QGIS Joined Layer not displaying points visible on pre-join layer (No Extent)

Question

I have a shp file which is the output of the Toolbox Check validity tool in QGIS 3.4.3 The points display for me correctly but if I then join the layer with a csv attribute using the toolbox Join Attributes by Field Value to create a new layer the points no longer display on my map.

If I then select 1 of the features using the attribute table and use the zoom map to selected feature I get the error

Cannot zoom to selected feature No extent could be determined

I have also tried to associate the attribute table using the Layer properties Join but I end up in a similar position.

Looking at the layer properties it seems the extent value is lost in the processing but I'm not able to restore it using the "Update Extent" option on the Joined layer properties.

Anyone know how to solve my issue?

Updates

• I tried the multipart to single part suggested in the comments but that didn't work.
• Also if I try to filter the valid layer itself manually by creating a valid expression to only show the points with a specific value ColName in ('ID1') (which I know in the csv file) all the points disappear and I cannot zoom to the selected. This seems to me to point to an issue with my points layer not the join but not sure what.

Joined Layer

• Encoding windows-1258
• Geometry Point (MultiPoint)
• CRS EPSG:4326 - WGS 84 - Geographic
• Extent Empty
• Unit degrees
• Feature count 46

Valid Layer

• Encoding windows-1258
• Geometry Point (MultiPoint)
• CRS EPSG:4326 - WGS 84 - Geographic
• Extent -10.4506078999999996,51.4353689000000003 -6.0394994000000004,55.3615765999999994
• Unit degrees
• Feature count 4,735

Answer 1

I can think of two possible workarounds:

-Create new point layer, copy/paste features in it and Join Attributes by Field Value with csv.

-In your point layer, create new fields for your geometry with field calculator (X, Y): Join Attributes by Field Value with csv.

If you dont see points use Create Points Layer from table tool:

If any of this works, might be something wrong with Check validity tool and should be reported.

Answer 2

Today, just working on same scenario, similar (but not the same) issues.

I suspect the csv provider is not robust. Try converting your csv data to shapefile without geo attributes.

I'n my case, I spent some time to - create at *.csvt file to complement the *csv - clean the *.csv file of characters such as , ; " ' By clean I mean use libre office sheet to replace all with a space. And I'm still running with the csv.

A major clue, is that the number of attributes noted in your join layer is different to the number of attributes in your index layer. That was also evident in my situation.

Answer 3

Solution provided at the bottom using a virtual layer.

I had the same problem on a polygon layer dissolving polygons based on an attribute. I wanted to label NYC neighborhood table with borough name and not neighborhood name.

So not like this:

But like this:

The solution was to use a virtual layer for creating a point layer for labeling.

Using st_union resulted in Queens and Brooklyn not being label due to the error:

No extent could be determined

Using st_unaryunion solved the problem:

SELECT BORONAME, st_centroid(st_unaryunion(geometry)) as geometry /*:point:26918*/
FROM nyc_neighborhoods
GROUP BY BORONAME