LINQ的问题

[hujiejieda2]

class AAA
{
public int id { get; set; }
}
class Program
{
static void Main(string[] args)
{
var aaa = new AAA();
aaa.id = 123;
Expression param = Expression.Parameter(typeof(AAA), "x");
Expression body = Expression.Property(param, "id");
Expression<Func<AAA, int>> lambda = (Expression<Func<AAA, int>>)Expression.Lambda(body, param);
var x = lambda.Compile().Invoke(aaa);
Console.WriteLine(x);
}
}

就是不让编译，怎么回事？

[threenewbee]

Expression param = Expression.Parameter(typeof(AAA), "x"); Expression body = Expression.Property(param, "id"); => var param = Expression.Parameter(typeof(AAA), "x"); var body = Expression.Property(param, "id");

[骑着蜗牛去爬山]

Expression param = Expression.Parameter(typeof(AAA), "x"); => ParameterExpression param = Expression.Parameter(typeof(AAA), "x");

[catchdream]

这2个都可以，你的错误如下： 错误 2 参数“2”: 无法从“System.Linq.Expressions.Expression”转换为“System.Linq.Expressions.ParameterExpression[]” 所以直接 Expression<Func<AAA, int>> lambda = (Expression<Func<AAA, int>>)Expression.Lambda(body, (ParameterExpression)param); 也可以

[showjim]

Expression<Func<AAA, int>> lambda = x => x.id;

难道楼主想手动模拟编译器行为？

[Kation]

你想要的结果是什么？ 出什么错误？