c# - Expression.Call 中的 ToUpper()

Question

下面的代码有效，但我想介绍一个 ToUpper()

var predicate =
    Expression.Lambda<Func<T, bool>>(
        Expression.Call(
            Expression.PropertyOrField(parameter, "FirstName"),
            "Contains", null,
            Expression.Constant("myvalue".ToUpper())), parameter
        );

结果是:

{Param_0 => Param_0.FirstName.Contains("MYVALUE")}

但我想要这样:

{Param_0 => Param_0.FirstName.ToUpper().Contains("MYVALUE")}

我该如何改变？

Answer 1

只需添加一个Expression.Call:

var predicate =
    Expression.Lambda<Func<T, bool>>(
        Expression.Call(
            Expression.Call( // <=== this one is new
                Expression.PropertyOrField(parameter, "FirstName"),
                "ToUpper", null),
            "Contains", null,
            Expression.Constant("myvalue".ToUpper())), parameter
        );

然后报告自己为:

Param_0 => Param_0.FirstName.ToUpper().Contains("MYVALUE")