[QGIS-Developer] Probably a stupid python question regarding QgsVectorlayer

[Bo Victor Thomsen]

Hi list -

I have a (probably totally obvious, stupid) Pyhton question:

I need the datasource URI string of a maplayer chosen by the user.

I have found  the QgsMapLayer chosen by the user. And the QgsVectorLayer 
associated with the Maplayer.

How do I find the datasource string associated with the QgsVectorLayer?

There is oodles of QGIS information about generating a vector layer from 
a specific datasource. I need the opposite to generate a virtual layer 
in Python using a join between the chosen layer with a another 
predefined layer (which I have the datasource string for).

-- 

Med venlig hilsen / Kind regards

Bo Victor Thomsen