goelasticsearchweb-scrapinggo-colly

go-colly: How can I get HTML title in c.OnResponse, so I can fill the struct?


How can I get HTML.title in c.OnResponse - or is there a better alternative to fill the Struct with url/title/content

type WebPage struct {
    Url     string `json:"url"`
    Title   string `json:"title"`
    Content string `json:"content"`
}
    // Print the response
    c.OnResponse(func(r *colly.Response) {
        pageCount++
        log.Println(r.Headers)


        webpage := WebPage{
            Url:     r.Ctx.Get("url"), //- can be put in ctx c.OnRequest, and r.Ctx.Get("url")
            Title:   "my title", //string(r.title), // Where to get this?
            Content: string(r.Body),  //string(r.Body) - can be done in c.OnResponse
        }

        enc := json.NewEncoder(os.Stdout)
        enc.SetIndent("", "  ")
        enc.Encode(webpage) // SEND it to elasticsearch 

        log.Println(fmt.Sprintf("%d  DONE Visiting : %s", pageCount, urlVisited))

    })


I can get title in method like below, however Ctx is not available so I cant put the "title" value in Ctx. Other options?

    c.OnHTML("title", func(e *colly.HTMLElement) {
        fmt.Println(e.Text)
        e.Ctx.Put("title", e.Text) // NOT ACCESSIBLE!
    })

Logs

2020/05/07 17:42:37 7  DONE Visiting : https://www.coursera.org/learn/build-portfolio-website-html-css
{
  "url": "https://www.coursera.org/learn/build-portfolio-website-html-css",
  "title": "my page title",
  "content": "page html body bla "
}
2020/05/07 17:42:37 8  DONE Visiting : https://www.coursera.org/learn/build-portfolio-website-html-css
{
  "url": "https://www.coursera.org/browse/social-sciences",
  "title": "my page title",
  "content": "page html body bla "
}

Solution

  • I created a global variable of that struct and kept filling it in different methods

    Not sure if this is the best way.

    
    fun  main(){
    ....
    
        webpage := WebPage{} //Is this a right way to declare a mutable struct?
    
        c.OnRequest(func(r *colly.Request) { // url
            webpage.Url = r.URL.String() // Is this the right way to mutate?
    
        })
    
        c.OnResponse(func(r *colly.Response) { //get body
            pageCount++
            log.Println(fmt.Sprintf("%d  DONE Visiting : %s", pageCount, webpage.Url))
    
        })
    
        c.OnHTML("head title", func(e *colly.HTMLElement) { // Title
            webpage.Title = e.Text
        })
        c.OnHTML("html body", func(e *colly.HTMLElement) { // Body / content
            webpage.Content = e.Text  // Can url title body be misrepresented in multithread scenario?
        })
    
        c.OnHTML("a[href]", func(e *colly.HTMLElement) { // href , callback
            link := e.Attr("href")
            e.Request.Visit(link)
        })
    
        c.OnError(func(r *colly.Response, err error) { // Set error handler
            log.Println("Request URL:", r.Request.URL, "failed with response:", r, "\nError:", err)
        })
    
        c.OnScraped(func(r *colly.Response) { // DONE
            enc := json.NewEncoder(os.Stdout)
            enc.SetIndent("", "  ")
            enc.Encode(webpage)
        })