[Qgis-user] Relations capabilities

[Neumann, Andreas]

Hi Brent, 

The relations are a complicated topic and are being worked on. As you
have discovered, they are also still a bit limited in what you can do
with them until now. But I hope that is will change in the future. 

I can summarize a bit what you can do with them now: 

- embed linked/filtered tables in forms (I recommend you use it with the
drag and drop forms and put them in separate tabs) 

- you can add/delete features in related tables 

- for n:m you can also link/unlink records in related tables 

- for n:m there is a new mode now in 2.14 where you can hide the
in-between link table 

- in print composer in atlas context you can use it as a table source to
create data-sheets 

There may be more what you can do. I don't claim that my list is
complete. And of course different organizations have different
needs/requirements/ideas what they want to do with the relations. 

Now what you want to do (select/filter features in a related table based
on a selection in a related table) is not yet possible. I invite you to
specify exactly what you want and join the relations effort to improve
what you can do with relations in future QGIS versions. 

My organization has plans to have aggregate functions implemented on
related tables - things like count, sum, mean, min, max, concatenate,
etc. - to be used in tables or in the print composer (atlas context). 

Greetings, 

Andreas 

On 2016-02-24 02:16, Brent Wood wrote:

> Firstly, thanks to those who already helped me with this. 
> 
> I have established a relation between non-spatial catch records in a postgis table and a table of station information (linked via foreign key). 
> 
> If I click on a station with the info tool, I can see the various catch records from that station - so the relation is working. 
> 
> But that seems to be it. If I filter on the species in the catch, that only applies to the catch data showing up when I select a station - it does NOT hide stations where that species was not caught. I cannot change symbology based on a relation, I cannot select features based on a relation - all I can do is view the records - and with 70 fields in the station layer, the catch records are just a small window at the bottom of the form. 
> 
> It seems that to be useful I need to create the view or table in the database & access this with QGIS - whioch has issues for users without create access in the database - which is most of them. 
> 
> Is work on this area (relations) of QGIS actively ongoing, or should I look for non-QGIS approaches? 
> 
> Thanks, 
> 
> Brent Wood 
> 
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user

  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20160224/299bce7e/attachment.html>