All,
Thanks to Russel Mercer who corrected my logic - this works great, and
we'll be implementing this for several sets of map label placement! (see
response below).
Regarding Richard Greenwood's suggestion that we use geometry to store
the label placement - in theory and a bit of practice, the QGIS
x($geometry) / y($geometry) label placement expression values *do* work
for displaying labels - but QGIS doesn't allow you to move the labels
when they are assigned to the geometry x,y - so we would be moving the
feature itself, which doesn't lend itself to an intuitive label
placement workflow.
Added to that, what we're trying to do is build a table we use for
cartography that pulls from 3 separate tables - one of which will store
all the label placement properties for upwards of 8 printed maps, all at
various scales and sizes.
So for the time being, using LABEL_X, and LABEL_Y fields and updating
the properties using QGIS and editable views works great!
Thanks again everyone!
-Matt Baker
Denver, CO
On 9/16/2016 3:37 PM, Russell Mercer wrote:
Matt,
It looks like you are on the right track with your view and rules
setup. I think your primary issue may be that each of the rules is
trying to act on the view to do the insert, update, delete, as opposed
to acting on the underlying table.
For example, instead of this:
|--delete rulecreateorreplace
rule"delete_label"asondeletetoschools_district_map do instead
deletefromschools_district_map whereoid =old.oid; |
|Try this |
|--delete rule |
|create or replace rule "delete_label" as |
|on delete to schools_district_map do instead |
|delete from temp_schools_label |
|where oid = old.oid; |
This way, you are directing the delete command to redirect to the
underlying table instead of sticking with the view itself, which will
always be read only. If you change each of your rules to reflect the
same, you should have better luck.
Hope that helps,
Russell
On Fri, Sep 16, 2016 at 1:36 PM, Matthew Baker <mattba...@gmail.com
<mailto:mattba...@gmail.com>> wrote:
Hi all,
I've asked this on GIS.SE <http://GIS.SE>, to no avail:
I'd like to store label placement properties in a separate table,
build a view of the data I want to use for my map, and use QGIS to
move the labels manually. The idea is when the labels are updated,
the placement coordinates would go into the LABEL_X and LABEL_Y
fields in the label placement table, but the geometry of the
underlying points and several other attributes (coming from the
source tables) would remain unchanged.
However, when all is in place, QGIS throws the following error
when trying to save the edits to the view (the edit session can
start, labels moved, but cannot save):
|Could notcommitchanges tolayer schools_district_map
Errors:ERROR:1attribute value change(s)notapplied.Provider
errors:PostGIS error whilechanging attributes:ERROR:infinite
recursion detected inrules forrelation "schools_district_map" |||
Here is the definition of the view :
|CREATEORREPLACE VIEWpublic.schools_district_map
ASSELECTsch.schnum,sch.oid,sch.abbreviation,sch.school_level,sch.geom,l.label_x,l.label_y
FROMtemp_schools_label sch LEFTJOINdistrict_map_labels l
ONsch.schnum =l.schnum;|
And here are the rules I've applied to make the view 'editable':
|--delete rulecreateorreplace
rule"delete_label"asondeletetoschools_district_map do instead
deletefromschools_district_map whereoid =old.oid;--insert
rulecreateorreplace
rule"insert_label"asoninserttoschools_district_map do instead
insertintoschools_district_map
(label_x,label_y)values(new.label_x,new.label_y);--update
rulecreateorreplace
rule"labels_update"asonUPDATETOschools_district_map do instead
updateschools_district_map setlabel_x =new.label_x ,label_y
=new.label_y whereoid =new.oid;|
QGIS is then set to display the labels using the label_x and
label_y field.
I used this post as a guide to build the view, rules:
http://gis.stackexchange.com/questions/88120/how-to-set-posgis-default-sequential-value-in-a-qgis-editable-view
<http://gis.stackexchange.com/questions/88120/how-to-set-posgis-default-sequential-value-in-a-qgis-editable-view>
If anyone can spot where I might have left something out, or if
there is a glaring oversight on my part, OR if this is maybe a bad
idea... let me know!
Thank you!!!
-Matt Baker
Denver Public Schools
Denver, CO
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