Page 529 - Asterisk™: The Future of Telephony

EVAL Evaluates stored variables
EVAL(variable)

EVAL() is one of the most powerful dialplan functions. It permits one to store variable
expressions in a location other than extensions.conf, such as a database, yet evaluate
them in the dialplan, as if they were included there all along. You can bet that EVAL()
is a cornerstone in making a dialplan truly dynamic.
; We might store something like "SIP/${DB(ext2chan/123)}" in the
; database entry for extension/123, which tells us to look up yet
; another database entry.
exten => _XXX,1,Set(dialline=${DB(extension/${EXTEN})})
exten => _XXX,n,Dial(${EVAL(${dialline})})
; Real world example (taken from production code)
exten => _1NXXNXXXXXX,n(generic),Set(provider=${DB(rt2provider/${route})}-nanp)
exten => _1NXXNXXXXXX,n(provider),Dial(${EVAL(${DB(provider/${provider})})})
exten => _1NXXNXXXXXX,n,Goto(nextroute)

See Also
Exec()

EXISTS Checks if value is non-blank
EXISTS(data)

Existence test: returns 1 if non-blank, 0 otherwise

FIELDQTY Counts fields
FIELDQTY(varname|delim)

Counts the fields, with an arbitrary delimiter

See Also
CUT()

FILTER Strips string of illegal characters

FILTER(allowed-chars|string)
Filters the string to include only the characters shown in allowed-chars:

; Ensure that the Caller*ID number contains only digits
exten => Set(CALLERID(num)=${FILTER(0123456789,${CALLERID(num)})})
This function may only be read, not set.

EVAL | 501