C# HtmlDecode Specific tags only

Question

I have a large htmlencoded string and i want decode only specific whitelisted html tags.

Is there a way to do this in c#, WebUtility.HtmlDecode() decodes everything.

Answer 1

A better approach could be to use some html parser like Agilitypack or csquery or Nsoup to find specific elements and decode it in a loop.

check this for links and examples of parsers

Check It, i did it using csquery :

string input = "<span>i am <strong color=blue>very</strong> big <br>man.</span>";
string output = "<span>i am very big 
man.</span>";

var decoded = HttpUtility.HtmlDecode(output);
var encoded =input ; //  HttpUtility.HtmlEncode(decoded);

Console.WriteLine(encoded);
Console.WriteLine(decoded);

var doc=CsQuery.CQ.CreateDocument(decoded);

var paras=doc.Select("strong").Union(doc.Select ("br")) ;

var tags=new List>();
var counter=0;

foreach (var element in paras)
{
    HttpUtility.HtmlEncode(element.OuterHTML).Dump();
    var key ="---" + counter + "---";
    var value= HttpUtility.HtmlDecode(element.OuterHTML);
    var pair= new KeyValuePair(key,value);

    element.OuterHTML = key ;
    tags.Add(pair);
    counter++;
}

var finalstring= HttpUtility.HtmlEncode(doc.Document.Body.InnerHTML);
finalstring.Dump();

foreach (var element in tags)
{
finalstring=finalstring.Replace(element.Key,element.Value);
}

Console.WriteLine(finalstring);