Downloading Images from a Website with Perl and Mojo::DOM

In this article, we will learn how to use Perl and the LWP::UserAgent and Mojo::DOM modules to download all the images from a Wikipedia page.

—-

Overview

The goal is to extract the names, breed groups, local names, and image URLs for all dog breeds listed on this Wikipedia page. We will store the image URLs, download the images and save them to a local folder.

Here are the key steps we will cover:

1. Import required modules
2. Send HTTP request to fetch the Wikipedia page
3. Parse the page HTML using Mojo::DOM
4. Find the table with dog breed data using a CSS selector
5. Iterate through the table rows
6. Extract data from each column
7. Download images and save locally
8. Print/process extracted data

Let's go through each of these steps in detail.

Modules

We need these core modules:

use LWP::UserAgent;
use Mojo::DOM;
use File::Path qw(make_path);

Send HTTP Request

To download the web page:

my $url = '<https://commons.wikimedia.org/wiki/List_of_dog_breeds>';

my $ua = LWP::UserAgent->new;
$ua->agent('PerlScraper');

my $res = $ua->get($url);

We create a user agent object and provide a custom user agent string.

Parse HTML

To parse the HTML:

my $dom = Mojo::DOM->new($res->content);

The $dom object represents parsed HTML.

Find Breed Table

We use a CSS selector to find the table element:

my $table = $dom->find('table.wikitable.sortable')->[0];

This selects the

Iterate Through Rows

We can iterate through the rows like this:

foreach my $row ($table->find('tr')->slice(1)) {

  # Extract data

}

We loop through each

Extract Column Data

Inside the loop, we extract the column data:

my ($name, $group, $local_name, $img) =
  map $_->text, $row->find('td, th')->each;

my $photograph = $img->find('img')->attr('src');

We use text for text and attr for attributes.

Download Images

To download and save images:

if ($photograph) {

  my $img_data = $ua->get($photograph)->content;

  open my $fh, '>', "dog_images/$name.jpg";
  print $fh $img_data;
  close $fh;

}

We reuse the user agent to download the image and save it to a file.

Store Extracted Data

We store the extracted data in arrays:

push @names, $name;
push @groups, $group;
push @local_names, $local_name;
push @photographs, $photograph;

The arrays can then be processed as needed.

And that's it! Here is the full code:

#!/usr/bin/perl

use strict;
use warnings;

use LWP::UserAgent;
use Mojo::DOM;
use File::Path qw(make_path);

# Arrays to store data
my @names;
my @groups;
my @local_names;
my @photographs;

# User agent
my $ua = LWP::UserAgent->new;
$ua->agent('PerlScraper');

# Fetch HTML
my $url = '<https://commons.wikimedia.org/wiki/List_of_dog_breeds>';
my $res = $ua->get($url);

# Parse HTML
my $dom = Mojo::DOM->new($res->content);

# Find table
my $table = $dom->find('table.wikitable.sortable')->[0];

# Iterate rows
foreach my $row ($table->find('tr')->slice(1)) {

  # Extract data
  my ($name, $group, $local_name, $img) =
    map $_->text, $row->find('td, th')->each;

  my $photograph = $img->find('img')->attr('src');

  # Download image
  if ($photograph) {

    my $img_data = $ua->get($photograph)->content;

    open my $fh, '>', "dog_images/$name.jpg";
    print $fh $img_data;
    close $fh;

  }

  # Store data
  push @names, $name;
  push @groups, $group;
  push @local_names, $local_name;
  push @photographs, $photograph;

}

This provides a complete Perl solution using LWP::UserAgent and Mojo::DOM to scrape data and images from HTML tables. The same approach can apply to many websites.

While these examples are great for learning, scraping production-level sites can pose challenges like CAPTCHAs, IP blocks, and bot detection. Rotating proxies and automated CAPTCHA solving can help.

Proxies API offers a simple API for rendering pages with built-in proxy rotation, CAPTCHA solving, and evasion of IP blocks. You can fetch rendered pages in any language without configuring browsers or proxies yourself.

This allows scraping at scale without headaches of IP blocks. Proxies API has a free tier to get started. Check out the API and sign up for an API key to supercharge your web scraping.

With the power of Proxies API combined with Python libraries like Beautiful Soup, you can scrape data at scale without getting blocked.