Adding attributes of points to attribut table of lines in QGIS

Question

I'm using QGIS 3.8 with GRASS 7.6.1

I want to add only the names of my vertices (from line intersection, duplicates deleted) to the attributtable of my lines (like start and end node). Every line has only two vertices.

What I tried:

• geom_to_wkt(start_point($geometry)) --> gives me the coordinates (I need the name) of my real nodes not of the vertices

• "add by position" only transfers the name of one vertices (but I need both)

Answer 1

In QGIS there is a possibility using a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer...

Let's assume there are two layers 'points_layer' (red) and 'lines_layer' (grey) respectively, see image below.

With the following query, it is possible to add only the names of my vertices (from line intersection, duplicates deleted) to the attributes table of my lines (like start and end node).

SELECT
    l.*,
    p1.Info AS start_point_info,
    p2.Info AS end_point_info
FROM
    "lines_layer" AS l
LEFT JOIN
    "points_layer" AS p1
    ON st_equals(start_point(l.geometry),p1.geometry)
LEFT JOIN
    "points_layer" AS p2
    ON st_equals(end_point(l.geometry),p2.geometry)

The output Virtual Layer will look like as following

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References:

• Understanding Join Attributes by Location in QGIS?