![]() ![]() ![]() But please measure how much time the script is taking, and you’ll understand how rewarding it is ! Go is a statically typed language, so we need a couple of more lines dedicated to variables declaration. This code is a bit longer than what we could do with a language like Python, but as you can see it is still very reasonable. func fetchUrl ( url string, chFailedUrls chan string, chIsFinished chan bool ) Explanations If url cannot be opened, then log it to a dedicated channel. const ( userAgent = "Mozilla/5.0 (Macintosh Intel Mac OS X 10_11_6) " + "AppleWebKit/537.36 (KHTML, like Gecko) " + "Chrome/.143 " + "Safari/537.36" ) // - // fetchUrl opens a url with GET method and sets a custom user agent. */ package main import ( "fmt" "net/http" ) // - // Custom user agent. It’s your turn to write something now ! Final codeĬheck status code for each url and store urls I could notįetch urls concurrently using goroutines. We’re not dealing with HTML results parsing here, since the goal is to focus on the critical point: improving network access performance. Our scraper will basically try to download a list of web pages we’re giving him first, and check it gets a 200 HTTP status code (meaning the server returned an HTML page without an error). If you need to install Go on another platform, feel free to read the official docs. I already made a short tuto about how to install Go on Ubuntu. Go has other advantages, but let’s talk about it in another article ! Install Go On the other hand, Python is an older language and writing a concurrent web scraper in Python can be tricky, even if Python has improved a lot in this regard recently. Go is a modern language which was created with concurrency in mind. This is where Go is a great help !Ĭoncurrent programming is a very complicated field, and Go makes it pretty easy. web page downloading).Ĭonsequently the solution is about downloading the web resources in parallel. Still, parsing optimization is often negligible compared to the real bottleneck, namely network access (i.e. ![]() Parsing can be improved either by reworking your code, or using a more efficient parser like lxml, or allocating more resources to your scraper. speed up the parsing of the information you retrieved (e.g.speed up the web resource download (e.g.When you’re trying to speed up information fetching from the Web (for HTML scraping or even for a mere API consumption), 2 ways of optimization are possible: Yet once you start looking into your scraper’s performance, Python can be somewhat limited and Go is a great alternative ! Why Go ? Python’s simplicity is great for quick prototyping and so many amazing libraries can help you build a scraper and a result parser ( Requests, Beautiful Soup, Scrapy, …). entry-title").Each( func (index int, item *goquery.I’ve been developing Python web scrapers for years now. use CSS selector found with the browser inspector // for each, use index and itemĭoc.Find( "#main article. import standard libraries "fmt" "log" // import third party libraries "/PuerkitoBio/goquery" Each() we also get a numeric index, which starts at 0 and goes as far as we have elements of the selector #main article. The following program will list all articles on my blogs front page, composed of their title and a link to the post. Usually you shouldn't have multiple main() functions inside one directory, but we'll make an exception, because we're beginners, right? Now we can create the example files for the programs listed below. Now let's create our test project, I did that by the following: # confirm my $GOPATH is set Scraping Links of a Page with golang and goQuery In order to get started with goQuery, just run the following in your terminal: go get /PuerkitoBio/goquery Text() for text content of an element and. If you compare the functions, they are very close to jQuery with the. It gives you easy access to the HTML structure of a page and enables you to pick which elements you want to access by attribute or content. Parsing a page with goQuery goQuery is pretty much like jQuery, just for go. It goes to every web page it can find and stores a copy locally.įor this tutorial, you should have go installed and ready to go, as in, your $GOPATH set and the required compiler installed. ![]() In theory, that's a big part of how Google works as a search engine. Web scraping is practically parsing the HTML output of a website and taking the parts you want to use for something. JonathanMH Archive Web Scraping with Golang and goQuery ![]()
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