Insert MongoDB Server Date from Perl driver

The Perl MongoDB Driver uses DateTime objects to store Dates, and returns DateTime object back to you if you read dates from the database.

#!/usr/bin/env perluse strict;use warnings;use MongoDB;use MongoDB::OID;use DateTime;# database connection & collectionmy $conn  = MongoDB::Connection->new;my $db    = $conn->dates;my $log   = $db->log;# Delete Collection$log->drop;# Insert onemy $oid = $log->insert({ dt => DateTime->now });# Show allmy $all = $log->find;while ( my $entry = $all->next ) {    printf "_id: %s dt: %s\n", $entry->{_id}->to_string, $entry->{dt}->format_cldr("dd.MM.yyyy HH:mm:ss");}

If you execute it, it prints something like

_id: 50cb1b9321d30efd17000000 dt: 14.12.2012 12:29:07

You should also read the DateTime Documentation to understand what you can do with it: http://search.cpan.org/perldoc?DateTime

On the Connection startup you can also set which Date object you want.

http://search.cpan.org/perldoc?MongoDB::Connection#dt_type

If you set it to DateTime::Tiny for example it will be faster. But you should first understand the difference between DateTime and DateTime::Tiny. Read the Documentation of booth and decide in which case the one or the other is better.

The example above creates the client time. If you want the time from the server instead of your client, because client/server are not the same. You can do two things.

At first, create a JavaScript function that returns a Date object und evaluate the function on the server.

# JavaScript function that return a Date objectmy $now = MongoDB::Code->new(code => qq{function(){    return new Date}});# later...my $oid = $log->insert({     dt => $dt,    st => $db->eval($now),});

The second possibility. The default "_id" object from MongoDB already contains a timestamp when the object will be created. At least the documentation says it comes from the server, and i hope it really comes from the server and will not created by the driver. But if $entry is your MongoDB result you can get a DateTime object from it this way:

my $dt = DateTime->from_epoch(epoch => $entry->{_id}->get_time);

Example:

#!/usr/bin/env perluse strict;use warnings;use MongoDB;use MongoDB::OID;use MongoDB::Code;use DateTime;# database connection & collectionmy $conn  = MongoDB::Connection->new;my $db    = $conn->dates;my $log = $db->log;# Delete Collection$log->drop;# Client Timemy $dt = DateTime->now;# JavaScript function that return a Date objectmy $now = MongoDB::Code->new(code => qq{function(){    return new Date}});# wait 2 seconds to see a difference between# $dt and the $now functionsleep 2;# Insert one$log->insert({     dt => $dt,    st => $db->eval($now),});sleep 2;$log->insert({     dt => $dt,    st => $db->eval($now),});# Show allmy $dtf = "dd.MM.yyyy HH:mm:ss";my $all = $log->find;while ( my $entry = $all->next ) {    printf "dt: %s\n", $entry->{dt}->format_cldr($dtf);    printf "st: %s\n", $entry->{st}->format_cldr($dtf);    printf "_id time: %s\n", DateTime->from_epoch(epoch => $entry->{_id}->get_time)->format_cldr($dtf);    print "\n";}

Output:

dt: 14.12.2012 16:29:28st: 14.12.2012 16:29:30_id time: 14.12.2012 16:29:30dt: 14.12.2012 16:29:28st: 14.12.2012 16:29:32_id time: 14.12.2012 16:29:32