[英]How to pass a lambda expression to a method expecting lambda expression?
I have an extension method to get a property name as string:我有一个扩展方法来获取属性名称作为字符串:
public static string GetPropertyName<T, TResult>(this T obj, Expression<Func<T, TResult>> propertyId)
{
return ((MemberExpression)propertyId.Body).Member.Name;
}
Now I have another method, expecting to pass in list (param) of this kind of property lamba expression.现在我有另一种方法,期望传入这种属性lamba表达式的列表(参数)。 I want this new method to reuse the 1st method, but can't figure out how to pass it over
我希望这个新方法可以重用第一种方法,但不知道如何传递它
public string Test<T>(params Expression<Func<T, object>>[] ps)
{
foreach (var p in ps)
{
var howToCodeThis = p.GetPropertyName(dummy => dummy);
expected usage:预期用途:
var result = Test<Something>(request.Sorting
, x => x.prop1
, x => x.prop2
, x => x.prop3
);
Update: Backs answer worked once I change my GetPropertyName to cater for UnaryExpression:更新:一旦我更改了我的 GetPropertyName 以迎合 UnaryExpression,Backs 答案就起作用了:
public static string GetPropertyName<T, TResult>(this T obj, Expression<Func<T, TResult>> propertyId)
{
if (propertyId.Body is MemberExpression)
return ((MemberExpression)propertyId.Body).Member.Name;
if (propertyId.Body is UnaryExpression)
{
var op = ((UnaryExpression)propertyId.Body).Operand;
return ((MemberExpression)op).Member.Name;
}
throw new NotImplementedException(string.Format("GetPropertyName - {0}", propertyId.Body.GetType().FullName));
}
var howToCodeThis = GetPropertyName(default(T), p);
OR或者
var howToCodeThis = default(T).GetPropertyName(p);
But I noteced, you don't use obj
in GetPropertyName method.但我注意到,您没有在 GetPropertyName 方法中使用
obj
。
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