[mapguide-users] mgnullreferenceexception after MgLayer::GetClassDefinition()

[Jackie Ng]

I theorize that $map and $layers might have been cleaned up after setLayer()
returned.

When you're calling GetClassDefinition() on the cached $this->layer, it
internally retrieves its parent map from its owner MgLayerCollection to
create the necessary MgFeatureService to fetch the class definition. But
because both the $map and $layers have been cleaned up, the parent map
reference is lost and that's probably where the MgNullReferenceException is
coming from:

http://trac.osgeo.org/mapguide/browser/branches/2.6/MgDev/Common/MapGuideCommon/MapLayer/Layer.cpp#L79

Of course this is just a theory, which you can test by promoting $map up to
a class member variable instead of a local variable in setLayer().

- Jackie



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