CocoCrawler 0.1.2

CocoCrawler

Overview

CocoCrawler is an easy to use web crawler, scraper and parser in C#. By combing PuppeteerSharp and AngleSharp it brings the best of both sides, and merges them into an easy to use API.

It provides an simple API to get started

var crawlerEngine = await new CrawlerEngineBuilder()
    .AddPage("https://old.reddit.com/r/csharp", pageOptions => pageOptions
        .ExtractList(containersSelector: "div.thing.link.self", [
            new("Title","a.title"),
            new("Upvotes", "div.score.unvoted"),
            new("Datetime", "time", "datetime"),
            new("Total Comments","a.comments"),
            new("Url","a.title", "href")
        ])
        .AddPagination("span.next-button > a.not-exist", newPage => newPage.ScrollToEnd())
        .AddOutputToConsole()
        .AddOutputToCsvFile("results.csv")
    )
    .ConfigureEngine(options =>
    {
        options.UseHeadlessMode(false);
        options.WithLoggerFactory(loggerFactory);
    })
    .BuildAsync(cancellationToken);

await crawlerEngine.RunAsync(cancellationToken);

This examples starts at page https://old.reddit.com/r/csharp scrapes all the posts, then continues to the next page and scrapes everything again, and on and on.

With this library it's easy to

• Scrape Single Page Apps
• Scrape Listings
• Add pagination
• Alternative to list is open each post and scrape the page and continue with pagination
• Scrape multiple pages in parallel
• Add custom outputs
• Customize Everything

Scraping pages

With each Page (a page a is a single URL job) added it's possible to add a Task. For each Page it's possible to call:

• .ExtractObject(...)
• .ExtractList(...)
• .OpenLinks(...)
• .AddPagination(...)

It's possible to add multiple pages to scrape with the same Tasks.

   var crawlerEngine = await new CrawlerEngineBuilder()
       .AddPages(["https://old.reddit.com/r/csharp", "https://old.reddit.com/r/dotnet"], pageOptions => pageOptions
           .OpenLinks("div.thing.link.self a.bylink.comments", subPageOptions =>
           {
               subPageOptions.ExtractObject([
                       new("Title","div.sitetable.linklisting a.title"),
                       new("Url","div.sitetable.linklisting a.title", "href"),
                       new("Upvotes", "div.sitetable.linklisting div.score.unvoted"),
                       new("Top comment", "div.commentarea div.entry.unvoted div.md"),
               ]);
               subPageOptions.ConfigurePageActions(ops =>
                {
                    ops.ScrollToEnd();
                    ops.Wait(4000);
                });
           })
           .AddPagination("span.next-button > a")
           .AddOutputToConsole()
           .AddOutputToCsvFile("results.csv"))
        .BuildAsync(cancellationToken);

   await crawlerEngine.RunAsync(cancellationToken);

This example starts at https://old.reddit.com/r/csharp and https://old.reddit.com/r/dotnet and opens each post and scrapes the title, url, upvotes and top comment. It also scrolls to the end of the page and waits 4 seconds before scraping the page. And it continues to the next page.

Configuring the Engine

The engine can be configured with the following options:

• UseHeadlessMode(bool headless): If the browser should be headless or not
• WithLoggerFactory(ILoggerFactory loggerFactory): The logger factory to use
• WithUserAgent(string userAgent): The user agent to use
• WithCookies(params Cookie[] cookies): The cookies to use
• TotalPagesToCrawl(int total): The total number of pages to crawl
• WithParallelismDegree(int parallelismDegree) : The number of pages to crawl in parallel

Stopping the engine

The engine stops when the

• The total number of pages to crawl is reached.
• 2 minutes have passed since the last job was added

Extensibility

The library is designed to be extensible. It's possible to add custom IParser, IScheduler and ICrawler implementations.

using the engine builder it's possible to add custom implementations

.ConfigureEngine(options =>
{
    options.WithCrawler(new MyCustomCrawler());
    options.WithScheduler(new MyCustomScheduler());
    options.WithParser(new MyCustomParser());
})

Custom Outputs

It's possible to add custom outputs by implementing the ICrawlOutput interface.

ICrawlOutput.WriteAsync(JObject jObject, CancellationToken cancellationToken); is called for each object that is scraped.