Compare two xml and print the difference using LINQ

Question

I am comparing two xml and I have to print the difference. How can I achieve this using LINQ. I know I can use XML diff patch by Microsoft but I prefer to use LINQ . If you

Answer 1

The operation you want here is a Zip to pair up corresponding elements in your two sequences of books. That operator is being added in .NET 4.0, but we can fake it by using Select to grab the books' indices and joining on that:

var res = from b1 in xml1.Descendants("book")
                         .Select((b, i) => new { b, i })
          join b2 in xml2.Descendants("book")
                         .Select((b, i) => new { b, i })
            on b1.i equals b2.i

We'll then use a second join to compare the values of attributes by name. Note that this is an inner join; if you did want to include attributes missing from one or the other you would have to do quite a bit more work.

          select new
          {
              Row = b1.i,
              Diff = from a1 in b1.b.Attributes()
                     join a2 in b2.b.Attributes()
                       on a1.Name equals a2.Name
                     where a1.Value != a2.Value
                     select new
                     {
                         Name = a1.Name,
                         Value1 = a1.Value,
                         Value2 = a2.Value
                     }
          };

The result will be a nested collection:

foreach (var b in res)
{
    Console.WriteLine("Row {0}: ", b.Row);
    foreach (var d in b.Diff)
        Console.WriteLine(d);
}

Or to get multiple rows per book:

var report = from r in res
             from d in r.Diff
             select new { r.Row, Diff = d };

foreach (var d in report)
    Console.WriteLine(d);

Which reports the following:

{ Row = 0, Diff = { Name = image, Value1 = C01, Value2 = C011 } }
{ Row = 1, Diff = { Name = name, Value1 = ASP.NET, Value2 = ASP.NET 2.0 } }
{ Row = 3, Diff = { Name = id, Value1 = 20507, Value2 = 20508 } }