IQueryable extension method for linq2entities

Question

I am trying to implement an extension method that will work with linq2entities. I had initially assumed that if my extension method took and returned an IQueryable, and as

Answer 1

Instead of using expressions e.g.

Expression> IsCurrent = (p)
    => p.Ends > DateTime.Now && p.Starts <= DateTime.Now;

var query = db.PersonHistories.Where(IsCurrent);

You can define extension methods such as:

public static IsCurrent Func<
    IQueryable, DateTime, IQueryable
    >()
{
    return (IQueryable query, DateTime referenceDate) =>
        query.Where(p.Ends > referenceDate && p.Starts <= referenceDate);
}

The use it like this:

var query = IsCurrent();

var results = query(context.PeoplesHistory, referenceDate);

Or:

var results = query(previousResults, referenceDate);

Or alternatively:

public static IsCurrent Func, IQueryable>(
    DateTime referenceDate)
{
    return (IQueryable query) =>
        query.Where(p.Ends > referenceDate && p.Starts <= referenceDate);
}

var query = IsCurrent(refernceDate);

var results = query(context.PeoplesHistory);

That way you don't need a framework for building expressions.