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Cannot override default treatment of attributes with a custom IMarkupFormatter

See original GitHub issue

I am using AngleSharp v0.13.0

I am trying to override the default formatting behavior for HTML attributes by using a custom IMarkupFormatter and passing in an override for Attribute(IAttr attribute). However, no matter what I do I can’t seem to get AngleSharp to use the override. For example:

Let’s say I give my IMarkupFormatter the following Attribute method:

public string Attribute(IAttr attribute) => "hello";

I would expect this method to be hit when ParseDocument is called, but instead it hits the default Attribute method and ignores my custom rule. Here is my complete implementation:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PipelineTest
{
    using AngleSharp;
    using AngleSharp.Dom;
    using AngleSharp.Html;
    using AngleSharp.Html.Dom;
    using AngleSharp.Html.Parser;
    using AngleSharp.Xhtml;
    using PreMailer.Net;
    class Program
    {
        static void Main(string[] args)
        {
            RunAnglesharp();
            Console.WriteLine();
        }

        static async Task RunAnglesharp()
        {
            var parser = new HtmlParser(new HtmlParserOptions
            {
                IsNotConsumingCharacterReferences = true,
            });

            var formatter = new SupressEncodingFormatter();
            var document = parser.ParseDocument("<html><head></head><body><a href=\"https://www.foo.com/?h=4&w=8\">&foo</a></body></html>");
            var output = document.ToHtml(formatter);
            Console.WriteLine(output);
            // Expected Output: "<html><head></head><body><a href=\"hello">&foo</a></body></html>"
            // Actual Output: "<html><head></head><body><a href=\"https://www.foo.com/?h=4&amp;w=8\">&foo</a></body></html>"
        }

        class SupressEncodingFormatter : IMarkupFormatter
        {
            public string Attribute(IAttr attribute) => "hello";
            public string CloseTag(IElement element, bool selfClosing) => HtmlMarkupFormatter.Instance.CloseTag(element, selfClosing);
            public string Comment(IComment comment) => HtmlMarkupFormatter.Instance.Comment(comment);
            public string Doctype(IDocumentType doctype) => HtmlMarkupFormatter.Instance.Doctype(doctype);
            public string OpenTag(IElement element, bool selfClosing) => HtmlMarkupFormatter.Instance.OpenTag(element, selfClosing);
            public string Processing(IProcessingInstruction processing) => HtmlMarkupFormatter.Instance.Processing(processing);
            public string Text(ICharacterData text) => text.Data;
        }
    }
}

Issue Analytics

State:
Created 3 years ago
Comments:7 (4 by maintainers)

Top GitHub Comments

1reaction

FlorianRapplcommented, Jan 14, 2021

thanks for the confirmation @bmode . Fixed https://github.com/AngleSharp/anglesharp.github.io/blob/master/_docs/Questions.md

1reaction

CaptainStackcommented, Mar 26, 2020

So as a non-expert on this, I see I kind of misunderstood how it worked. Your comment helped me, I now have a working implementation, I just needed to overload both OpenTag and Attribute, even though Attribute was the only one I really wanted to change.

I think 2 makes a lot of sense to me, when first getting into this I didn’t see why I needed to include the interfaces I wasn’t changing - I was assuming a more traditional inheritance model.

My only hesitation is making this a breaking change as I am now working on an implementation that assumes the current system! Cheers 🍻