How to loop json results in Perl - perl

Question

I am trying to output JSON from a perl script that accesses a mysql database.
How I can I loop through my query returns and turn that into JSON using the JSON module?
When I do this all I get is 1 return
while($query_handle->fetch()) {
$jsonStructure->{event};
$jsonStructure->{event}->{evid} = $evid;
$jsonStructure->{event}->{component} = $component;
$jsonStructure->{event}->{firstTime} = $firstTime;
$jsonStructure->{event}->{lastTime} = $lastTime;
$jsonStructure->{event}->{count} = $count;
$jsonStructure->{event}->{summary} = $summary;
$jsonStructure->{event}->{severity} = $severity;
}
Basically I have many events and don't know how to say event[0]...
Thank You

Answer 1

I think what you're looking for is this:
push #{ $jsonStructure->{events} }, {
evid => $evid,
component => $component,
...,
};
although even that is probably overkill, because you can probably do something like:
while (my $row = $dbh->fetchrow_hashref) {
push #{ $jsonStructure->{events} }, $row;
}
if all of the column names in the DB are the same as the field names you want in the JSON, and you want all columns, or:
my #keys = qw(evid component firstTime ...);
while (my $row = $dbh->fetchrow_hashref) {
my %hash;
#hash{#keys} = #$row{#keys};
push #{ $jsonStructure->{events} }, \%hash;
}
if you only want some columns, or:
# DB colname => JSON field name
my %mapping = (
event_id => 'evid',
component => 'component',
first_time => 'firstTime',
...,
);
while (my $row = $dbh->fetchrow_hashref) {
my %hash;
#hash{ values %mapping } = #$row{ keys %mapping };
push #{ $jsonStructure->{events} }, \%hash;
}
for a completely arbitrary mapping. Power of Perl and all that. :)