[QGIS-Developer] set and export FID with OGR provider

[G. Allegri]

PS: QGIS server adds the id when creating the GeoJSON for a GetFeature
request [1].

giovanni

[1]
https://github.com/qgis/QGIS/blob/master/src/server/services/wfs/qgswfsgetfeature.cpp#L994

Il 9 ott 2017 18:13, "G. Allegri" <giohappy at gmail.com> ha scritto:

> HI all,
> GeoJSON RFC7946 states that "If a Feature has a commonly used identifier,
> that identifier SHOULD be included as a member of the Feature object with
> the name "id", and the value of this member is either a JSON string or
> number". For example OpenLayers tries to parse the id field to uniquely
> identify the features inside a GeoJSON feature collection.
> I've digged how OGR GeoJSON driver treats FIDs during serialization and it
> seems that it will write it if the OGrFeature has the FID field set [2],
> but AFAICS QIGS OGR provider doesn't set it unless "the first attribute
> is the FID and the user has set it". Well, this condition depends on [4],
> and now I odn't understand how this applies to a QGIS layer being exported
> to GeoJSON.
>
> Questions:
>  - is there a way to force the OGR provider setting the FID?
>  - could the OGR provider have an option to force it from the export
> window, like Mapserver does with the USE_FEATUREID option for its output
> format
>
> *?*
> giovanni
>
> [1] https://tools.ietf.org/html/rfc7946#page-11
> [2] https://github.com/OSGeo/gdal/blob/trunk/gdal/ogr/ogrsf_frmts/geojson/
> ogrgeojsonwriter.cpp#L601
> [3] https://github.com/qgis/QGIS/blob/master/src/providers/ogr/
> qgsogrprovider.cpp#L1269
> [4] https://github.com/qgis/QGIS/blob/master/src/providers/ogr/
> qgsogrprovider.cpp#L894
> [5] http://mapserver.org/output/ogr_output.html#table-of-contents
>
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