How to initialize child class from instance of parent class.md

Problem

Initialize a child class with all properties values of a parent class

Details

Suppose you have a parent class Product with some attributes e.g. string Name, string Category, string Description, string SKU

There is child class BrandProduct which inherits all attributes from Product and extends it by setting a string Branch based on some conditions

You have method public BrandProduct SetProduct(Product product) which takes Product and return as BrandProduct by setting its brand with some business logic

Once solution could be to set each property from Parent class to child class one by one in SetProduct() function

public BrandProduct SetProduct(Product product) {

    BrandProduct brandProduct = new BrandProduct();

    brandProduct.Name = product.Name;
    brandProduct.Description = product.Description;
    ....and so on

    brandProduct.Brand = //your logic to set this;
}

But you may endup setting 10s of properties one by one. But what if there are some additional properites added in Parten class but you forgot to add mapping here?

Solution

This problem can be handled by creating an extention method, but the best would be to set these mapping in constructor

Sample Code

Product.cs

public class Product
    {
        public string Name { get; }
        public string Description { get; }
        public string Category { get; }
        public string SKU { get; }

        // Public constructor for Parent class initialization

        public Product(string name, string description, string category, string sku)
        {
            this.Name = name;
            this.Description = description;
            this.Category = category;
            this.SKU = sku;
        }

        // Protected constructor to be initialized by Child classes only

        protected Product(Product product)
        {
            this.Name = product.Name;
            this.Description = product.Description;
            this.Category = product.Category;
            this.SKU = product.SKU
        }
    }

BrandProduct.cs

public class BrandProduct : Product
    {
        public string Brand { get; set; }

        public BrandProduct(Product product): base(product)
        {
            
        }
    }

Implementation

public BrandProduct SetProduct(Product product) {

    //initialize child class with instance of parent
    BrandProduct brandProduct = new BrandProduct(product);

    brandProduct.Brand = //your logic to set this;
}

Environment

Visual Studio 2022, .Net 6, C#,