traversing a list of objects

patrickrock has asked for the wisdom of the Perl Monks concerning the following question:

when using Net::Amazon::Request::Wishlist the docs state:

"Upon success, the response's properties() method will return a list of Net::Amazon::Property::* objects" So the following code:

use Net::Amazon;
use Net::Amazon::Request::Wishlist;
use Data::Dumper;

$token = 'token';
$wishid = 'wishid';
my $ua = Net::Amazon->new(token => $token);

my $req = Net::Amazon::Request::Wishlist->new(wishlist => $wishid);

# Response is of type Net::Amazon::Response::Wishlist
my $resp = $ua->request($req);
printer Dumper($resp);
[download]

returns this (from the dumper function):

$VAR1 = bless( {
                 'xmlref' => {
                               'Details' => [
                                              {
                                                'ReleaseDate' => '01 F
+ebruary, 2003',
                                                'Upc' => '636920004479
+',
                                                'NumMedia' => '1',
[download]

etc...

What I am unsure about is the syntax I need to traverse this. I know that I am looking at some kind of hash of hashes, but I'm just kind of lost. I feel like I should be able to do something like:

print $resp{xmlref}{Details}{ReleaseDate};

But that doesn't seem to be working. I think I just don't understand the syntax of what to do. Can you guys help?

Comment on traversing a list of objects Select or Download Code

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Re: traversing a list of objects by simonm (Vicar) on Dec 07, 2004 at 21:11 UTC
Perhaps you want `$resp->{xmlref}{Details}[0]{ReleaseDate}`? The arrow means that you want to follow a reference, and the square brackets find array elements. One way you can explore this kind of structure is by using Data::Dumper to show the results of a partial access: `print Dumper( $resp ); print Dumper( $resp->{xmlref} ); print Dumper( $resp->{xmlref}->{Details} );` [download] Check out the perlref manpage for more information on the reference syntax.	[reply] [d/l] [select]
Re: traversing a list of objects by ikegami (Patriarch) on Dec 07, 2004 at 21:27 UTC
$resp is a reference to a hash, not a hash, so `print $resp->{...` or `print $$resp{...` Also, You seem to not have noticed the `[`, so `print $resp->{xmlref}{Details}[$i]{ReleaseDate}` or `print $$resp{xmlref}{Details}[$i]{ReleaseDate}` To print release date of all items: `print($_->{ReleaseDate}, $/) foreach (@{$$resp{xmlref}{Details}});` [download] To store the release dates of all items into an array: `@release_dates = map { $_->{ReleaseDate} } @{$$resp{xmlref}{Details}};` [download]	[reply] [d/l] [select]
Re^2: traversing a list of objects by dragonchild (Archbishop) on Dec 08, 2004 at 13:32 UTC
print $$resp{... I really really dislike that syntax. In large part because it's sooo Perl4. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply]
Re: traversing a list of objects by BrowserUk (Patriarch) on Dec 07, 2004 at 21:13 UTC
Try `print $resp->{xmlref}{Details}{ReleaseDate};` [download] And then read references quick reference (Re: push) Examine what is said, not who speaks. "But you should never overestimate the ingenuity of the sceptics to come up with a counter-argument." -Myles Allen "Think for yourself!" - Abigail "Time is a poor substitute for thought"--theorbtwo "Efficiency is intelligent laziness." -David Dunham "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon	[reply] [d/l]
Re: traversing a list of objects by IOrdy (Friar) on Dec 08, 2004 at 13:20 UTC
I might be missing the point but why are you poking around the internals of the object? The docs for Net::Amazon::Response shows that properties() returns an array of objects (each of which is a Net::Amazon::Property::* object I guess) `if($resp->is_success) { foreach my $property ($resp->properties) { # $property isa Net::Amazon::Property object # print $property->as_string, $/; print $property->ProductName, ' ', $property->ReleaseDate, $/; } }` [download]	[reply] [d/l]