[mapguide-users] Geting Selected Features

[Matt Feeney]

Trying to get the Features that have been selected from a Ajax Map Viewer.
The JavaScript is passing back the selection XML to the server side.

On the Page Postback, i read the Params that are returned, depending on the
correct parameter value i run the function below.

Private Sub ListSelected(ByVal sessionId As String, ByVal mapname As String,
ByVal selectionXML As String)

        Dim userInfo As MgUserInformation = New MgUserInformation(sessionId)
        Dim site As New MgSite()
        site.Open(userInfo)
        Dim siteConnection As New MgSiteConnection()
        siteConnection.Open(userInfo)
        Dim map As New MgMap()
        Dim mapId As MgResourceIdentifier = New
MgResourceIdentifier("Session:" + sessionId + "//" + mapname + "." +
MgResourceType.Map)
        Dim resourceService As MgResourceService =
siteConnection.CreateService(MgServiceType.ResourceService)
        map.Open(resourceService, mapname)
        Dim featureService As MgFeatureService =
siteConnection.CreateService(MgServiceType.FeatureService)


        Dim sel As MgSelection = New MgSelection(map, selectionXML)

        sel.Open(resourceService, mapname)

        Dim lyrs As MgReadOnlyLayerCollection = sel.GetLayers()

        For Each lyr As MgLayerBase In lyrs

            If lyr.Selectable = True Then

                Dim count As Integer = sel.GetSelectedFeaturesCount(lyr,
lyr.GetFeatureClassName())

                sel.GetSelectedFeatures(lyr, lyr.GetClassName(), False)

            End If

        Next

End Sub

The line of text in bold throws an exception which makes no sense. (see
Below)

OSGeo.MapGuide.MgNullReferenceException was unhandled by user code
  Message="Null reference."
  Source="MapGuideDotNetApi"
  StackTrace:
    - MgMap.GetService line 93 file
d:\buildforgeprojects\mapguide_open_source_v2.0\build_27.16\mgdev\common\mapguidecommon\MapLayer/Map.cpp 


Many Thanks in Advanace

Matt




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