Autogenerate fields for 'point' layer to represent the lines 'ingress' and 'egress' from point

Question

I have a point layer named closure and a line layer named cable in QGIS.

Within closure there's 4 fields (id, type, ingress, egress), cable has 4 fields (id, type, from, to).

I have managed to form a code within attribute form to tell me that cable starts at closure Point A (from will show me closure type):

aggregate(layer:='closures_v1', aggregate:='max', expression:="type",
filter:= intersects( $geometry, start_point(geometry(@parent))))

and ends at closure Point B (to will show me closure type):

aggregate(layer:='closures_v1', aggregate:='max', expression:="type",
filter:= intersects( $geometry, end_point(geometry(@parent))))

Though I have not been able to autogenerate the fields for the closure layers' columns ingress and egress. ingress will represent the cable that is entering the closure (there can only be one), egress will represent the cable that is exiting the closure (there can be multiple). The autogenerated field will tell me the cable type.

Is this possible?

Let’s says I had one closure point called 'main closure', I will draw a cable (whatever I decide to label it, in this called 'cable IN') to end at the 'main closure' --- this will be my ingress cable.

Then, I draw two cables starting from the 'main closure'(I will label these 'cable out1' and 'cable out2').

I would like an automated process to auto-fill my ingress layer to tell me that 'cable IN' is the cable entering the 'main closure', and my egress layer to tell me that 'cable out1' and 'cable out2' are exiting 'main closure'.

Answer 1

To get the name (saved in field type) of the feature from the layer cable that enters the current point, use the expression below the screenshot. Use a virtual field to autogenerate the values. Like this, the value is updated automatically each time you change something.

Screenshot: the expression, used here as source of a dynamic label:

array_filter (
    array_foreach(
        overlay_nearest ('cable', $id, limit:=-1),
        if (
            intersects (
                end_point (geometry (get_feature_by_id('cable',@element))),
                buffer ($geometry,0.01)
            ),
            attribute (get_feature_by_id ('cable',@element), 'type'),
            ''
        )
    ),
    @element <>''
)[0]

To get the name of the outgoing cables, replace end_point in line 6 with start_point and enclose the whole expression as argument in a array_to_string() function, pseudocode: array_to_string( [expression_from_above_changed_to_start_point])