[asterisk-users] AEL: how to check if variable is defined

[Philipp Kempgen]

Philipp Kempgen schrieb:
> Klaus Darilion schrieb:
>> I use an "if" condition in extensions.ael to check if a channel variable 
>> is defined and if defined I add a certain header:
>> 
>> context toNormaleRufe {
>>    _X. => {
>>             if (${NUMBER}) {
>>                 SIPAddHeader(X-NUMBER: ${NUMBER});
>>             };
>>             ...
>>    };
>> 
>> This works fine, except NUMBER starts with the + sign.
>> 
>> I tried using quotes but
>>     if ("${NUMBER}")
>> evaluates always true.
>> 
>> What is the suggested way to solve this?
> 
> if ("${NUMBER}" != "") {
>     // ...
> }
> 
> That doesn't tell you whether the variable is defined but in
> most cases (if any) that doesn't matter anyway.

But I guess it wouldn't hurt to add a DEFINED() function to
Asterisk.

if (DEFINED(myvariable)) {
    // ...
}


   Philipp Kempgen

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