Re: Creating a MongoDB::OID object from the _id field returned by a Perl find_one query

[Stephen Steneker]

I want to extract the timestamp from a MongoDB document's _id field in Perl.  I've been trying to create a MongoDB::OID object from the _id string returned by a find_one, but it complains about illegal hexadecimal digits.  What am I doing wrong?

my $object = $inventoryColl->find_one();
my $objID = MongoDB::OID->new(value => $object->{_id});
my $time = $objID->get_time;   # this line produces an error
my $date = DateTime->from_epoch(epoch => $objID->get_time);  # also produces error

Hi,

Assuming your _id is an ObjectID and not a custom string value, it should already returned as a MongoDB::OID.

So this should work:

my $object = $inventoryColl->find_one();

my $objID = $object->{'_id'};

my $date = DateTime->from_epoch(epoch => $objID->get_time);

print "date: $date\n";

If you're not sure what is being returned, Data::Dumper will show you the contents of a variable without stringifying:

  http://search.cpan.org/dist/Data-Dumper/

Cheers,

Stephen

[Steven Hirschorn]

Thanks Stephen,

Turns out the particular collection I was looking at had a custom _id field.  When I tried against a db with a Mongo-created _id field everything worked.  Thanks for your response.#