PropertyInfo GetValue/SetValue

C# course · Advanced · Lesson 47/83

Learn to read and write property values with PropertyInfo.

PropertyInfo GetValue/SetValue

PropertyInfo holds the metadata of a property. pi.GetValue(obj) reads the property value; pi.SetValue(obj, value) writes it. The value comes as object?.

This lets serializers and ORMs access properties without knowing their types. For example, a serializer calls GetValue for each property and writes the result to a text format. The same approach is used in code generators.

Indexed properties

For indexed properties, GetValue and SetValue take a second parameter: the index array. E.g. pi.GetValue(obj, new object[] { 0 }). This reads the first element of a list-like property.

Indexed properties are rare; for most regular properties GetValue(obj) and SetValue(obj, value) suffice. Serializers usually skip indexed properties because text-based formats expect plain key-value pairs.

Exercise Read and write a property value

In the Person class below, get the Name property with PropertyInfo pi = typeof(Person).GetProperty("Name");. Write a value with pi.SetValue(p, "Ayşe");. Read it with pi.GetValue(p) and print with Console.WriteLine.

Show example solution

Get the property with PropertyInfo pi = typeof(Person).GetProperty("Name");. Write the value with pi.SetValue(p, "Ayşe");. Read and print with Console.WriteLine(pi.GetValue(p));.
Example solution:
using System;
using System.Reflection;

class Person
{
    public string Name { get; set; } = "Initial";
}

class Program
{
    static void Main()
    {
        Person p = new Person();
        PropertyInfo pi = typeof(Person).GetProperty("Name");
        pi.SetValue(p, "Ayşe");
        Console.WriteLine(pi.GetValue(p));
    }
}

Test yourself

Complete the GetValue call

object val = pi.____(obj);

Show answer

object val = pi.GetValue(obj);

How many parameters does SetValue take?
- Only one (value)
- Two (instance and value)
- Three (instance, value and type)
- None
Show answer

Two (instance and value) — Correct. SetValue takes two parameters: instance and value.
Match the method to its action

GetValue

Reads
SetValue

Writes
GetMethod

Gets a method
GetField

Gets a field

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PropertyInfo GetValue/SetValue