Question

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How can I pass an anonymous type to a method?

I want to pass the collection of LINQ result to another method

This is the LinQ code

var sets =
        from a in patient
        from b in patient
        from c in patient
        from d in patient
        from l in patient
        where a.VisitNum < b.VisitNum && b.VisitNum < c.VisitNum && c.VisitNum < d.VisitNum && d.VisitNum < l.VisitNum
        select new { a, b, c, d, l };

The query present the result like this “combinations”

   ID    Visit DAte       Visit number    Rational 
    -------------------------------------------------
   a- 1     14/05/2011           1           new
   b- 1     15/06/2012           2           Emergency 
   c- 1     17/07/2012           3           Check-Up

   a- 1     14/05/2011           1           new
   b- 1     15/06/2012           2           Emergency 
   c- 1     18/12/2012           5           Check-Up

Answer 1

new { a, b, c, d, l } creates an item of anonymous type so return value of entire LINQ query results in an anonymous type as well. To pass such value in a method I would suggest converting it to a known type. Just introduce a new class and an interface if you would like abstract a method from a concrete implementation:

It is not clear what query does and which item types are so update class and type names accordingly:

interface IResultSet
{
   TypeA A { get; }
   TypeB B { get; }
   TypeC C { get; }
   TypeD D { get; }
   TypeL L { get; }
}

class ResultSet : IResultSet
{
   public ResultSet(inject all property values here) {}

   public TypeA A { get; private set; }
   public TypeB B { get; private set; }
   public TypeC C { get; private set; }
   public TypeD D { get; private set; }
   public TypeL L { get; private set; }
}

IEnumerable<IResultSet> sets =
    from a in patient
    from b in patient
    from c in patient
    from d in patient
    from l in patient
    where a.VisitNum < b.VisitNum 
          && b.VisitNum < c.VisitNum 
          && c.VisitNum < d.VisitNum 
          && d.VisitNum < l.VisitNum
    select new ResultSet(a, b, c, d, l);

And keep in mind that LINQ Select() has deffered execution so query itself will not be executed until you access result set enumeration, so if you need to execute it immediately just add .ToList() call at the query end:

Deffered:

ProcessData(sets);

Immediate execution:

ProcessData(sets.ToList());

// Now you can pass results in a method like this
public void ProcessData(IEnumerable<IResultSet> items)

And finally I would suggest NOT using dynamic type to abstract such anonymous types, you can use it but in some special cases so it would be adequate decision. In your case it will makes code less readable and broke type safety, dynamic perfectly fits for DSL engines and things to handle dynamic structure data but not to be a silver bullet for those who badly know OOP basics.