Downloading Images from a Website with Scala and rucola

In this article, we will learn how to use Scala and the scalaj-http and rucola libraries to download all the images from a Wikipedia page.

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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:

Import required libraries
Send HTTP request to fetch the Wikipedia page
Parse the page HTML using rucola
Find the table with dog breed data using a CSS selector
Iterate through the table rows
Extract data from each column
Download images and save locally
Print/process extracted data

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

Imports

We need these libraries:

import scalaj.http._
import rucola.expr._
import java.io._

scalaj-http - Sends HTTP requests

rucola - Parses HTML/XML

java.io - File I/O

Send HTTP Request

To download the web page:

val url = "<https://commons.wikimedia.org/wiki/List_of_dog_breeds>"

val response = Http(url)
  .header("User-Agent", "ScalaScraper")
  .asString

response.code match {
  case 200 =>
    // Parse HTML
  case _ =>
    println(s"Error fetching $url")
}

We make a GET request and provide a custom user-agent header.

Parse HTML

To parse the HTML:

val html = XML.loadString(response.body)

The rucola.expr.XML object represents parsed HTML.

Find Breed Table

We use a CSS selector to find the table element:

val table = html >> element("table.wikitable.sortable")

This selects the

tag with the required CSS classes.

Iterate Through Rows

We loop through the rows:

(table >> element("tr")).drop(1).foreach { row =>

  // Extract data

}

We drop the first row and iterate through the

elements.

Extract Column Data

Inside the loop, we get the column data:

val cells = row >> elements("td", "th")

val name = (cells(0) >> element("a")).text
val group = cells(1).text

val localName = (cells(2) >> element("span")).text.getOrElse("")

val img = cells(3) >> element("img")
val photograph = img.attr("src").getOrElse("")

We use text for text and attr() for attributes.

Download Images

To download and save images:

if (photograph.nonEmpty) {

  val imageData = Http(photograph).asBytes

  val file = new File(s"dog_images/$name.jpg")
  new FileOutputStream(file) << imageData

}

We reuse the HTTP client and save the image bytes to a file.

Store Extracted Data

We store the extracted data:

names :+= name
groups :+= group
localNames :+= localName
photographs :+= photograph

The arrays can then be processed as needed.

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

// Imports
import scalaj.http._
import rucola.expr._
import java.io._

// Arrays to store data
val names = ArrayBuffer[String]()
val groups = ArrayBuffer[String]()
val localNames = ArrayBuffer[String]()
val photographs = ArrayBuffer[String]()

// Send HTTP request
val url = "<https://commons.wikimedia.org/wiki/List_of_dog_breeds>"

val response = Http(url)
  .header("User-Agent", "ScalaScraper")
  .asString

response.code match {
  case 200 =>

    // Parse HTML
    val html = XML.loadString(response.body)

    // Find table
    val table = html >> element("table.wikitable.sortable")

    // Iterate rows
    (table >> element("tr")).drop(1).foreach { row =>

      // Get cells
      val cells = row >> elements("td", "th")

      // Extract data
      val name = (cells(0) >> element("a")).text
      val group = cells(1).text

      val localName = (cells(2) >> element("span")).text.getOrElse("")

      val img = cells(3) >> element("img")
      val photograph = img.attr("src").getOrElse("")

      // Download image
      if (photograph.nonEmpty) {

        val imageData = Http(photograph).asBytes

        val file = new File(s"dog_images/$name.jpg")
        new FileOutputStream(file) << imageData

      }

      // Store data
      names :+= name
      groups :+= group
      localNames :+= localName
      photographs :+= photograph

    }

  case _ =>
    println(s"Error fetching $url")
}

This provides a complete Scala solution using scalaj-http and rucola to scrape data and images from HTML tables. The same approach can apply to many websites.

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