C#HTML Parser: AngleSharp Library Tutorials

What can the AngleSharp library really do?

Engage in web page data capture of the old driver understand , C processing HTML is like using chopsticks to drink soup - either not, or laborious. At this time AngleSharp library will come in handy, it can be like a butcher's ox like the structure of the web page to split into a clear. For example, want to pick up price data from an e-commerce site, do not have to write complex regular expressions, directly according to the label attributes can be accurately located.

var config = Configuration.Default.WithDefaultLoader(); var context = BrowsingContext.New(config); var context = BrowsingContext.
var context = BrowsingContext.New(config); var document = await context.OpenAsync("Target URL"); var context = BrowsingContext.
var document = await context.OpenAsync("Target URL"); var priceElement = document.QuerySelector("Target URL"); var priceElement = document.QuerySelector("Target URL"); var priceElement = document.
var priceElement = document.QuerySelector("span.product-price"); var priceElement = document.QuerySelector("span.product-price"); var priceElement = document.

Why do proxy IPs and web parsing need CPs?

A lot of newbies are prone to fall into this pit: directly with the real IP crazy request site, the results of the second was blocked. This is like in the supermarket tasting area even ate three big plate still do not buy things, the security guards do not stare at you to stare at who? This time you need to ipipgo proxy IP service to cover, each request for a new "armor", the site wind control system simply can not catch the handle.

Must-have dual-insurance configuration:

var handler = new HttpClientHandler {
    Proxy = new WebProxy("Proxy address provided by ipipgo: port")
}; var httpClient = new HttpClientHandler
var httpClient = new HttpClient(handler); var config = Configuration.
var config = Configuration.Default.WithDefaultLoader().WithRequesters(httpClient);

Real-world tawdry maneuvering techniques

Ever encountered a site with a particularly strong anti-crawler? I'll teach you a trick: use ipipgo's dynamic residential IP + AngleSharp's simulated login. First login in the browser to get a cookie, and then use the cookie and proxy IP binding, the success rate can be increased by more than 80%. Remember to set a reasonable request interval, don't let the server think it's a robot.

Here is a real case: a customer to capture the price data of competing sites, with ipipgo's rotating IP pool with the following code, stable operation of three months have not overturned:

var rotationProxy = new WebProxy("Dynamic Proxy Gateway Address");
var requester = new HttpClientRequester(rotationProxy);
var browsingConfig = Configuration.
    .WithDefaultLoader()
    .WithCookies()
    .WithRequester(requester); var browsingConfig = Configuration.

Guidelines on demining of common problems

Q: Why do I still get blocked after using a proxy?
A: Check three points: 1. proxy IP quality (recommended ipipgo exclusive IP) 2. request header is complete 3. operation interval is regular

Q: What should I do if the parsed data is garbled?
A: In the Configuration add .WithDefaultEncoding(Encoding.UTF8), if it does not work, contact ipipgo technical customer service to check the agent node encoding

Q: What about pages that need to be processed for JavaScript rendering?
A: AngleSharp itself does not execute JS, this time with PuppeteerSharp, remember to give the headless browser also hang ipipgo agent

Three axes of performance optimization

1. Connection pooling: Don't be silly and create a new proxy connection every time, use the Keep-Alive parameter provided by ipipgo.
2. Asynchronous processing: remembering the golden combination of await and ConfigureAwait(false)
3. Memory management: timely release of the Document object, especially when using the proxy to do large-scale collection

// The right way to do it
using (var document = await context.OpenAsync(url))
{
    // Processing logic
}

Hidden benefits of ipipgo

Many users don't realize that when using their home agency services:
- When calling the API to get the latest IP list, remember to add the geo parameter to specify the region
- Enterprise users can apply for exclusive socks5 proxy channel
- In case of CAPTCHA bombing, you can turn on the smart CAPTCHA proxy mode

Finally, a piece of cold knowledge: the author of AngleSharp has been working on the Blazor component recently, so maybe someday you'll be able to run proxies + parsing directly in WebAssembly. But until then, honestly use ipipgo ready-made program is the king, don't whole all those fancy.