GeoServer has a GeoJson encoder for complex features:
https://github.com/nmco/geoserver/blob/c3adc90120b8cb9e564d1c2eba564eaf47e82c0d/src/wfs/src/main/java/org/geoserver/wfs/json/ComplexGeoJsonWriter.java#L421
Not sure how helpful it would for you :)
On 03/16/2018 01:55 PM, Jesper Steen Møller wrote:
Hi Justin, Andrea and ilist,
On 16 Mar 2018, at 13.13, Justin Deoliveira <[email protected]
<mailto:[email protected]>> wrote:
I’m the original author of most of that code, but as Andrea states I haven’t had the time to be a
decent maintainer of it, so definitely go ahead with your improvements, having support for “deep”
or “complex” properties would be great. That module is fair game!
:-)
A word of warning: the way the parser is implemented it has some limitations and complexities.
It’s a purely streaming based parser that looks a lot like the XML sax interfaces, and because of
that and the way it manages state can be brittle and very dependent on how things are ordered in
a JSON document. I think there are a handful of tickets open with regard to ordering of properties.
Yep, I think I get the general idea of how things fit together. Not being able to specify the
order of properties in a JSON document makes it tough to read it in a streamy fashion, I don't
think there's much to do about it, in general. The GeoJSON spec specifically states that the order
of name/value pairs does not matter, as per the JSON RFC, whereas the newer ECMA-404 standard for
JSON states "These are all semantic considerations that may be defined by JSON processors or in
specifications defining specific uses of JSON for data interchange.".
One of the things I wanted to do in that module was re-implement it in a way that was more of a
hybrid streaming approach where the only time we “stream" is when it’s required (for feature
collections) and for most other objects just load everything into a map/list like data structure
before parsing it to a feature, geometry, etc… Unfortunately no such time do that has presented
itself :)
I know the feeling!
I won't be able to make significant architectural changes, but I'll see what I can do about the
nested/complex properties, and their interaction with the schema.
Also, I'm specifically not addressing nested features at the moment.
-Jesper
On March 16, 2018 at 5:47:02 AM, Andrea Aime ([email protected]
<mailto:[email protected]>) wrote:
On Fri, Mar 16, 2018 at 12:25 PM, Jesper Steen Møller<[email protected]
<mailto:[email protected]>>wrote:
Hi list
My use case for working with GeoJSON has hit upon a limitation in the
GeoJSON reader,
regarding "deep" objects in a Feature's properties. This is permitted by
the spec, but isn't
handled well in the deserializer (see GEOT-5158
<https://osgeo-org.atlassian.net/browse/GEOT-5158> andGEOT-4100
<https://osgeo-org.atlassian.net/browse/GEOT-4100>).
I'm guessing there's an issue in writing, too.
I'd be happy to prepare a PR for a generic handling of deep properties, using
either List<>
and Map<> or the appropriate JSON types, if you are interested.
I want to implement it in a way so that reading a GeoJSON containing deep
properties into
Features and serializing it back out would work without loss.
But first, I'd like to hear if any of the maintainers have any opinions
regarding such a change?
The gt-geojson module is in "unsupported", thus un-maintained.
I believe nobody will complain, but let's hear others :-)
Have any of the other formats similar "deep properties" - GML for instance?
GML nested properties have to abide to a schema, we have app-schema and associated GML encoder
support for that already.
But not for features having lists/maps inside, there is no support for it, and no way to build a
schema for them either right now.
Hope this helps.
Cheers
Andrea
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