How to set a property value by reflection in C#?

The System.Reflection namespace in C# provides classes that allow you to obtain information about applications and dynamically add types, values, and objects at runtime. One of the most common uses of reflection is setting property values dynamically when you don't know the property name at compile time.

Reflection allows you to examine various types in an assembly, instantiate these types, perform late binding to methods and properties, and even create new types at runtime.

Syntax

Following is the syntax for setting a property value using reflection −

Type type = obj.GetType();
PropertyInfo property = type.GetProperty("PropertyName");
property.SetValue(obj, value);

Key Reflection Methods

The following methods are commonly used when working with property reflection −

• GetType() − Gets the Type object for the current instance.

• GetProperty(String) − Searches for the public property with the specified name.

• SetValue(Object, Object) − Sets the property value of a specified object.

• GetValue(Object) − Gets the property value from a specified object.

Using GetProperty() and SetValue()

Example

using System;
using System.Reflection;

class User {
   public int Id { get; set; }
   public string Name { get; set; }
}

class Program {
   static void Main(string[] args) {
      User user = new User();
      Type type = user.GetType();
      PropertyInfo prop = type.GetProperty("Name");
      prop.SetValue(user, "Bangalore");
      Console.WriteLine("Name: " + user.Name);
      
      PropertyInfo idProp = type.GetProperty("Id");
      idProp.SetValue(user, 123);
      Console.WriteLine("Id: " + user.Id);
   }
}

The output of the above code is −

Name: Bangalore
Id: 123

Setting Multiple Properties Dynamically

Example

using System;
using System.Reflection;

class Employee {
   public int EmpId { get; set; }
   public string EmpName { get; set; }
   public double Salary { get; set; }
}

class Program {
   static void Main(string[] args) {
      Employee emp = new Employee();
      Type type = emp.GetType();
      
      // Set multiple properties using reflection
      string[] propertyNames = {"EmpId", "EmpName", "Salary"};
      object[] values = {101, "John Doe", 75000.50};
      
      for (int i = 0; i < propertyNames.Length; i++) {
         PropertyInfo prop = type.GetProperty(propertyNames[i]);
         if (prop != null) {
            prop.SetValue(emp, values[i]);
         }
      }
      
      // Display values
      Console.WriteLine($"Employee ID: {emp.EmpId}");
      Console.WriteLine($"Employee Name: {emp.EmpName}");
      Console.WriteLine($"Salary: {emp.Salary}");
   }
}

The output of the above code is −

Employee ID: 101
Employee Name: John Doe
Salary: 75000.5

Setting Properties with Error Handling

Example

using System;
using System.Reflection;

class Product {
   public string ProductName { get; set; }
   public decimal Price { get; set; }
}

class Program {
   static void SetPropertyValue(object obj, string propertyName, object value) {
      try {
         Type type = obj.GetType();
         PropertyInfo prop = type.GetProperty(propertyName);
         
         if (prop == null) {
            Console.WriteLine($"Property '{propertyName}' not found.");
            return;
         }
         
         if (!prop.CanWrite) {
            Console.WriteLine($"Property '{propertyName}' is read-only.");
            return;
         }
         
         prop.SetValue(obj, value);
         Console.WriteLine($"Property '{propertyName}' set successfully.");
      }
      catch (Exception ex) {
         Console.WriteLine($"Error setting property: {ex.Message}");
      }
   }
   
   static void Main(string[] args) {
      Product product = new Product();
      
      SetPropertyValue(product, "ProductName", "Laptop");
      SetPropertyValue(product, "Price", 999.99m);
      SetPropertyValue(product, "InvalidProperty", "Test");
      
      Console.WriteLine($"Product: {product.ProductName}, Price: ${product.Price}");
   }
}

The output of the above code is −

Property 'ProductName' set successfully.
Property 'Price' set successfully.
Property 'InvalidProperty' not found.
Product: Laptop, Price: $999.99

Conclusion

Setting property values using reflection in C# provides powerful runtime flexibility when property names are not known at compile time. Use GetType() to get the object's type, GetProperty() to find the property, and SetValue() to assign the value dynamically.