Deduplicate XML using LINQ based on attribute value

Question

I have a XML like this:

<rewriteMaps>
  <rewriteMap name="RewritesInSightContentaltecNL">
    <add key="/tata" value="/productdetails.aspx?id=1628" />
    <add key="/tata" value="/productdetails.aspx?id=1628" />
    <add key="/marc" value="/productdetails.aspx?id=1626" />
    <add key="/marc" value="/productdetails.aspx?id=1626" />
    <add key="/marc" value="/productdetails.aspx?id=1626" />

    <add key="/henk" value="/productdetails.aspx?id=162996" />
    <add key="/henk" value="/productdetails.aspx?id=1aa6" />

    <add key="/tata" value="/productdetails.aspx?id=1628" />
    <add key="/tata" value="/productdetails.aspx?id=1628" />
    <add key="/marc" value="/productdetails.aspx?id=1626" />
    <add key="/marc" value="/productdetails.aspx?id=1626" />
    <add key="/aaaa" value="/productdetails.aspx?id=xxxx" />
  </rewriteMap>

  </rewriteMaps>

From which I want to remove duplicate values base on the "key" attribute"

So I want to end up with:

 <add key="/tata" value="/productdetails.aspx?id=1628" />
 <add key="/marc" value="/productdetails.aspx?id=1626" />
 <add key="/henk" value="/productdetails.aspx?id=162996" />
 <add key="/aaaa" value="/productdetails.aspx?id=xxxx" />

Any help greatly appreciated.

Answer 1

Use Remove extension method.This method will remove all selected nodes from document. Try this code.

xdoc.Root.Elements("add")
.GroupBy(s => (string)s.Element("value"))
.SelectMany(g => g.Skip(1)) // select all nodes from group except first one
.Remove();

Answer 2

XElement rewriteMaps = XElement.Parse(xmlToParse);
var distinct data= rewriteMaps.Descendants("rewriteMap")
                                    .Elements()
                                    .GroupBy(x=> new { key = (string)x.Attribute("key"), value = (string)x.Attribute("value")})
                                    .Select(x=> x.FirstOrDefault());

This will give you

  <add key="/tata" value="/productdetails.aspx?id=1628" /> 
  <add key="/marc" value="/productdetails.aspx?id=1626" /> 
  <add key="/henk" value="/productdetails.aspx?id=162996" /> 
  <add key="/henk" value="/productdetails.aspx?id=1aa6" /> 
  <add key="/aaaa" value="/productdetails.aspx?id=xxxx" />