我正在尝试使用表达式树编写动态的Linq 2 Sql查询,但是我遇到了一个异常,告诉我System.String
和System.String
类型没有定义小于号和大于号运算符,这让我感到奇怪,这是真的吗?还是我做错了什么?
Expression<Func<SomeDataContextType, string>> codeSelectorExpresion =
x => x.CodeColumn;
var row = Expression.Parameter(typeof(SomeDataContextType), "row");
var expression =
Expression.GreaterThan(
Expression.Invoke(codeSelectorExpression, row),
Expression.Constant("someString", typeof(string)));
//I'm trying to build something like SomeDataContextType.CodeColumn > "someString"