index from which the coordinate value can be obtained. In your example you would retrieve the X Geometry Field from location.coordinate[1] and the Y Geometry Field from location.coordinate[0]. Note that I'm assuming the value 34.854503 is "latitude" and the value -117.087665 is "longitude". The list index is zero-based.

Please refer also to the forum thread Is" rel="nofollow" target="_blank">http://forums.arcgis.com/threads/109508-Is-there-an-expression-for-converting-values-of-longtitude-and-latitude-into-a-point]Is there an expression for converting values of longtitude and latitude into a point.

Hope this information helps -
RJ

Re: Converting Lat/Long Coordinates in JSON Feed to Geometry

TomFlahive — Fri, 16 May 2014 21:38:59 GMT

That worked, thanks! I added the coordinates to my "Poll an external website for JSON" input.

[ATTACH=CONFIG]33887[/ATTACH]

I am now able to generate features from the JSON feed to an "Update a Feature" output. Works nicely.

Tom
LSA Associates