ExpandoObject in C#

This article will explain the ExpandoObject in C# with code examples and output.

What is ExpandoObject in C#?

ExpandoObject is a class in C# that provides a way to create objects with dynamic properties at runtime. It belongs to the System.Dynamic namespace. The name "ExpandoObject" is derived from "expandable object," indicating its ability to grow by dynamically adding properties and methods.

The ExpandoObject class implements the IDictionary<string, object> and ICollection<KeyValuePair<string, object>> interfaces, which allow it to behave like a dictionary or a collection of key-value pairs. It provides methods to add, remove, and access properties dynamically.

Once you have added properties to the ExpandoObject, you can access them just like taking things out of a bag. You can read the values of the properties or assign new values to them. It gives you the flexibility to work with data that might change or have an unknown structure.

Key Features of ExpandoObject in C#

Dynamic Property Addition: You can add properties to an ExpandoObject dynamically using the dot notation (expandoObject.PropertyName = value).

using System;
using System.Dynamic;

class Program
{
    static void Main()
    {
        dynamic expandoObject = new ExpandoObject();

        // Adding properties dynamically
        expandoObject.Name = "John";
        expandoObject.Age = 25;

        // Adding a property with a custom getter
        ((IDictionary<string, object>)expandoObject).Add("FullName", "John Doe");
        ((IDictionary<string, object>)expandoObject).Add("Greeting", new Func<string>(() => $"Hello, {expandoObject.FullName}!"));

        Console.WriteLine(expandoObject.Name);
        Console.WriteLine(expandoObject.Age);
        Console.WriteLine(expandoObject.FullName);
        Console.WriteLine(expandoObject.Greeting());
    }
}

Output

Dynamic Property Access: You can access the properties of an ExpandoObject dynamically using the dot notation (expandoObject.PropertyName).

using System;
using System.Dynamic;

class Program
{
    static void Main()
    {
        dynamic employee = new ExpandoObject();

        // Adding properties dynamically
        employee.FirstName = "John";
        employee.LastName = "Doe";
        employee.Age = 30;

        // Accessing properties dynamically
        Console.WriteLine($"Employee: {employee.FirstName} {employee.LastName}");
        Console.WriteLine($"Age: {employee.Age}");

        // Adding and accessing nested properties dynamically
        employee.Address = new ExpandoObject();
        employee.Address.Street = "123 Main St";
        employee.Address.City = "New York";
        employee.Address.Country = "USA";

        Console.WriteLine($"Address: {employee.Address.Street}, {employee.Address.City}, {employee.Address.Country}");
    }
}

Output

Dynamic Property Removal: You can dynamically remove properties from an ExpandoObject using the Remove method of the IDictionary<string, object> interface.

using System;
using System.Dynamic;

class Program
{
    static void Main()
    {
        dynamic expandoObject = new ExpandoObject();

        // Adding properties dynamically
        expandoObject.Name = "John";
        expandoObject.Age = 25;

        // Removing properties dynamically
        ((IDictionary<string, object>)expandoObject).Remove("Name");

        // Accessing properties dynamically
        Console.WriteLine(((IDictionary<string, object>)expandoObject).ContainsKey("Name")); // false
        Console.WriteLine(expandoObject.Age);
    }
}

Output

Dynamic Property Enumeration: You can enumerate the properties of an ExpandoObject using foreach or by treating it as a dictionary or collection.

using System;
using System.Collections.Generic;
using System.Dynamic;

class Program
{
    static void Main()
    {
        dynamic employee = new ExpandoObject();

        // Adding properties dynamically
        employee.FirstName = "John";
        employee.LastName = "Doe";
        employee.Age = 30;

        // Enumerating properties dynamically
        IDictionary<string, object> employeeDictionary = (IDictionary<string, object>)employee;
        foreach (KeyValuePair<string, object> property in employeeDictionary)
        {
            Console.WriteLine($"{property.Key}: {property.Value}");
        }
    }
}

Output

 

Summary

An ExpandoObject is like a flexible bag where you can dynamically add, remove, and access different pieces of information without having a predefined structure. It's useful when you need to work with data that can change or want the freedom to customize objects. Whether working with dynamic APIs, customizing objects at runtime, or dealing with dynamic data transformations, the ExpandoObject can be a valuable tool in your C# programming.

I hope this blog post has provided you with an understanding of ExpandoObject. Feel free to leverage this powerful tool in future projects and let your creativity thrive.

Thank you for reading, and happy coding!".