How do I get the max data size of every column in an IQueryable using LINQ

Question

I have a method that takes an IQueryable. Is there a LINQ query that will give me back the size of each column in the IQueryable?

To be more clear: this is Linq-to-objects. I want to get the length of the ToString() of each "column".

Answer 1

It depends. If you mean is there a completely generic way to make this determination the answer is no. All IQueryable will give access to is the Type of each expression. There is no way to arbitrarily map a Type to a column size.

If on the other hand you have the ability to map a Type to members and member type to a column size then yes there is a way to get the size.

public IEnumerable GetColumnSize(IQueryable source)
{
  var types = MapTypeToMembers(source).Select(x => x.Type);
  return types.Select(x => MapTypeToSize(x));
}

Answer 2

I guess you're talking about LINQ-to-SQL. It completely ignores column sizes. varchar(15), char(20) and nvarchar(max) are just strings for it. The overflow error will appear only on the SQL Server side.

Answer 3

You said for each "column", that would map to each property. In Linq to Objects, this should work, although too manual:

var lengths = from o in myObjectCollection
              select new 
              {
                 PropertyLength1 = o.Property1.ToString().Length,
                 PropertyLength2 = o.Property2.ToString().Length,
                 ...
              }

If you meant the ToString() length of each item ("row") in the collection, then:

var lengths = from o in myObjectCollection
              select o.ToString().Length;