[mapguide-users] working with selections ...

[Andy Morsell]

Hi Paul,
Are you refreshing the map somehow?  You will not see the selection until
this occurs via an API call back to the server.  In some almost identical
code of mine, I use a JavaScript function to call SetSelectionXML in the
mapFrame.  Or, a call to ZoomToView in the mapFrame also works since it has
to redraw the map and will include the new selection object.

I hope this helps. 


Andy Morsell, P.E.
Spatial Integrators, Inc.
http://www.SpatialGIS.com

-----Original Message-----
From: Paul Spencer [mailto:pspencer at dmsolutions.ca] 
Sent: Monday, August 14, 2006 2:46 PM
To: users at mapguide.osgeo.org
Subject: [mapguide-users] working with selections ...

All,

I've been pulling what little hair I have left out of my head over this!

I would like to create a selection in the map using the PHP API.

I have the following code:

$map = new MgMap();
$map->Open($resourceService, $mapName);
$layerObj = $map->GetLayers()->GetItem($layerName);
$featureResId = new MgResourceIdentifier($layerObj->GetFeatureSourceId
());
$featureGeometryName = $layerObj->GetFeatureGeometryName();
$class = $layerObj->GetFeatureClassName(); $queryOptions = new
MgFeatureQueryOptions(); $queryOptions->SetFilter($filter);
$wktRW = new MgWktReaderWriter();
$geom = $wktRW->Read($spatialFilter);
$queryOptions->SetSpatialFilter($featureGeometryName, $geom,
MgFeatureSpatialOperations::Inside);
$featureReader = $featureService->SelectFeatures($featureResId,
$class, $queryOptions);
$selection = new MgSelection($map);
$selection->AddFeatures($layerObj, $featureReader, 0);
$selection->Save($resourceService, $mapName);

If I add this ...

echo countFeatures($featureReader);
function countFeatures($featureReader) {
     $i = 0;
     while ($featureReader->ReadNext()) {
         $i++;
     }

     return $i;
}

it tells me that I have the appropriate number of features in the feature
reader (for the geom and attribute filter chosen) ... in my test cases, it
was over 7000 features so I limited it spatially to about 200 ... but I
don't leave this in because it consumes the features and nothing gets added
to the selection :)

The problem is that after the selection is saved, I don't get anything
highlighted on the map.  I have another PHP script that retrieves the
properties of selected features.  It works if I use the mapagent to select
the features but it doesn't work if I use this php script ... well, it
reports that there is one layer with a selection but no features on it.

The problem occurs if I use just a basic filter, just a spatial filter, or
both combined.  It also occurs regardless of the number of features selected
from 1 to the full 7000+.

I also tried using my second php script inline to read the selection info
and no joy.  The script that reads the selection info looks like:

$layers = $selection->GetLayers();
$layer = $layers->GetItem(0); //yes there is one layer in the result
$layerClassName = $layer->GetFeatureClassName(); $selectionString =
$selection->GenerateFilter($layer, $layerClassName); $layerFeatureId =
$layer->GetFeatureSourceId(); $layerFeatureResource = new
MgResourceIdentifier($layerFeatureId);
$queryOptions->SetFilter($selectionString);
$featureReader = $featureService->SelectFeatures ($layerFeatureResource,
$layerClassName, $queryOptions); //... etc etc etc

The feature class name is the same in both cases.  The filter seems
appropriate.

I am obviously missing something here but I cannot see what it is.  I did
try saving the $map as well, with no obvious change.  Or is it a bug?  Oh, I
also tried saving the selection as XML and creating a new selection and
initializing it from the XML but that didn't seem to change anything either.

Cheers

Paul

+-----------------------------------------------------------------+
|Paul Spencer                           pspencer at dmsolutions.ca   |
+-----------------------------------------------------------------+
|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/|
+-----------------------------------------------------------------+





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