C# Working with Xml Documents

 

XML is the main file type used to save our program’s data. In this tutorial, I’ll show you how to work with XML files in C#.

I’ll be working with the following file:

<products>

         <product>
                <name>Book</name>
                <price>15$</price>
         </product>

         <product>
                <name>Crayon</name>
                <price>5$</price>
         </product>

</products>

Basics

<products> is the main node.
<product> is a smaller node, found in the main node, each one contains information about a product (its parent is ‘product’)
<name> and <price> are nodes which correspond to product node (parent node: ‘product’).

Ok, now for the coding part, include in the project: using System.Xml;
After this, we create an XmlDocument object - used for opening the xml file:

XmlDocument xmldoc = new XmlDocument();
xmldoc.Load("file.xml");  //open the file

Reading from a node

Before reading the values form our file, we must select the nodes.

If we need to select only one node corresponding to a certain product, the following code must be used:

XmlNode book_node = xmldoc.SelectSingleNode("/products/product[name='Book']"); //selects the node where name is 'Book'

If we need to know the price of the product selected before:

string book_price = book_node["price"].InnerText;

However, it is also possible to select multiple nodes from the file - not just one:

XmlNodeList nodelist = xmldoc.SelectNodes("/products/product");

The code above returns an array containing all the nodes found in products.

Now, we get the values of every node in the list:

foreach (XmlNode node in nodelist)
{
         string name = node["name"].InnerText;
         string price = node["price"].InnerText;
}

Adding a new node

Let’s say we want to add to our file another product, with a custom name & price.
We start by creating the product’s node and attach it to the main node (products):

XmlNode product_node = xmldoc.CreateElement("product");
xmldoc.DocumentElement.AppendChild(product_node);

Having the node, we have to add the other 2 elements (name & price)

XmlNode product_name = xmldoc.CreateElement("name");     
product_node.InnerText = "Pencil"; //set the product's name
product_node.AppendChild(product_name);  //and attach it to the product node

XmlNode product_price = xmldoc.CreateElement("price");     
product_price.InnerText = "9$"; 
nod_produs.AppendChild(product_name);

Deleting a node

A node is ‘deleted’ when it’s removed from its parent node, so if we want to delete the last node from the list - the one that we created before, we use this:

XmlNode node = xmldoc.SelectSingleNode("/products/product[name='Pencil']");  //select node where name is 'Pencil'
node.ParentNode.RemoveChild(node);

Saving the file

Don’t forget to save any changes you made in the xml document:

xmldoc.Save("file.xml");

The end