In QGIS 3 there are a number of useful vector tools available via GRASS functions. However, the output of many of these only contain 'cat' attribute in their output.
For example, if I run the routing tool v.net.allpairs, it outputs a number of routes in an input vector line layer that connect all the input points in an input vector point layer.
But since the only attribute in the output line routes are 'cat' and to and from 'cat', it's difficult to fetch attributes of the original input points (for example if I want to transfer a flow magnitude between two points in a network to the route line connecting them).
So, how do I best make sure that vector input to GRASS either keeps its original attributes in the output, or has unique id(s) that can be used to retroactively rejoin the original attributes?