There are also quite a few other links (e.g. With our Wikipedia page, we'll notice we've got plenty of link in our Table of Contents, we won't need those. This is where your browser's developer tools will shine once again, as they allow you to analyse the DOM tree in detail. HTML Agility Pack is a popular parser suite and can be easily combined with LINQ as well, for example.īefore you parse the HTML, you need to know a little bit about the structure of the page so that you know which elements to extract exactly. With the HTML retrieved, it's time to parse it. If you pick "HTML Visualizer" from the context menu, you'd be getting a preview of the HTML page, but already by hovering over the variable, we can see that we got a proper HTML page returned by the server, so we should be good to go. Visual Studio will stop at the breakpoint and now you can view the current state of the application. You can test the above code by clicking the “Run” button in the Visual Studio menu: This will ensure that you can use the Visual Studio debugger UI to view the results. We still haven’t parsed it yet, but now is a good time to run the code to ensure that the Wikipedia HTML is returned instead of any errors.įor that, we'll first set a breakpoint in the Index() method at return View(). Here, we define our Wikipedia URL in url, it to CallUrl(), and are storing its response in our response variable.Īll right, the code to make the HTTP request is done. Using GetStringAsync(), it's relatively straightforward to get the content of any URL in an asynchronous, non-blocking fashion, as we can observe in the following example. Plus, it supports asynchronous calls out of the box. NET already comes with an HTTP client (aptly named HttpClient) in its namespace, so no need for any external third party libraries or dependencies. Still, let's focus on that particular Wikipedia page for our following examples. In more complex projects, you can crawl pages using the links found on a top category page. This is just one simple example of what you can do with web scraping, but the general concept is to find a site that has the information you need, use C# to scrape the content, and store it for later use. you can easily process with Excel) for later use. You can scrape the list and save the information to a CSV file (which e.g. That article has a list of programmers with links to their respective own Wikipedia pages. It wouldn't be Wikipedia, if it didn't have such an article, right? □ Imagine you have a project where you need to scrape Wikipedia for information on famous software engineers. Making an HTTP Request to a Web Page in C# This package makes it easy to parse the downloaded HTML and find tags and information that you want to save.įinally, before you get started with coding the scraper, you need the following libraries added to the codebase: Install the package, and then you’re ready to go. In NuGet, click the “Browse” tab and then type “HTML Agility Pack” to fetch the package. After you created a new project, use the NuGet package manager to add the necessary libraries used throughout this tutorial. NET Core Web Application project using MVC (Model View Controller). If you’re using C# as a language, you probably already use Visual Studio. NET Core 3.1 framework and the HTML Agility Pack for parsing raw HTML. NET libraries are available to make integration of Headless Chrome easier for developers. The PuppeteerSharp and Selenium WebDriver. Note: This article assumes that the reader is familiar with C# and ASP.NET, as well as HTTP request libraries. This is what we will discuss in the second part of this article, where we will have an in-depth look at PuppeteerSharp, Selenium WebDriver for C#, and Headless Chrome. The moment we are dealing with single-page applications, or anything else that heavily relies on JavaScript, things become a lot more complicated. Specifically, we'll walk you through the steps on how to send the HTTP request, how to parse the received HTML document with C#, and how to access and extract the information we are after.Īs we mentioned in other articles, this will work beautifully as long as we scrape server-rendered/server-composed HTML. In this article, we will cover how to scrape a website using C#. C# is rather popular as backend programming language and you might find yourself in need of it for scraping a web page (or multiple pages).
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