Page 309 - Asterisk™: The Future of Telephony

If the pin entered matches, we validate the login with the valid_login extension. First
we utilize the CHANNEL variable to figure out which phone device we’re calling from. The
CHANNEL variable is usually populated with something such as: SIP/desk_1-ab4034c, so
we make use of the CUT() function to first pull off the SIP/ portion of the string and
assign that to LOCATION. We then strip off the -ab4034c part of the string, discard it, and
assign the remainder of desk_1 to the LOCATION variable.

exten => valid_login,1,NoOp()
; CUT off the channel technology and assign to the LOCATION variable
exten => valid_login,n,Set(LOCATION=${CUT(CHANNEL,/,2)})
; CUT off the unique identifier and save the remainder to the LOCATION variable
exten => valid_login,n,Set(LOCATION=${CUT(LOCATION,-,1)})
We utilize yet another custom function, HOTDESK_CHECK_PHONE_LOGINS(), created in
func_odbc.conf to check if any other users were previously logged in to this phone and
had forgotten to log out. If the number of previously logged in users was greater than
0 (and should only ever be 1, but we check for more anyway and reset those, too), it
runs the logic in the logout_login extension.
If no previous agents were logged in, we update the login status for this user with the
HOTDESK_STATUS() function:

exten => valid_login,n,Set(ARRAY(USERS_LOGGED_IN)=${HOTDESK_CHECK_PHONE_
LOGINS(${LOCATION})})
exten => valid_login,n,GotoIf($[${USERS_LOGGED_IN} > 0]?logout_login,1)
exten => valid_login,n(set_login_status),NoOp()

; Set the status for the phone to '1' and where we're logged into
; NOTE: we need to escape the comma here because the Set() application has arguments
exten => valid_login,n,Set(HOTDESK_STATUS(${E})=1\,${LOCATION})
exten => valid_login,n,GotoIf($[${ODBCROWS} < 1]?error,1)
exten => valid_login,n,Playback(agent-loginok)
exten => valid_login,n,Hangup()
We create a write function in func_odbc.conf like so:
[STATUS]
prefix=HOTDESK
dsn=asterisk
write=UPDATE ast_hotdesk SET status = '${VAL1}', location = '${VAL2}' WHERE extension
= '${ARG1}'
The syntax is very similar to the read syntax discussed earlier in the chapter, but there
are a few new things here, so let’s discuss them before moving on.
The first thing you may have noticed is that we now have both ${VALx} and ${ARGx}
variables in our SQL statement. These contain the values we pass to the function from
the dialplan. In this case, we have two VAL variables, and a single ARG variable that were
set from the dialplan via this statement:
Set(HOTDESK_STATUS(${E})=1\,${LOCATION})

Getting Funky with func_odbc: Hot-Desking | 281