Scraping Multiple Pages in Scala with HTTP Client and XML Libraries

Oct 15, 2023 · 4 min read

Web scraping is useful to programmatically extract data from websites. Often you need to scrape multiple pages from a site to gather complete information. In this article, we'll see how to scrape multiple pages in Scala using the HTTP client and XML libraries.

Prerequisites

To follow along, you'll need:

  • Basic Scala knowledge
  • SBT build tool
  • HTTP client and XML libraries:
  • libraryDependencies += "org.scala-lang.modules" %% "scala-xml" % "2.0.0"
    libraryDependencies += "org.scalaj" %% "scalaj-http" % "2.4.2"
    

    Import Libraries

    We'll need the following imports:

    import scalaj.http._
    import scala.xml._
    

    Define Base URL

    We'll scrape a blog - https://copyblogger.com/blog/. The page URLs follow a pattern:

    <https://copyblogger.com/blog/>
    <https://copyblogger.com/blog/page/2/>
    <https://copyblogger.com/blog/page/3/>
    

    Let's define the base URL pattern:

    val baseUrl = "<https://copyblogger.com/blog/page/%d/>"
    

    The %d allows us to insert the page number.

    Specify Number of Pages

    Next, we'll specify how many pages to scrape. Let's scrape the first 5 pages:

    val numPages = 5
    

    Loop Through Pages

    We can now loop from 1 to numPages and construct the URL for each page:

    for (page <- 1 to numPages) {
    
      // Construct page URL
      val url = baseUrl.format(page)
    
      // Code to scrape each page
    
    }
    

    Send Request and Parse HTML

    Inside the loop, we'll send a GET request and parse the HTML:

    val response = Http(url).asString
    
    val html = XML.loadString(response.body)
    

    This gives us an XML node to extract data from.

    Extract Data

    Now within the loop we can use XPath expressions to extract data from each page:

    val articles = html \\ "article"
    
    for (article <- articles) {
    
      // Extract data from article
    
      val title = (article \\ "h2[@class='entry-title']") text
      val url = (article \\ "a[@class='entry-title-link']/@href") text
      val author = (article \\ "div[@class='post-author']/a") text
    
      // Print extracted data
      println(s"Title: $title")
      println(s"URL: $url")
      println(s"Author: $author")
    
    }
    

    Full Code

    Our full code to scrape 5 pages is:

    import scalaj.http._
    import scala.xml._
    
    object WebScraper extends App {
    
      val baseUrl = "https://copyblogger.com/blog/page/%d/"
      val numPages = 5
    
      for (page <- 1 to numPages) {
    
        val url = baseUrl.format(page)
    
        val response = Http(url).asString
    
        val html = XML.loadString(response.body)
    
        val articles = html \ "article"
    
        for (article <- articles) {
        
          val title = (article \ "h2[@class='entry-title']") text
          val url = (article \ "a[@class='entry-title-link']/@href") text
          val author = (article \ "div[@class='post-author']/a") text
          
          val categories = (article \ "div[@class='entry-categories']/a") map(_.text)
          
          println(s"Title: $title")
          println(s"URL: $url")  
          println(s"Author: $author")
          println(s"Categories: $categories")
          
        }
    
      }
    
    }

    This allows us to scrape and extract data from multiple pages sequentially. The code can be extended to scrape any number of pages.

    Summary

  • Use a base URL pattern with %d placeholder
  • Loop through pages with for expression
  • Construct each page URL
  • Send request and parse HTML
  • Extract data using XPath expressions
  • Print or store scraped data
  • Web scraping enables collecting large datasets programmatically. With the techniques here, you can scrape and extract information from multiple pages of a website in Scala.

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