In C# How to dynamically specify a member of a object, like obj[“abc”] in PHP

问题

Say I have a class

public class Employee
{
    public string name = "";
    public int age = 20;
}

now I want a function that can dynamically get the value of a specified member of Employee

public class Util<T>
{
    public static string GetValue(T obj, string member)
    {
        // how to write
    }
}

so that I can use it like

Employee p1 = new Employee();
string a = Util<Employee>.GetValue(p1, "age"); // a should be "20"

How to do it? like access member use obj["???"] in PHP

回答1:

Reflection. Take a look here:

Reflection: Property Value by Name

Oh, and also here in our very own SO!

Update

Sigh... It's all about "teh codez"... Here you go:

p1.GetType().GetProperty("age").GetValue(p1,null);

But do check the links, there's stuff to learn!

回答2:

yes, it's called Reflection. See Get property value from string using reflection in C#

回答3:

try following code:

// get value of private field: private double _number
int value = (int)typeof(p1).InvokeMember("age",
BindingFlags.GetField | BindingFlags.Instance | BindingFlags.NonPublic,
null, p1, null);

 // Get the FieldInfo of MyClass.
 FieldInfo[] myFields = typeof(p1).GetFields(BindingFlags.Public | BindingFlags.Instance);

 var age = myFields[i].GetValue(p1);

check link for more details

回答4:

Where does the parameter "age" come from? You should think about other designs where the choice of property isn't stored in a string.

For example, if you want to display a drop-down allowing the user to choose a column to sort by, you would want to pass a Comparer<Employee> from the view to the model, this will be much MUCH faster, and also use the correct numeric sort instead of lexicographic.

回答5:

While I see a lot of usage of reflection here, maybe in your usecase you can do

object p1 = new Employee();
var employee = p1 as Employee;
// optionally you could do a nullcheck
string a = employee.age; // a should be "20"

Reflection works, but in your case I would just not go that far. but maybe you need generics then yes, go with reflection instead.

来源：https://stackoverflow.com/questions/5716766/in-c-sharp-how-to-dynamically-specify-a-member-of-a-object-like-objabc-in-p

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