Reading a blob field from database using IDataRecord

Question

I need to populate a byte array from a database field using an IDataRecord and i needed help on how to get this done.

public class MyClass
{
   public string Name {get;set;}
   public byte[] ImageData { get; set;}
}

// Data Layer

public MyClass Populate(IDataRecord dr)
{
   var myClass = new MyClass();
   myClass.Name = myDataRecord.GetString(myDataRecord.GetOrdinal("NAME"));
   myClass.ImageData = // Need info on how to load this

}

Thanks for any help

score 10 · Accepted Answer · 2010-12-30 04:17:02Z

10

You can simply cast by using GetValue() method:

public MyClass Populate(IDataRecord dr)
{
   var myClass = new MyClass();

   int ordinal1 = myDataRecord.GetOrdinal("NAME");
   int ordinal2 = myDataRecord.GetOrdinal("IMAGEDATA");

   myClass.Name = myDataRecord.GetString(ordinal1);
   myClass.ImageData = (byte[])myDataRecord.GetValue(ordinal2);
}

EDIT: The GetOrdinal() is necessary for reading the ordinal of a field by name.

edited Dec 30, 2010 at 4:17

answered Dec 29, 2010 at 16:37

user432219

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Comments

jason · Accepted Answer · 2010-12-29 16:38:08Z

0

Is there some reason that you can't use IDataRecord.GetBytes as in

int imageDataOrdinal = myDataRecord.GetOrdinal("ImageData");
long bytesRead = myDataRecord.GetBytes(
                     imageDataOrdinal,
                     0,
                     myClass.ImageData,
                     0
                     length
                 );

answered Dec 29, 2010 at 16:38

jason

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2 Comments

Carl Onager Over a year ago

Please explain how to set the value of the length parameter

DarthGizka Over a year ago

@ Carl Onager: myDataRecord.GetBytes(imageDataOrdinal, 0, null, 0, 0). This is mentioned in the remarks section of the documentation page ('If you pass a buffer that is null, GetBytes returns the length of the row in bytes.'). The 'row' thing is misleading, of course. It should probably read 'blob' or something like that.

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