[mapserver-users] queryByRect throws an error

[Murty Maganti]

Hi Tamas

 

Yes, there is a workaround to prevent this issue. I am already taking
care in my code.

 

Thanks

Murty

From: Tamas Szekeres [mailto:szekerest at gmail.com] 
Sent: Wednesday, January 07, 2009 6:11 PM
To: Murty Maganti
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] queryByRect throws an error

 

Hi Murty,

Yes, you're correct. By setting the template parameter of these internal
layers like __embed__legend or __embed__scalebar causes the behaviour
you've reported before. However I'm not sure it should be denoted as a
bug since you could easily skip setting these parameters in your code.
Skipping these layers in the mapserver query code may cause slower
execution which is undesirable in most cases. I'm guessing there might
be some other occurrences where altering these special layers in
mapscript may also cause unexpected results.

Best regards,

Tamas




2009/1/7 Murty Maganti <MMaganti at oriongis.com>

Hi Tamas

 

Thanks for reply.

 

These are extracts from my code to replicate the issue

 

//Create map object

mapObj map = new mapObj("MyMap.map");

 

//draw map

map.draw() ; 

 

//Make sure some template name is defined. Otherwise, query will not be
successful.

            for (int i = 0; i < map.numlayers; i++)

            {

                if (string.IsNullOrEmpty(m_map.getLayer(i).template))

                {

                    m_map.getLayer(i).template = "abc";

                }

            }

 

//Perform the query now

map.queryByRect(map.extents);

 

 

I think after a call to map.draw(), a new layer '__embed__scalebar' is
added to layers collection. Setting template name to it is performing
the query on scalebar layer as well. 

 

I think the scalebar layer is not satisfying these two conditions in
msQueryByRect method of mapquery.c and hence getting used for query

 

    if(!msIsLayerQueryable(lp)) continue;

    if(lp->status == MS_OFF) continue;

 

 

Please let me know if you need more info or you need any test
application.

 

 

Thanks

Murty

 

From: Tamas Szekeres [mailto:szekerest at gmail.com] 
Sent: Tuesday, January 06, 2009 3:33 PM
To: Murty Maganti
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] queryByRect throws an error

 

Hi,

Could you provide a code/mapfile sample to reconstruct the issue? I've
never experienced such a problem, I've used this function many times
though.

Best regards,

Tamas



2009/1/6 Murty Maganti <MMaganti at oriongis.com>

mapObj.queryByRect(...)  (using C# map script) is throwing following
exception when there is an embedded scale bar on map.

 

Exception message: "msShapefileOpen(): Unable to access file. No (NULL)
filename provided.;msBuildPath: Unable to access file"

 

Removing the scale bar from map file works fine. 

 


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