[mapserver-users] Using a attribute substring for labeling

[Lime, Steve D (MNIT)]

Jeff's suggestion is a good one. There's no way to do that using text expressions - you can concatenate and do simple transformations (e.g. toupper) but there is no substring operator. Would be a nice addition... --Steve

-----Original Message-----
From: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Jeff McKenna
Sent: Monday, February 29, 2016 7:28 AM
To: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] Using a attribute substring for labeling

On 2016-02-29 9:02 AM, lars lingner wrote:
> Hello,
>
> while using a ShapeFile, created with gdaltindex, as data source for a
> layer I'd like to use a substring of the location attribute for labeling.
>
> I could (and probably will) preprocess the ShapeFile to add the label
> text as additional attribute. But I wanted to try this step within
> MapServer first.
>
> My current example contains a path and file name. The file name has a 4
> digit number in it I would like to use as label. To make it more
> complicated, the substring has various positions within the whole string.
> Maybe there is a way with tostring() which accepts sprintf formatting,
> but I couldn't figure out the correct syntax yet.
>
> With a database layer of course I would be able to use SQL to extract a
> substring and pass it as additional attribute, but not with a ShapeFile.
>
> Is there a way to extract a substring from an attribute value and use it
> as label? It would be nice to have a function available to use in
> EXPRESSION or TEXT parameter.
>
> Thank you in advance for any hints.
>
> Lars

Hi Lars,

Did you try piping this shapefile layer through an OGR connection 
(CONNECTIONTYPE OGR) and then passing your SQL in the data statement? 
I'd first start at the ogrinfo commandline, and test your SQL there with 
the -sql switch, and then move to the mapfile next.

Otherwise I'd probably need a sample of your data to dive into this.

-jeff






-- 
Jeff McKenna
MapServer Consulting and Training Services
http://www.gatewaygeomatics.com/




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