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non existent array item
Posted: 04 Jan 2018 10:24
by newturn
Hi there,
if i use
Code: Select all
notification_tag = antag[0]; // is not existent
i get the error: Value null is not a list or map.
That's fine. But there is no shorthand to test for an value. I always get an exception!!! And if you have many of those variables it's an unnecessary mess.
Do i have always to write something like this:
Code: Select all
if(isList(antag) and length(antag) >= 0)
{
notification_tag = antag[0];
}
else
{
notification_tag = "";
}
I would like to use something like:
Code: Select all
notification_tag = convertNull(antag[0], "");
or
Code: Select all
notification_tag = convertNull(!isList(antag[0]), "");
or better
just give a null or "" back
is this possible?
best regards
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Re: non existent array item
Posted: 04 Jan 2018 12:00
by Desmanto
Automagic need a new function similar to excel, called
isError(value) and
ifError(value, value_if_error).
So far, there is no way to deal with the error/exception, except you catch it outside of the script, by changing the connector from normal to exception.
That will split your script into to parts, which is not convenient.
Meanwhile, you can set up your script like this
Code: Select all
if(length(antag)>0)
notification_tag = antag[0];
notification_tag = convertNull(notification_tag, "");
Still not a perfect solution, but at least it doesn't need the branch else, which usually will takes up several lines for a tidy coding.
if we can have new function as ifError(), maybe it will be possible to use something like.
Code: Select all
notification_tag = ifError(antag[0], "");
Re: non existent array item
Posted: 10 Jan 2018 00:51
by newturn
Thank you very much. This is a nice way until we get an iferror function or something like that! I tried many ways but always got the is "null or not a list" error. I will try this also with empty maps.
Re: non existent array item
Posted: 10 Apr 2018 17:21
by Desmanto
Bumping old thread. I am indexing the thread, and reread this. I've found a better method to do it using inline expression. No need for isError() anymore.
This is the longer version of the script
Code: Select all
if(length(antag)>0)
{
notification_tag = antag[0];
}
else
{
notification_tag = "";
}
You can move the notification_tag to the front and assign the value immediately, putting it in single line
Code: Select all
notification_tag = if(length(antag)>0) antag[0] else "";
Ah, the single line code version is really satisfying.
