手动创建表达式树
本文关键字:表达式 创建 | 更新日期: 2023-09-27 18:25:12
我有类
public class MyModel
{
public MyModel()
{
this.Map = new MyMap();
}
public MyMap Map { get; set; }
}
public class MyMap
{
public string MyProperty1 { get; set; }
public int MyProperty2 { get; set; }
}
如何构建此lambda
Expression<Func<MyModel, string>> exp = m => m.Map.MyProperty1;
手动使用表达式树?
像这样:
var parameter = Expression.Parameter(typeof (MyModel));
var mapProperty = Expression.Property(parameter, "Map");
var myProperty1 = Expression.Property(mapProperty, "MyProperty1");
var exp = Expression.Lambda<Func<MyModel, string>>(myProperty1, parameter);
您可以使用表达式的PropertyOrField方法来完成此操作,下面是我使用您的对象编写的一个快速示例:
var model = new MyModel();
var mapExpr = Expression.PropertyOrField(Expression.Constant(model), "Map");
var propExpr = Expression.PropertyOrField(mapExpr, "MyProperty1");
Expression.Lambda<Func<string>>(propExpr).Compile()(); //Outputs the value of MyProperty1 on the variable called model.