Export as DGN with QgsVectorFileWriter.writeAsVectorFormat

Question

This code works in QGIS 2.14 but not in 2.18. What do I have to change to be able to export properly to DGN. From what I understand, now it tries to save in microstation V8 format instead of v7.

I don't want to use "convert format" from the processing tool box, I'd really like to save directly to DGN without intermediary steps.

QgsVectorFileWriter.writeAsVectorFormat(
    couche_source,   #loaded layer
    enregistre_sous, #path to save as
    'utf8',
    QgsCoordinateReferenceSystem(2950, QgsCoordinateReferenceSystem.EpsgCrsId),
    'DGN',
    False,
    None,
    skipAttributeCreation = True,
    )

​I really don't know what to do, and I didn't find anything helpful to me.

Even when I try to save as DGN directly form QGIS it doesn't work. I get this error message :

Export to vector file failed.
Error: creation of layer failed (OGR error:creation option '' is not formatted with the key=value format)

And I did not modify anything in the options.

Answer 1

When I use the parameter 'DGN' as 'dgn', it successfully exports as DGN file in QGIS 2.18.22.

QgsVectorFileWriter.writeAsVectorFormat(
    couche_source,
    enregistre_sous,
    'utf8',
    QgsCoordinateReferenceSystem(2950, QgsCoordinateReferenceSystem.EpsgCrsId),
    'dgn', ### change 'DGN' into 'dgn'
    False,
    None,
    skipAttributeCreation = True
    )