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I need to create a standalone DBF file with some features. I know how to add the fields but I'm not able to add features and to create only a standalone DBF, without any other files such as .shp or .prj. I've tried creating a LineString in memory and then writing it with QgsVectorFileWriter, using ESRI Shapefile as driver, but it creates a simple shapefile with no features. The GDAL docs say that it can manage standalone DBF but I'm struggling with it and I can't find the way to do it.

This is the code I tried to create it and the export it.

self.work_line_table = QgsVectorLayer('LineString', 'Line_table', 'memory')

[Code for adding fields]

# Add features using the attribute from another layer. It's not working
self.work_line_table.startEditing()
for line in self.work_line_layer.getFeatures():
    line_id = line['IdLinia']
    feature = QgsFeature()
    feature.setAttributes([line_id, self.municipi_codi_ine])
    self.work_line_table.dataProvider().addFeatures([feature])

self.work_line_table.commitChanges()

# Export the table
QgsVectorFileWriter.writeAsVectorFormat(self.work_line_table,
                                        os.path.join(GENERADOR_WORK_DIR, 'MM_LiniesTaula.dbf'),
                                        'utf-8', self.crs, 'ESRI Shapefile')

I've thought in creating it as shapefile and then removing all the other files associated to it except the DBF file, but anyway I can't add any feature to the DBF.

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  • I've fixed the issue that I could not add features to the shapefile: it was because I wasn't adding any type of geometry to each feature. All that I had to do is to add an empty geometry such as feature.setGeometry(QgsGeometry.fromWkt('LineString()')). Anyway, I still can't manage or export a standalone DBF file.
    – Fran Martin Rivas
    Apr 27, 2021 at 10:44
  • 1
    When adding features to the layer using dataProvider() , you don't need to use startEditing() and commitChanges(). You can remove those two lines.
    – Kadir Şahbaz
    Apr 27, 2021 at 11:02

1 Answer 1

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Not sure why you expect a standalone DBF. By default, if you export to a DBF file, you will lose the geometry along the transformation. You may transform the geometry as an "ordinary" attribute e.g like a WKT geometry column to keep the info (in your case line.geometry().asWkt() is a way to get it)

You can find below a standalone recipe to do the job to export to DBF from an existing layer. It will create only a DBF with a CPG file (useful to know the encoding but not used by tools like LibreOffice or Excel, only by tools using OGR/GDAL behind the scene). Adapt it to your case.

layer = iface.activeLayer()
project = QgsProject.instance()
contextProject = project.transformContext()

optionsDbf = QgsVectorFileWriter.SaveVectorOptions()
optionsDbf.driverName = 'DBF file'
QgsVectorFileWriter.writeAsVectorFormatV2 (
    layer,
    '/tmp/myfile.dbf',
    contextProject,
    optionsDbf
)
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