[Qgis-user] Using relations and transaction groups

[Rhys A.D. Stewart]

Hey Mathias,

Thanks!! That worked wonderfully well.

WRT the documentation, yes, I would say that it is poorly documented, but
is definitely something I would like to assist in rectifying. Just forked
qgis/QGIS-Documentation so hopefully, I can have a go at it on the weekend.

Rhys
Peace & Love | Live Long & Prosper


On Tue, Mar 3, 2020 at 1:18 AM Matthias Kuhn <matthias at opengis.ch> wrote:

> Hi Rhys,
>
> Ironically, this situation is exactly what transaction mode has been added
> for (to avoid the situation where someone clicks the save windows button
> before the save footprint button).
>
> The solution is not that obvious though (and might be poorly documented):
> Enable "deferred constraint checks" in your database and it will only check
> if foreign key constraints are ok at commit time (when you save it) and not
> while editing. If by any chance you get around to adding this information
> into the documentation, this will be much appreciated!
>
> Bests
>
> Matthias
> On 3/3/20 6:23 AM, Rhys A.D. Stewart wrote:
>
> Greetings All,
>
> I'm working with transaction groups and tables with relations (database
> foreign keys). Let's say that there are two tables, 'building_footprints'
> and 'windows'. The windows table references the 'building_footprints'
> table. I've added the relations in QGIS through the Project properties |
> relations dialog so that when editing 'building_footprints' I can add a
> child record for 'windows'. Now because I have transaction groups active,
> the changes are pushed back to the database immediately, if I create a
> child record before saving the parent record this causes a problem because
> the parent record doesn't exist. It is often the case that I am going to
> add child records when I'm creating the parent record, so adding a parent
> record, saving it, then editing it just to add the child record becomes
> cumbersome.
>
> I figured that someone must've had this issue before, but can't seem to
> find any documentation about this. Is there a workaround for this? (other
> than not using transaction groups and saving each layer individually)  Or
> have I just missed something extremely obvious?
>
>
> Rhys
> Peace & Love | Live Long & Prosper
>
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