Fetch a value from an array in a MongoDB collection - mongodb

Question

Below is my MongoDB collection
{
"_id" : ObjectId("5b2a2ee19d332d0118b26dfe"),
"Name" : "Rock",
"Job" : [
{
"Id" : ObjectId("5b2b93c63629d0271ce366ae"),
"JobName" : "abc",
"JobTrack" : [
"123"
]
}
]
}
I want to fetch both ObjectId values
my $cursor = $custColl->find(
{ 'Job.JobName' => "abc", 'Job.JobTrack' => "123" },
{ '_id' => 1, 'Job.Id' => 1 }
);
while ( my $next = $cursor->next ) {
my $CustomerId = "$next->{_id}";
my $JobId = "$next->{'Job.Id'}";
say "$CustomerId => $JobId\n";
}
The result I got from above code as follows
5b2a2ee19d332d0118b26dfe =>
With this code I'm not able to get $JobId.

Answer 1

Assuming the query finds a document, $next is a Perl data structure that resembles your original JSON:
{
'Name' => 'Rock',
'_id' => bless( {
'value' => '5b2a2ee19d332d0118b26dfe'
}, 'MongoDB::OID' ),
'Job' => [
{
'JobName' => 'abc',
'JobTrack' => [
'123'
],
'Id' => bless( {
'value' => '5b2b93c63629d0271ce366ae'
}, 'MongoDB::OID' )
}
]
}
To get the job ID, you need to dereference that structure using Perl syntax, not MongoDB syntax:
my $JobId = "$next->{Job}[0]{Id}";

Answer 2

You need to access a specific element of the Job array. Because there is only one element in your example it must have an index of zero. Accordingly you need
my $JobId = "$next->{'Job.0.Id'}";