Retrieve specific data dump from a file having many dumps in perl - perl

Question

I have appended Data dumps in an already existing dump file in perl. But using eval <> returns only one data dump. I have named the dumps as $project1, $project2 and so on. I need no retrieve $project2 from the dump file. How do i do that?
This is my data dump :
$project1 = {
'projectname1' => [
{
'media_name' => 'Design Sync',
'dssite' => 'gnb',
'area' => 'qa_dap',
'ldap_list' => 'list1',
'replicate_key' => '2',
'user_num' => '4858',
'role' => '1',
'prj_name' => 'DAP_Rep_Test'
},
{
'media_name' => 'Design Sync',
'dssite' => 'noi',
'area' => 'qa_dap',
'ldap_list' => 'list2',
'replicate_key' => '2',
'user_num' => '4858',
'role' => '1',
'prj_name' => 'TAP_Rep_Test'
}
]
};
$project2 = {
'projectname2' => [
{
'media_name => 'B Sync',
'dssite' => 'agr',
'area' => 'qa_dap',
'ldap_list' => 'list1',
'replicate_key' => '2',
'user_num' => '4858',
'role' => '1',
'prj_name' => 'DAP_Rep_Test'
},
{
'media_name' => 'Design Sync',
'dssite' => 'noi',
'area' => 'qa_dap',
'ldap_list' => 'list2',
'replicate_key' => '2',
'user_num' => '4858',
'role' => '1',
'prj_name' => 'DAP_Rep_Test'
}
]
};
How can i get project2 -> projectname2 -> media_name value for 1st brackets {}??
This is my perl code to write dump and retrieve it :
# Print structure to file
open my $out, '>>', 'file_dump' or die $!;
my %hash_val;
$hash_val {projectname} = $arrayref;
print {$out} Data::Dumper->Dump([\%hash_val], ["projectname"]), $/;
close $out;
# Read structure back in again
open my $in, '<', 'file_dump' or die $!;
my $data;
{
local $/; # slurp mode
$data = eval <$in>;
}
close $in;

Answer 1

The useful thing with Data::Dumper is that it lets you print your data structure, which makes it a lot easier to figure out what you need to print.
project2 has [] which denotes an array. In your example it's only one element, so:
$project2 -> projectname2[0]{media_name}
(as noted in the comments by a username I can't type ;p)
You could also do:
foreach my $thing ( #{ $project2 -> {projectname2} } } {
print $thing -> {media_name},"\n";
}
But really - it looks like you're approaching this problem from the wrong direction. Data::Dumper isn't well suited to data import/export. Storable is a way to save - and load - data structures.
If doing so in such a way as to remain readable by outside programs, then it's probably worth looking at something like JSON or XML rather than Dumper. It's a little harder initially, but makes some much more robust and long lasting code.