Handle UUID mongo query in golang

In order to query mongodb with csharp guid in golang, you would need the following conversions:

func CsuuidToBinary(key string) []byte {
    hexStr := strings.Replace(key, "-", "", -1)
    first := hexStr[6:8] + hexStr[4:6] + hexStr[2:4] + hexStr[0:2]
    second := hexStr[10:12] + hexStr[8:10]
    third := hexStr[14:16] + hexStr[12:14]
    fourth := hexStr[16:len(hexStr)]
    hexStr = first + second + third + fourth

    data, _ := hex.DecodeString(hexStr)
    return data
}

and to use it with MongoDB Go Driver

binaryKey := CsuuidToBinary("246076cf-b5cf-4d5a-9f15-1d46aa2108a1")

clientOptions := options.Client().ApplyURI("your_mongo_connection_string")
conn.Collection("Test").FindOne(context.Background(), bson.M{"Key": primitive.Binary{Subtype: 0x03, Data: binaryKey}})

and to convert back to GUID from binary:

func BinaryToCSUUID(data []byte) string {
	const byteSize = 16
	if len(data) != byteSize {
		return
	}
	var u [byteSize]byte
	copy(u[:], data)

	buf := make([]byte, 36)

	hex.Encode(buf[0:2], u[3:4])
	hex.Encode(buf[2:4], u[2:3])
	hex.Encode(buf[4:6], u[1:2])
	hex.Encode(buf[6:8], u[0:1])
	buf[8] = '-'
	hex.Encode(buf[9:11], u[5:6])
	hex.Encode(buf[11:13], u[4:5])
	buf[13] = '-'
	hex.Encode(buf[14:16], u[7:8])
	hex.Encode(buf[16:18], u[6:7])
	buf[18] = '-'
	hex.Encode(buf[19:23], u[8:10])
	buf[23] = '-'
	hex.Encode(buf[24:], u[10:])
	return string(buf)
}