[GRASS-user] v.out.ogr and Date fields

[Markus Metz]

On Wed, Nov 6, 2019 at 4:52 PM Markus Metz <markus.metz.giswork at gmail.com>
wrote:
>
>
>
> On Wed, Nov 6, 2019 at 3:01 PM Markus Neteler <neteler at osgeo.org> wrote:
> >
> > Hi Daniel,
> >
> > On Mon, Nov 4, 2019 at 12:23 PM Daniel McInerney
> > <daniel.o.mcinerney at gmail.com> wrote:
> > >
> > > Hi List,
> > >
> > > As part of a workflow, we are importing ESRI Shapefiles into GRASS so
> > > that we can manage the vector topology, before re-exporting the
vectors
> > > back to an ESRI Shapefile. However, we noticed that the date fields
are
> > > being converted from a field of type Date to type String.
>
> Indeed, this happens in v.out.ogr, should be easy to fix. Can you create
a ticket just as a reminder?

Please try https://github.com/OSGeo/grass/pull/184

Markus M
> >
> > AFAIK this is how SQLite handles it internally but the GRASS DBMI
> > driver should take care of it to keep it in date format.
>
> This has nothing to do with the sqlite driver.
>
> Markus M
>
> >
> >
> > > Hopefully the
> > > following steps will demonstrate the issue:
> > >
> > > The input Shapefile is scdb_date, with a date field called 'BA_DATE':
> > >
> > >  >ogrinfo -so -al scdb_date.shp | grep BA_DATE
> > > BA_DATE: Date (10.0)
> > >
> > > After importing into GRASS using v.in.ogr, the field is still of type
> > > DATE (although the length has increased to 20):
> > >
> > >  >db.describe scdb_date | grep -A 5 BA_DATE
> > > column:BA_DATE
> > > description:
> > > type:DATE
> > > len:20
> > > scale:0
> > > precision:0
> > >
> > > However, when I export the vector (scdb_date) back to an ESRI
Shapefile
> > > using v.out.ogr, the BA_DATE is converted to a String:
> > >
> > > v.out.ogr input=scdb_date output=scdb_date_export.shp
> > > format='ESRI_Shapefile'
> > >
> > >  >ogrinfo -so -al scdb_date_export.shp | grep 'BA_DATE'
> > > BA_DATE: String (20.0)
> >
> > Probably the date detection failed in the grass-sqlite driver?
> > Could it be an encoding problem?
> >
> > > I tried exporting to a GeoPackage, but the issue persists. While, we
can
> > > still overcome this issue using ogr and SQL, I am wondering if is
there
> > > a flag or option in v.out.ogr that I am overlooking that would
maintain
> > > the fields of type Date or is there something else that I should
consider?
> >
> > As this is unexpected could you make a small data sample available to
> > easier reproduction?
> >
> > thanks
> > Markus
> > _______________________________________________
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> > grass-user at lists.osgeo.org
> > https://lists.osgeo.org/mailman/listinfo/grass-user
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