I have two vector layers, one point layer named "element_ep", and another layer line named "reseau_ep".

In the layer "element_ep" there is a field 'nu_affaire' which contains the business number of each entity.

I want to retrieve this business number (from the field calculator) by creating a 'nu_affaire' field in the 'reseau_ep' layer.

The Qgis #refFunctions # plugin is well suited for this operation, but I want to get the code expression to get there.

Here are the layers and attribute tables.
[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/KUGCF.png