Help needed with uniqueidentifier

[scohen28]

I'm retrieving the ID from a sql server database as follows:

import ("github.com/nu7hatch/gouuid")
var theID []byte
err := db.QueryRow("select id from table where item='xxx').Scan(&theID)
fmt.Println(theID)
idStr, _ := uuid.Parse(theID)
fmt.Println(idStr)

Prints:
[249 214 3 106 70 136 42 75 185 33 204 184 168 141 203 14]
f9d6036a-4688-2a4b-b921-ccb8a88dcb0e

When I directly query the table using Sql Management Studio, for the same query I get:
6A03D6F9-8846-4B2A-B921-CCB8A88DCB0E

I also tried the following, but it returns the same 'f9d...' value
b := theID
b[6] = (b[6] & 0x0F) | 0x40
b[8] = (b[8] &^ 0x40) | 0x80
theIDStr := fmt.Sprintf("%x-%x-%x-%x-%x", b[:4], b[4:6], b[6:8], b[8:10]

What is the correct parsing function to use on the returned []byte to resolve to the same value that Sql Server is presenting?

[denisenkom]

First four parts of guid are integers 32 16 16 16 bit respectively, looks like Parse function incorrectly interprets data big-endian/little-endian (http://en.wikipedia.org/wiki/Endianness) mixup. You can swap order of bytes to get correct byte order for your function or maybe Parse function can take parameters specifying endianness of the input.

[scohen28]

Thanks - I was playing around with this and had come up with:
b := orgID
b[0], b[1], b[2], b[3] = b[3], b[2], b[1], b[0]
b[4], b[5] = b[5], b[4]
b[6], b[7] = b[7], b[6]

and that resolved it.

My setup is running a GO program on a Mac and retrieving (obviously) from a Windows Machine. If the program was to be cross-compiled onto PC, Mac, Linux (I don't have a PC to test on) - would I need to test for the OS and if PC not do the byte swapping?

[sachin-walia]

Thanks @scohen28 this was really helpful.

[shueybubbles]

@kardianos one problem with requiring an app to scan to *mssql.UniqueIdentifier instead of *interface{} is the scanner doesn't currently support a null uniqueidentifier.
select convert(uniqueidentifier, null) will fail
sql: Scan error on column index 0, name "": mssql: cannot convert <nil> to UniqueIdentifier