Le jeudi 24 janvier 2013 22:54:48, Jason Greenlaw - NOAA Affiliate a écrit : > When loading into a PostgreSQL/PostGIS database, can the VRT/CSV driver > convert missing values (for a "Real" field) to NULL instead of defaulting > to 0.00? > > Example: > > I'm attempting to load a CSV file into PostgreSQL using the following > simple VRT file: > > -------------------------------------------------------- > <OGRVRTDataSource> > <OGRVRTLayer name="sfcdump"> > <SrcDataSource relativeToVRT="1">sfcdump.csv</SrcDataSource> > <GeometryType>wkbPoint</GeometryType> > <LayerSRS>WGS84</LayerSRS> > <GeometryField encoding="PointFromColumns" x="longitude" > y="latitude"/> > <Field name="stnid" src="stnid" type="String"/> > <Field name="latitude" src="latitude" type="Real"/> > <Field name="longitude" src="longitude" type="Real"/> > <Field name="td" src="td" type="Real"/> > <Field name="t" src="t" type="Real"/> > </OGRVRTLayer> > </OGRVRTDataSource> > -------------------------------------------------------- > > Some of the records do not have any value for the "td" column; for example, > this single-record CSV: > > -------------------------------------------------------- > stnid,lat,lon,td,t > KOVE,39.490002,-121.620003,,283.0019 > -------------------------------------------------------- > > When records such as these are loaded into the database using ogr2ogr, the > missing value becomes 0.00 rather than NULL. > > Is this expected behavior? Is there any way to tell the VRT/CSV driver how > to handle missing/null values for numeric fields? > > Additionally, I've noticed that blank/missing values for String columns get > imported as empty strings rather than NULL (but perhaps that's the expected > behavior in this case).
Try creating a sfcdump.csvt file with the following line : String,Real,Real,Real,Real This way the CSV driver will have the correct type right at the source and will report a null real value, instead of a blank string that the VRT driver currently converts into 0. As far as blank values in CSV being imported as empty string, I'm not sure there's a perfect choice on that. You can always update your database table to replace empty string by null if that's what fits more your purpose. > > Thanks, > Jason _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
