add to JSON ($payload={}) on condition - json

Question

I feed JSON to some webhook to trigger a notification (M$ Teams). This works well. However, I want to extend my Perl script: I need to add a new node to my "messagecard" construct on a certain condition.
E.g. I defined this:
my $payload={};
$payload = {
'#type' => 'MessageCard',
'#context' => 'http://schema.org/extensions',
themeColor => $event{COLOR},
text => $event{SERVICEOUTPUT},
sections => [{
facts => [{
name => 'Type',
value => "$event{NOTIFICATIONTYPE} $event{ADDITIONALINFO}"
},
]
}],
potentialAction => [{
'#type' => "OpenUri",
name => "View Monitoring",
targets => [{
os => "default",
uri => $naemon_url
}]
}]
};
$ua = LWP::UserAgent->new;
my $req = POST($opt_webhook
, 'Content-Type' => 'application/json; charset=UTF-8'
, 'Content' => encode_json($payload)
);
my $resp = $ua->request($req);
And if (conditon), I want to extend this as follows (order is important):
$payload = {
'#type' => 'MessageCard',
'#context' => 'http://schema.org/extensions',
themeColor => $event{COLOR},
text => $event{SERVICEOUTPUT},
sections => [{
facts => [{
name => 'Type',
value => "$event{NOTIFICATIONTYPE} $event{ADDITIONALINFO}"
},
]
}],
potentialAction => [{
'#type' => "OpenUri",
name => "View Monitoring",
targets => [{
os => "default",
uri => $naemon_url
}]
},
{
'#type' => "OpenUri",
name => "Notes (Logs, Docs,..)",
targets => [{
os => "default",
uri => $event{SERVICENOTESURL}
}]
}]
};
I am unsure how this can be achieved. Can anyone please provide wisdom how to tackle this?

Answer 1

You can push into the array reference that you've got inside your potentialAction key. In order to do that, you need to dereference it as an array.
my $payload = {
'#type' => 'MessageCard',
potentialAction => [{
name => "View Monitoring",
targets => [{
os => "default",
}]
}]
};
if ($maybe) {
push #{ $payload->{potentialAction} }, {
name => "Notes (Logs, Docs,..)",
targets => [{
os => "default",
}]
};
}
If your Perl version is 5.24 or newer you can also use postfix dereferencing, which some people find easier to read.
push $payload->{potentialAction}->#*, ...
See perlref and perlreftut for more information.