c# 拼接lambda表达式

public static class PredicateExtensions
    {
        public static Expressionbool>> True()
        {
            return f => true;
        }

        public static Expressionbool>> False()
        {
            return f => false;
        }

        public static Expressionbool>> Or(this Expressionbool>> expression1, Expressionbool>> expression2)
        {
            var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast());
            return Expression.Lambdabool>>(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters);
        }

        public static Expressionbool>> And(this Expressionbool>> expression1, Expressionbool>> expression2)
        {
            var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast());
            return Expression.Lambdabool>>(Expression.And(expression1.Body, invokedExpression), expression1.Parameters);
        }
    }

public ActionResult Index(string keyword)
        {
            string name = "变形金刚";

            decimal price = 20000;

            DateTime dt = Convert.ToDateTime("2019 - 09 - 09");

            Expressionbool>> expression = t => true;

            expression = expression.And(t => t.MName == name);

            expression = expression.And(t => t.MPrice == price);

            expression = expression.And(t => t.ShowTime == dt);

            var ds = db.Movies.Where(expression.Compile()).AsQueryable().ToList();

            return View(ds);
        }