API Searches

Perform reliable searches with GetSearchResults.

In [Hack #17], a Perl script is used to perform an automated eBay search and then email new listings as they’re discovered. Although the script serves a valuable function, it has the notable handicap of relying entirely on “scraping” (via the WWW::Search::eBay module) to retrieve its search results.

Scraping involves parsing standard web pages in order to retrieve the desired data. As you might expect, any changes to eBay’s search pages, even minor ones, will break the script until the WWW::Search::eBay module on which it relies is updated to work with the new version.

The API, on the other hand, provides an officially supported interface to eBay’s search engine, which means that scripts based on the API will be much more robust and nearly invulnerable to changes in eBay’s search pages.

A Simple Search

Here’s a simple Perl script, search.pl , that performs a search and displays the results.

#!/usr/bin/perl
require 'ebay.pl';

use Getopt::Std;
getopts('d');
$keywords = shift @ARGV or die "Usage: $0 [-d] keywords";

PAGE:     [1]
while (1) {
my $rsp =  call_api({ Verb => 'GetSearchResults',     [2]
                 DetailLevel => 0,
                       Query => $keywords,
         SearchInDescription => $opt_d ? 1 : 0,
                        Skip => $page_number * 100,
  });
  if ($rsp->{Errors}) {
    print_error($rsp);
    last PAGE;
  }
foreach (@{$rsp->{Search}{Items}{Item}}) {     [3]
    my %i = %$_;
($price, $time, $title, $id) = @i{qw/CurrentPrice EndTime Title Id/};     [4] print "($id) $title [\$$price, ends $time]\n"; ...

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