How to join point attribute to polyline layer?

Question

I have a polyline layer in rectangular shapes representing boundaries. These polylines are adjacent to one another. I also have a point layer with the name of the boundary centered within the polyline. I want to join the 'boundary name' attribute field in the point layer to the boundary polyline the point is within. My method to accomplish this was to polygonize the polyline layer and join the point attributes using the 'within' criteria. However, when attempting to polygonise the polyline layer, the FID of the polyline layer is not retained and the new polygons are assigned new FID's which I was hoping to retain so I could join the data to the original polylines. How would I accomplish joining a text field in a point layer to a polyline layer?

qgis version 3.10.14

Answer 1

You could make a new column and paste your old FIDs of the polylines' Boundary Name in that column, call it something like "line_id".

Then, when polygonising the line_id column would be maintained. After spatially joining the point data to the polygon, you can join the data to the polyline using the line_id column as join ID/Key.