How can I include one expression in another expression?

Question

I have a DateRange class that I\'d like to apply to an IQueryable as a where predicate, automatically using the begin and end dates and automatically using an open or closed int

Answer 1

Here's the updated Apply method created after figuring this out.

    public IQueryable Apply( IQueryable source, Expression> dateField )
    {
        Expression predicate;
        if (BeginDate.HasValue)
        {
            if (BeginInclusive)
                predicate = Expression.GreaterThanOrEqual( dateField.Body, Expression.Constant( BeginDate, typeof(DateTime) ) );
            else
                predicate = Expression.GreaterThan( dateField.Body, Expression.Constant( BeginDate, typeof(DateTime) ) );
            source = source.Where( Expression.Lambda>( predicate ) );
        }
        if (EndDate.HasValue)
        {
            if (EndInclusive)
                predicate = Expression.LessThanOrEqual( dateField.Body, Expression.Constant( EndDate, typeof(DateTime) ) );
            else
                predicate = Expression.LessThan( dateField.Body, Expression.Constant( EndDate, typeof(DateTime) ) );
            source = source.Where( Expression.Lambda>( predicate ) );
        }
        return source;
    }

Next, I'll transform it into an extension method, so it can be used like:

DateRange range;
IQueryable q;
q = q.WhereInDateRange( range, x => x.DateField );