Re^6: MongoDB replacing an array

[neilwatson]

There is not much more to show. Most is boring data manipulation that leads to the final array. The array holds only numbers. Nothing embedded.

my $conn = MongoDB::Connection->new;
my $db = $conn->mydb || die "$!";
my ($col, $cols, @cols, $q, $doc, @b, @c, @new, $x, $date, $l, $host);
+ 

@cols = $db->collection_names;

foreach $cols (@cols) {

Above a loop through some collections and for each make the new array. Then I try to replace the array.

if ( @new > 1 ){

        foreach my $xxx (@new){ print '@new = '.strftime('%Y-%m-%d', l
+ocaltime($xxx))."\n"; }
      $col->update( 
                 { "host" => $host },
                 {
                            '$set' => {  "timestamp" => @new }
                 },
                 { 'multiple' => 1, 'safe' => 1 }
      ) || die "$!";

The foreach loop above is just to show there is data in @new. That works :). The update fails. The documentation for MongoDB is a bit sparse. I assume my syntax is wrong. Alas, I cannot figure how.

[Mr. Muskrat]

I'm hoping that I can learn a bit about MongoDB from trying to help you. Is the update happening within the @cols foreach loop? How are you getting $col? $col = $db->$cols;?

Based on your @new foreach print, it looks like you are storing multiple timestamps in each record. Is that what you intended? If so, it seems odd to me to store timestamps in a column named timestamp. :)

[neilwatson]

Yes, I am getting $col as you describe. No issue there. Yes, multiple timestamps in a record. This is what I intend.

[Mr. Muskrat]

Perhaps my short example script that seems to be working will help shed some light on what's wrong with yours? At the very least, I've gotten a little exposure to MongoDB out of this experience.

#!/bin/env perl
use strict;
use warnings;
use Data::Dumper;
use MongoDB;
use Try::Tiny;

my $conn;
# the connection can fail
try {
    $conn = MongoDB::Connection->new;
}
catch {
    chomp( my $err = $_ );
    $err =~ s/ at .*//;
    die "Unable to connect to the default MongoDB ($err)";
};

my $db = $conn->mydb; # shouldn't ever die because MongoDB will create
+ it if it doesn't exist
my $hosts = $db->hosts; # ditto

$hosts->insert({host => "127.0.0.1", timestamp => [ qw( 20110101 20110
[phone] ) ]});
$hosts->insert({host => "127.0.0.2", timestamp => [ qw( 20110101 20110
[phone] ) ]});
$hosts->insert({host => "127.0.0.3", timestamp => [ qw( 20110707 20110
[phone] ) ]});
$hosts->insert({host => "127.0.0.1", timestamp => [ qw( 20111010 20111
[phone] ) ]});
$hosts->insert({host => "127.0.0.2", timestamp => [ qw( 20110404 20110
[phone] ) ]});

my $all_hosts = $hosts->find;

my $ts;
while ( my $host = $all_hosts->next )
{
    push @{$ts->{$host->{host}}}, @{$host->{timestamp}};
}

# add non-existant host just to try and get an exception
$ts->{'127.0.0.4'} = [ qw( 20120606 ) ];

$all_hosts->reset;

for my $host ( keys %$ts )
{
    print "Updating $host...";

    my @new = @{ $ts->{$host} };

    # I wasn't able to get it to die even when trying to update a non-
+existant record
    # $rc->{updatedExisting} will contain a true/false value but $rc->
+{err} is always undef
    # but I feel better trying to catch the croak

    my $rc;
    try {
        $rc = $hosts->update(
            { host => $host },
            { '$set' => { timestamp => [ @new ] } },
            { multiple => 1, safe => 1 }
        );
    }
    catch {
        warn sprintf( "Couldn't update records for host %s, %s", $host
+, $_ );
    };

    print $rc->{updatedExisting} ? 'success' : 'failure', "\n";
}

while ( my $host = $all_hosts->next )
{
    printf "%s => %s\n", $host->{host}, Dumper( $host->{timestamp} );
}

$hosts->drop;
$db->drop;