Hacks 1917 Industrial.. Strength Tips and Tools [Electronic resources] نسخه متنی

Hack 84 Retrieve Details About an Auction

Use the GetItem API call to get listing
details.

The GetItem API call is used to retrieve all the
details of a listing, including the title, description, starting
price, category, and about 180 other individual bits of information.

Here's a simple script that, when provided with the
item number, returns the title, seller ID, amount of time left,
number of bids, and the current price.

#!/usr/bin/perl
require 'ebay.pl';
$item_id = shift @ARGV or die "Usage: $0 itemnumber";
my $rsp = call_api({ Verb => 'GetItem',     [1]
DetailLevel => 0,
Id => $item_id
});
if ($rsp->{Errors}) {
print_error($rsp)
} else {
my %i = %{$rsp->{Item}[0]};
my ($price, $currency, $bids, $time_left, $seller, $title) =     [2]
@i{qw/CurrentPrice CurrencyId BidCount TimeLeft Seller Title/};
$d = $time_left->{Days};     [3]
$h = $time_left->{Hours};
$m = $time_left->{Minutes};
$s = $time_left->{Seconds};
$seller_id = $seller->{User}{UserId};
$seller_fb = $seller->{User}{Feedback}{Score};
print "Item #$item_id: $title\n";
print "For sale by $seller_id ($seller_fb)\n";
print "Currently at $currency$price, $bids bids\n";
if ($d > 0) { print "$d days, $h hours left.\n"; }
elsif ($h > 0) { print "$h hours, $m minutes left.\n"; }
elsif ($s > 0) { print "$m minutes, $s seconds left.\n"; }
else { print "auction ended.\n"; }
}

This script is fairly straightforward. The GetItem
API call is submitted on line [1], and the desired fields
are extracted on line [2]. Naturally,
you can specify any of the 180+ field names specified in the API
documentation (look up GetItem Return Values in the
index), as long as the variables on the left side of the equals sign
on line [2] match up with the field names on
the right.

Note that some variables are hashes (which eBay calls container
nodes), from which relevant data must be extracted. For instance, in
the documentation you'll see entries for
TimeLeft as well as
TimeLeft.Days, TimeLeft.Hours,
TimeLeft.Minutes, and
TimeLeft.Seconds. In Perl, these elements of the
hash are accessed with the -> arrow (infix
dereference) operator, as shown on line [3].

8.4.1 Using the Script

To use the script, simply specify the item number, like this:

getitem.pl 3136272129

and you'll get output like this:

Item #3136272129: Little Red Steam Shovel
For sale by ebayhacker
Currently at $71.00, 9 bids
1 days, 22 hours left.

However, you'll find it much more useful when used
in conjunction with other scripts, like the ones in [Hack #85] and [Hack #87].

8.4.2 DetailLevel

The DetailLevel field in the API call on line
[1] determines how much information is
retrieved. In most cases, a value of 0 is
sufficient. However, if you want to retrieve the description,
you'll need to raise this to at least
2. See [Hack #90]
for an example.

Provided that you're the seller or the high bidder
and the auction is completed, you can retrieve the
HighBidder.User.Email and
Seller.User.Email fields by specifying a detail
level of at least 8, as shown in [Hack #87].

The DetailLevel tag is used for most API calls,
but its usage isn't necessarily the same for all of
them. In most cases, a higher detail level will result in more data
received (and more time taken), but for some API calls, a high detail
level (usually 32 and above) is used for special
"abbreviated" result sets.
Regardless, if you're not getting the results you
expect from an API call, make sure you supply the appropriate
DetailLevel, as instructed by the API
documentation.