[Qgis-developer] GDAL 2.1 can update Geojson files - What is missing in QGIS to edit GeoJSON files ?

[kimaidou]

Hi all

I have just tested QGIS master build againt GDAL "trunk" (build via a git
clone from GDAL github repository & following the doc instructions [1] ).
It works like a charm with a small roads dataset.

Thanks Even (and other involved devs and funders ) for making this happen !

I have seen one first caveat :

* Export a Shapefile to GeoJSON in QGIS via the "Save as" and choose to
keep only 1 number for decimal precision
* Open this GeoJSON file, toggle edition, and add a new feature
* The new feature geometries are written with default decimal precision
(for example : 6790978.453365888446569 ) and not like the other original
features ( for example : 6790978.4 )

We should have a way in QGIS to keep the original decimal precision. Any
clue on this ? Should I open a ticket ?

Regards
Michaël

[1] https://trac.osgeo.org/gdal/wiki/BuildingOnUnix


2016-01-14 20:57 GMT+01:00 Even Rouault <even.rouault at spatialys.com>:

> Le jeudi 14 janvier 2016 20:38:04, Nyall Dawson a écrit :
> > On 15 Jan 2016 2:39 AM, "Even Rouault" <even.rouault at spatialys.com>
> wrote:
> > > A more "streaming-like" approach for the driver not proceeding to full
> > > ingestion of features could be desirable to remove that limitation, but
> >
> > that's
> >
> > > more involved. A possibility could be to have a "at-hand" parser to
> >
> > delimitate
> >
> > > JSon "Feature" objects and use only json-c to parse each feature. But
> >
> > GeoJSON
> >
> > > is certainly not the more appropriate file format to deal with huge
> >
> > datasets...
> >
> >
> > Even,
> >
> > Editable GeoJSON in OGR is great news!
> >
> > I've got a question regarding the geojson driver you may be able to
> assist
> > with. Is there any method in the OGR libraries which allow direct parsing
> > of a string to a  layer? (Ie, without first writing it out to a file).
> >
> > I'd like to add the ability to directly paste geojson text into QGIS and
> > have it inserted as a feature in the current layer (like how you can
> > currently paste WKT text as a feature). I don't want to have to manually
> > parse the json (that would be a nightmare).
>
> Well, the GeoJSON driver support "filenames" which are in fact GeoJSON
> content:
>
> $ ogrinfo
> '{"type":"Feature","properties":{"foo":"bar"},"geometry":{"type":"Point","coordinates":[2,49]}}'
> -ro -al
>
> Layer name: OGRGeoJSON
> Geometry: Point
> Feature Count: 1
> Extent: (2.000000, 49.000000) - (2.000000, 49.000000)
> Layer SRS WKT:
> GEOGCS["WGS 84",
>     DATUM["WGS_1984",
>         SPHEROID["WGS 84",6378137,298.257223563,
>             AUTHORITY["EPSG","7030"]],
>         AUTHORITY["EPSG","6326"]],
>     PRIMEM["Greenwich",0,
>         AUTHORITY["EPSG","8901"]],
>     UNIT["degree",0.0174532925199433,
>         AUTHORITY["EPSG","9122"]],
>     AUTHORITY["EPSG","4326"]]
> foo: String (0.0)
> OGRFeature(OGRGeoJSON):0
>   foo (String) = bar
>   POINT (2 49)
>
> Works also with FeatureCollections.
> Alternatively, you could also put the content in a in-memory GDAL file
> (/vsimem/ virtual file system) and open it.
>
> So you could likely instanciate a temporary layer and get a QGIS feature
> from that.
>
>
> If you are just interested in geometries and not attributes, there's also
> the C function :
>
> OGRGeometryH    OGR_G_CreateGeometryFromJson (const char *);
>
>
> >
> > If I could somehow take advantage of OGR's geojson driver to do the heavy
> > lifting then this work would be trivial.
> >
> > Any ideas?
> >
> > Nyall
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com
> _______________________________________________
> Qgis-developer mailing list
> Qgis-developer at lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-developer
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-developer
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20160115/53a7fbbb/attachment-0001.html>