[mapserver-users] default values if not provided in the URL

[Puneet Kishor]

David,

On Oct 27, 2011, at 11:19 AM, Fawcett, David (MPCA) wrote:

> Two hackish thoughts:
> 
> 1.  Utilize a pair of mapfiles.  The first one has all of the classes on by default.  The second one has all of the class with STATUS OFF.  
> 
> On the client side, you determine if you have any class args and route the request to the appropriate mapfile. If the client has a request with class args, you append one of these for each class  '&map.layer[0].class[3]=status on' (specifying the correct layer and class index values)
> 


The mapserver request is being made in a number of ways. If there is control on the client side, then, yes, different map files can be requested.

	http://server/mapall returns all the classes, and
	http://server/mapfew?class=Foo,Bar returns only Foo and Bar

However, the same URI is to be reused in other client apps as well (such as OL), so the ability to choose which map file to request is limited. In any case, for a number of "external" reasons, the URI is supposed to be unique, so http://server/mapall and http://server/mapfew violate that principle, however, http://server/mapthem (defaulting to 'class=All') and http://server/mapthem?class=Foo,Bar do not violate that uniqueness principle.

Alright, moving on ...

> If you only had a few classes, you could easily manage this with one mapfile (without running up against the character limits on GET requests)
> 

I said earlier that I have 100s of classes. I was wrong. Turns out I have 49 classes in this map file. However, in another map file I do have almost 700 classes. The use case is either the user gets all, or is able to specify one or two to filter and show only those.


> 2.  What are you really trying to do?  It seem like classes are for selecting and symbolizing/formatting data for output.  Do you really want to filter out the data using a filter at the layer level.  If you can avoid running all of your data through the expressions for each class, it should perform better too.
> 


Dunno how else to explain but with the following text -- the table (aka a layer) has a column called "classes" and these classes map to specific colors stored in another column.

I want to be able to return a map as per the URI rules above.


> David.
> 
> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Puneet Kishor
> Sent: Thursday, October 27, 2011 10:50 AM
> To: mapserver-users at lists.osgeo.org
> Subject: [mapserver-users] default values if not provided in the URL
> 
> the fine manual says http://mapserver.org/cgi/runsub.html
> 
>> Since version 5.6, you can provide a default value for any substitution 
>> parameter, that will be applied if the parameter was not found in the url. 
>> You do this by providing special entries inside the layer metadata :
>> 
>> 	METADATA
>> 		'default_sound' 'yes'
>> 		'default_nseats' '5'
>> 		'default_multimedia' 'yes'
>> 	END
>> 
>> In this example, the mapfile will be created as if the url contained 
>> "&sound=yes&nseats=5&multimedia=yes"
> 
> 
> Right then. Except, I want *all* my classes to be drawn if no class has been provided. And, if one or more classes have been provided, then I want only those to be drawn. So, 
> 
> 	http://server/mapfile?mode=map
> 
> should return a map with all the 100+ classes in a layer. And 
> 
> 	http://server/mapfile?mode=map&classes=Foo,Bar
> 
> (or some other variation of the above) should return a map with only the requested classes in the layer. I can't think of anyway of doing the above without resorting to scripting, and I still have had no luck with WMS returned from Perl MapScripting.
> 
> Suggestions.
> 
> --
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>