[Cartoweb-users] Creating a filter plugin

Dirk Jesko ml.dje at geocontent.de
Tue Apr 24 05:47:19 EDT 2007

Yes, we use persistent query results. I thought about it again and came 
to the conclusion that synchronizing query results can not work 
correctly in all cases. Since the boundary of the area queried is not 
saved, the result can not be extended if the new filter is less 
restrictive then the original one. Therefore, the best solution would be 
to remove all persistent query results (of the layer with the filter) if 
the filter changes. Question: How can the filter plugin remove the 
persistent results?

By the way, I was wondering, why I can set the DATA item of a layer 
object via the MapOverlay plugin, but not the FILTER. Wouldn't that be 
the better way to filter data? Or is it not possible to set the FILTER 
item via mapscript?


> do you use persistant query result?
>> Hello Oliver,
>> thanks. Everything is working now. After a few test, I found out that 
>> initializeRequest (not handlePreDrawing) needs to be used. Otherwise, 
>> the query plugin will not recognize the changed map object and return 
>> all results. Unfortunately, this causes another side effect: If a 
>> query result exists and the filter is changed, an error is triggered 
>> ("Attribute query returned no results") if none of the existing query 
>> results fits the new filter. If at least one result fits the filter, 
>> all are kept.
>> Do you have any idea, how I could synchronize the query results if 
>> the filter changes?
>> Regards,
>> Dirk

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