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<div class="moz-cite-prefix">On 2014/11/07 19:19, Zoltan Szecsei
wrote:<br>
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<blockquote cite="mid:545CFF17.2080103@geograph.co.za" type="cite">
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<div class="moz-cite-prefix">Thanks for the pointer to 'Save Layer
Definition file' - I've never noticed that, so I'll play with
that for a bit.<br>
<br>
<br>
On 2014/11/07 18:59, Andreas Neumann wrote:<br>
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<blockquote cite="mid:545CFA6B.3040907@carto.net" type="cite">
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<br>
However, if you save a layer definition file along with the
shapefile and re-add that, they are preserved. So you can just
store the layer definition file along with the shape and you are
fine to share the data with your colleagues, preserving virtual
fields ;-)<br>
</blockquote>
</blockquote>
Hi,<br>
OK - not very intuitive, (to have to either drag and drop the qlr
file into the layer panel, or to "add layer from definition file")<br>
<br>
Any reason that QGIS can't be made to look for qlr files when
opening the SHP file "the normal way"?<br>
<br>
Regards & thanks for the help.<br>
Zoltan<br>
<br>
<blockquote cite="mid:545CFF17.2080103@geograph.co.za" type="cite">
<blockquote cite="mid:545CFA6B.3040907@carto.net" type="cite"> <br>
Andreas<br>
<br>
<div class="moz-cite-prefix">On 07.11.2014 17:32, Zoltan Szecsei
wrote:<br>
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<blockquote cite="mid:545CF41A.1040704@geograph.co.za"
type="cite">
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<div class="moz-cite-prefix">Hi Andreas,<br>
I'll fiddle with the Postgis idea - thanks.<br>
The orange part below:<br>
I closed the shapefile, deleted from legend and re-opened it
- but could not see my virtual field, nor the expression I
used to create it.<br>
Have I missed a trick somewhere?<br>
<br>
Regards,<br>
Z<br>
<br>
On 2014/11/07 18:25, Andreas Neumann wrote:<br>
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<blockquote cite="mid:545CF265.1040604@carto.net" type="cite">
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Hi,<br>
<br>
What you probably ask for are database triggers combined
with storage. This is not what virtual fields are for. If
they were stored - they wouldn't be called virtual ;-)<br>
<br>
You can do that f.e. with Postgis. With shapefiles not. <font
color="#ff6600">However, if you share the project with the
other PC, the virtual fields work fine</font>.<br>
<br>
Andreas<br>
<br>
<div class="moz-cite-prefix">On 07.11.2014 17:21, Zoltan
Szecsei wrote:<br>
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<blockquote cite="mid:545CF16F.20604@geograph.co.za"
type="cite">
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<div class="moz-cite-prefix">Hi Matthias,<br>
Thanks for the quick answer.<br>
The virtual field acts just like I want it to, except
that it does not permanently store the column in the
attribute table.<br>
I tried getting clever by then adding a second 'Field
Calculation' to update the existing 'Sheet' field from
the virtual field, but that won't do it either.<br>
<br>
So, for me there are two shortcomings:<br>
<ol>
<li>To be able to store and recall the 'Expression'
and not lose it after closing the Field Calculator</li>
<li>To be able to add the virtual fields that you
create, into the attribute table.</li>
<li>(And then of course to re-open the Shape file on
another PC and have these Field Calculations still
functional)<br>
</li>
</ol>
Any further possibilities I can try?<br>
<br>
Regards & thanks again,<br>
Zoltan<br>
<br>
<br>
On 2014/11/07 18:01, Matthias Kuhn wrote:<br>
</div>
<blockquote cite="mid:545CECD7.9030808@gmx.ch" type="cite">
<pre wrap="">Hi Zoltan,
Since QGIS 2.6 this possibility exists. It is called "Virtual Field".
You must not create the attribute when creating the shapefile. Just open
the field calculator, create a new field in there and check the "virtual
field" checkbox.
Regards,
Matthias
On 07.11.2014 16:54, Zoltan Szecsei wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
I'm using QGIS 2.6.0 on Win 7 x64 - installed via OSGEO4w
Is there a way to store your field calculator expression to always
process and update that specific field, should geometry be edited or
created for that Layer?
Let's say I want to create a blank POINT shape file, with a text
attribute called "Sheet".
Whenever a POINT is created or moved, I want this field to be
dynamically updated with:
tostring(abs(toint($y)))+tostring(abs(toint($x)))
For testing thus far have:
* created 2 points
* Opened the field calculator, clicked 'Update Existing Field' and
put in the expression.
* The two existing points now have the correct TEXT values in the
Sheet field
* I close the Field calculator
* Create a new point in my layer
* open the attribute table to find that the 'Sheet' field for this
new point is blank
* I open the Field Calculator and I cannot even find a way to call
back the previous expression I used.
Am I using the correct QGIS functionality to achieve what I need to,
and if so, where am I going wrong?
Thanks & regards,
Zoltan
--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
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===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
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===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
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===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
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<pre class="moz-signature" cols="72">--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
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