WPF C# - taking links from page

Question

I want to get webpage's source(HTML) code and then in my WPF, with ItemsControl I want to get just links from that html documents. for example, www.google.com/search?q=stackoverflow that is the url and I want to take all the main links from it's html code. I'm about begginer in C# and what I'm looking for about this question, I can't understand well, that is why I beg you to make me do this in detail. please, I need your help. thanks.

Answer 1

You should check out the HtmlAgilityPack library, it will help you get and filter links from a HTML document :

This is an agile HTML parser that builds a read/write DOM and supports plain XPATH or XSLT (you actually don't HAVE to understand XPATH nor XSLT to use it, don't worry...). It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML.

Once you retrieved all the links from the HTML document with HtmlAgilityPack, you could simply bind the returned links collection (or transform it into something that fits your needs) to your ItemsSource and display them the way you want.

You'll find a lot of different tutorials on the web, here are two of them (don't forget to install HtmlAgilityPack and to define proper namespaces into your cs file, for installing nuget the best way is using nuget as it is recommanded on the codeplex project page) :

• https://stackoverflow.com/a/847051/1014493
• https://web.archive.org/web/20211020001935/https://www.4guysfromrolla.com/articles/011211-1.aspx

Here's an example that you could use to put all link urls into a single listbox and assuming that's everything is placed into your Window code-behind (we are focusing on HtmlAgilityPack and WPF here, not on architectural or design matters ^^)

In your MainWindow.cs :

• First of all define this namespace at the top of you cs file using HtmlAgilityPack;
• Declare a List<string> dependency property which will be the list containing all the displayed links and bound to your Listbox ItemsSource
• Then declare the Click event callback for your button triggering the HTML parsing
• Then declare the GetLinks method being called in your callback

Here's the full code :

public partial class MainWindow : Window
{
    public List<string> Links
    {
        get { return (List<string>)GetValue(LinksProperty); }
        set { SetValue(LinksProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Links.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty LinksProperty =
        DependencyProperty.Register("Links", typeof(List<string>), typeof(MainWindow), new PropertyMetadata(0));

    public MainWindow()
    {
        InitializeComponent();
        DataContext = this;
    }

    private List<string> GetLinks()
    {
        var links = new List<string>();
        HtmlDocument doc = new HtmlDocument();
        doc.Load("YourHtmlFileInHere");
        foreach (HtmlNode link in doc.DocumentNode.SelectNodes("//a[@href]"))
        {
            HtmlAttribute attribute = link.Attributes["href"];
            if (attribute != null)
            {
                links.Add(attribute.Value);
            }
        }
        return links;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        this.Links = this.GetLinks();
    }
}

Finally, you can create a ListBox and a Button to display your links list into your main Window :

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
        </Grid.RowDefinitions>
        <ListBox Grid.Row="0"  ItemsSource="{Binding Path=Links}"></ListBox>
        <Button Grid.Row="1" Content="Get links" Click="Button_Click"></Button>
    </Grid>
</Window>

Of course, this is very basic example, Links list content cannot be updated and using the code behind that way is not the best thing to do. But still, this is a start!