[mapserver-users] Change CLASS Expression using MapScript

Mon Oct 12 16:56:52 PDT 2009

It makes sense but the class change needs to happen:

  1) by passing the change to the WMS server somehow (SLD?)
  2) by writing a custom mapfile that reflects the change
  3) by writing a custom WMS service that makes the change and then behaves as WMS

Others might have other/better ideas. I don't know enough about SLD to know if option 1 is
possible but that's the easiest. Basically you're configuring the WMS server on-the-fly
by passing SLD via OpenLayers. I know you can do that with straight MapServer CGI.

Steve

>>> On 10/12/2009 at 6:47 PM, in message
<1255391265612-3811491.post at n2.nabble.com>, Dash <jimlug at co.clackamas.or.us>
wrote:

> Thanks for the quick response.
> 
> I'll go ahead and make the appropriate change for the layerObj.  As for the
> change of expression with the mapfile, I did not know you had to save the
> changes.  I just wanted the expression to be changed based on what a user
> selects from a form.
> 
> The page that leads up to the map page allows a user to select either
> elementary, middle or high schools to display.  Since our GIS layer has
> these as attributes I wanted to refrain from specifying these layers
> multiple times in the mapfile.  I would rather pass an expression into the
> mapfile and display the appropriate level.  I hope this makes sense?  
> 
> I had this procedure working before, however, I was never specifiying WMS as
> a layer.
> 
> Thanks...
> 
> 
> Steve Lime wrote:
>> 
>> Couple of things:
>> 
>> 1) you don't need to open/close a layerObj to change it
>> 
>> 2) something doesn't make sense in your approach. Are you saving the
>> mapfile somehow with the
>> changes so that the subsequent WMS call can make use of it? I don't know
>> how the WMS call would
>> know you mucked with the class otherwise.
>> 
>> Steve
>> 
>>>>> On 10/12/2009 at 6:29 PM, in message
>> <1255390195922-3811433.post at n2.nabble.com>, Dash
>> <jimlug at co.clackamas.or.us>
>> wrote:
>> 
>>> Hey there folks,
>>> 
>>> I am banging my head against this problem for sometime now.  I have a
>>> MapFile that is set up to deliver WMS layers when requested through
>>> OpenLayers.  Within my web page I am trying to change the Class
>>> Expression
>>> (MapScript/PHP).  Below is the method I am using to gain access to the
>>> Class
>>> and change the expression.  I am performing this before I enter a body
>>> tag. 
>>> The body tag has a onload event that fires off the parameters/layers I am
>>> using within OpenLayers and makes the call to the WMS layers within my
>>> MapFile.  Am I missing something here?  I thought since I am declaring
>>> the
>>> expression before I'm displaying the map everything would be ok.  I've
>>> even
>>> retrieved the edited expression and it should work.  The only thing I can
>>> imagine is that it has something to do with a WMS setting.  Any help
>>> would
>>> be greatly appreciated.  Thanks.
>>> 
>>> <head>
>>> .
>>> .
>>> .
>>> </head>
>>> 
>>> <?php
>>> $situsEnc = $_POST['home'];
>>> $situs = urldecode($situsEnc);
>>> 
>>> $map_path="/something/other/than/dirty/socks/wms/";
>>> $map = ms_newMapObj($map_path."schools.map");
>>> 
>>> $mafLyr = $map->getLayerByName('maf');
>>> $mafLyr->open();
>>> $mafClass = $mafLyr->getClass(0);
>>> $mafClass->setExpression("('[situs]' = '" . $situs . "')");
>>> $mafLyr->close();
>>> 
>>> <body onload=i"nit()">
>>>   <div id="map"></div>
>>> </body>
>> 
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>> 
>> 