Turning WKB type integer into text for memory layer creation with PyQGIS

Question

I'm creating a memory layer in PyQGIS and I need to match the geometry of the memory layer that I am building to the geometry of another layer.

After some investigation it seems to me that, as per QGIS 2.2 Documentation and the QGIS 2.2 API Documentation, the URI defining the geometry type approximately matches the QGis::WkbType member enumeration text.

I know I can easily query the WKBType of my input layer with

myWkbType = mylayer.dataProvider().geometryType()

However, this returns an integer, whereas the constructor requires text. Is there a simple built-in PyQGIS way to turn these constants into text, or do I need to build a hacky little reverse mapping function for it?

Answer 1

Since QGIS 3.0 you can use the displayString and geometryDisplayString functions:

>>> QgsWkbTypes.displayString(layer.wkbType())
'MultiSurface'

>>> QgsWkbTypes.geometryDisplayString(layer.geometryType())
'Polygon'

Answer 2

QGis.WkbType is a sip wrapped enum class which doesn't have a reverse mapping function like it would if it were a native python enum.

So the answer i guess would be either to wrap the class in another class with the desired python enum attributes or to write a hacky little lookup function.

Rather than all the drama of writing a wrapping class - here's a stand alone dictionary and reverse map:

my_WkbType = { 'WKBUnknown': 0, 'WKBPoint':1, 'WKBLineString':2, 'WKBPolygon':3, 'WKBMultiPoint':4, 'WKBMultiLineString':5, 'WKBMultiPolygon':6, 'WKBNoGeometry':7, 'WKBPoint25D':8, 'WKBLineString25D':9, 'WKBPolygon25D':10, 'WKBMultiPoint25D':11, 'WKBMultiLineString25D':12, 'WKBMultiPolygon25D':13 }

my_rev_WkbType = {v:k for k, v in my_WkbType.items()}

To test it you can try:

my_rev_WkbType[QGis.WKBPolygon]

Or in the context of the question:

my_rev_WkbType[mylayer.dataProvider().geometryType()]

Answer 3

this post is quite old, just stumbled upon it. To get a text representation to all available WkbTypes, i ended up using this:

dict([(v, k) for k, v in QgsWkbTypes.__dict__.items() if isinstance(v, int)])