[mapguide-trac] #1782: Customized function such as "EXTENT" can't be run on SQL Server Spatial

[MapGuide Open Source]

#1782: Customized function such as "EXTENT" can't be run on SQL Server Spatial
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   Reporter:  sparkliu         |       Owner:     
       Type:  defect           |      Status:  new
   Priority:  low              |   Milestone:     
  Component:  Feature Service  |     Version:     
   Severity:  trivial          |    Keywords:     
External_id:                   |  
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 When coming to customized function such as "EXTENT", MapGuide server will
 try to calculate by itself instead of using FDO provider. So it will
 request the actual property instead of the expression into FDO. When
 getting properties from reader, it first check if the return column number
 is only 1, and use the first column as return column.

 However, there is no guarantee in FDO interface that the return reader
 only contains the requesting column. For example, SQL Server spatial adds
 PK column as well, and many code may have been written depending on that.

 So to make the code robust, if there are more than one columns returned,
 we should parse the expression when we gets the reader and only use the
 column we need.

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Ticket URL: <http://trac.osgeo.org/mapguide/ticket/1782>
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