Populating attribute table with the ID of the nearest point in QGIS

Question

I have two point layers, let's say one is 'endpoints' and another layer is 'nodes'.

The "endpoints" layer attribute table has a field called "nearest_node", I want to populate it with names/IDs of the nearest "node".

I have tried using the field calculator to build a proper query, however, I found no way to cycle through all "node" objects on a different layer to find the nearest point.

Is there some easy way to do it within QGIS?

Answer 1

An alternative way to do it would be to use the overlay_nearest function on a new field ("nearest_node") in your 'endpoints' layer.

overlay_nearest(
    layer:='nodes',    -- the name of your nodes layer
    expression:=$id,   -- e.g. the attribute you wish to get from the nearest feature
    limit:=1           -- limit the number of returned features to 1 (the nearest)
)[0]                   -- the [0] is to get the first (and in this case only - due to the limit) element of the resulting array

Answer 2

Basically, I use the "Distance to nearest hub (line to hub)" algorithm, then use the created temporary layer to use in an attribute calculation with the following query:

attribute(get_feature('NewLayer', 'matching_field', "matching_field"), 'HubName')

This does exactly what I want it to do, the above example uses different field names, so use what layers and field names you've got.

Afterwards, I can discard the layer created by the processing algorithm.