Accessing Compressed Blobs from outside NAV (NAV2013)

21.01.14 – This Solution was not completly working, here is the new solutions, tested on NAV2013 R2 : https://devch.wordpress.com/2014/01/21/accessing-compressed-blobs-from-outside-nav-nav2013-revisited/

 

Just a short hint for anyone interested in accessing BLOB Fields in NAV. In the new Version, the BLOB compression is now longer a proprietary format, NAV now uses the .net deflate Class to compress the binary objects. (In a previous blogpost (https://devch.wordpress.com/2012/01/12/read-content-of-nav-notesblobs-from-sql/) I stated the need for disabling the compression on BLOB fields to access them from outside NAV)

Therefore you can no easily use the DeflateStream Class to decompress the content and access it.

So to decompress the content, the method would look something like this:

    public static long Decompress(Stream inp, Stream outp)
    {
    	byte[]  buf = new byte[BUF_SIZE];
    	long    nBytes = 0;

    	// Decompress the contents of the input file
    	using (inp = new DeflateStream(inp, CompressionMode.Decompress))
    	{
    		int len;
    		while ((len = inp.Read(buf, 0, buf.Length)) > 0)
    		{
    			// Write the data block to the decompressed output stream
    			outp.Write(buf, 0, len);
    			nBytes += len;
    		}
    	}
    	// Done
    	return nBytes;
    }