[fdo-internals] Zero-length Data Properties

[Jackie C. Ng]

Thomas,

But for something like SDF, even it returns -1 for string/BLOB/CLOB. It is a
fixed format with fixed specifications. What is the deal there?

- Jackie


Thomas Knoell wrote:
> 
> Hi Jackie,
> 
> The -1 is an indicator that the exact value cannot be determined. This is
> especially the case in ODBC that can connect to multiple data store
> sources, all with different limitations. Because the capability
> information is available before a connection is actually established more
> precise information cannot be provided.
> 
> Thanks
> 
>   Thomas
> 
> -----Original Message-----
> From: fdo-internals-bounces at lists.osgeo.org
> [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Jackie C. Ng
> Sent: Tuesday, September 02, 2008 4:47 AM
> To: fdo-internals at lists.osgeo.org
> Subject: [fdo-internals] Zero-length Data Properties
> 
> 
> Hi All,
> 
> I have two related questions about Data Properties
> 
> A) Why does FDO allow zero-length string/CLOB/BLOB data properties? In my
> feeble little mind, zero-length strings/CLOBs/BLOBs makes no sense
> whatsoever.
> 
> B) I noticed that for some providers, the GetMaximumDataValueLength()
> method
> returns -1 for string/BLOB/CLOB properties. The same goes for
> GetMaximumDecimalPrecision() and GetMaximumPrecisionScale(). If I were to
> do
> something like this:
> 
> ISchemaCapabilities capabilities;
> ...
> DataPropertyDefinition def = new DataPropertyDefinition("StringProp", "");
> def.Length =
> capabilities.GetMaximumDataValueLength(DataType.DataType_String);
> 
> It would throw an exception because the Length property of
> DataPropertyDefinition can't be negative. So what should this value (-1)
> be
> interpreted as?
> 
> - Jackie
> 
> -----
> http://themapguyde.blogspot.com
> 
> http://www.linkedin.com/in/jackieng
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-----
http://themapguyde.blogspot.com

http://www.linkedin.com/in/jackieng
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