Xml - A Simple Database

Xml is very simple data store. It will occupy very less memory almost like a text file. If you learn to utilize xml features, then you can easily manage your data with the help of xml.

Xml will reduce your programming burden by its simplicity. There is no chance of difficulty in creation and maintenance of an xml database.

All the time, xml gave me a nice experience while handling data. I am very much satisfied with performance of xml. That satisfaction leads me to write this article.

In this Article, we are going to see

• How to create an xml file?
• How to add or write data into an xml file?
• How to read data from an xml file?
• How to update a data which is stored in an xml file?
• How to remove data from an xml file?

We are going to see the answer for above questions briefly. I don't want to go depth. I just want to clarify the basic concepts simply and clearly, by not exceeding few words.

I have not used any mechanism or tool or control. It's similar to read and write of a text file. Here I meant database as a simple Xml file, nothing more than that.

In order to perform those operations we have several classes in C#. But based on my experience, I strongly recommend XmlDocument class for above all operations.

Create

XmlTextWriter class is used to create an Xml file. In this, we just specify the filepath and type of xml encoding.after that, we have to create a root element of xml document.

Ex:

We are going to create an xml file with CustomerDetails as root element

1. XmlTextWriter xtw;
2. xtw = new XmlTextWriter(filepath, Encoding.UTF8);
3. xtw.WriteStartDocument();
4. xtw.WriteStartElement("CustomerDetails");
5. xtw.WriteEndElement();
6. xtw.Close();

Comment for each line

1. //create instance for xmltextwriter.
2. //assign file path and encoding
3. //write start document
4. //create root element
5. //end root element
6. //close file. It is automatically saved.

Note: You have to include System.Xml, System.IO, System.Text Packages in order to use above classes.

Output

<?xml version="1.0" encoding="utf-8"?>

<CustomerDetails />

Write- [insert into database]

We can add data into an xml file by just adding child nodes to the root element. In this, we just create some xml elements and append those elements to the root as a child element and save the xml document.

Before writing, one thing is very important. All the data stored into the xml file will be treated as String only. So we must convert all data types to string.

Ex:

We just add a customer "abc" with address as "xyz,india"

1. XmlDocument xd = new XmlDocument();
2. FileStream lfile = new FileStream(filepath, FileMode.Open);
3. xd.Load(lfile);
4. XmlElement cl = xd.CreateElement("Customer");
5. cl.SetAttribute("Name", "abc");
6. XmlElement na = xd.CreateElement("Address");
7. XmlText natext = xd.CreateTextNode("xyz,india");
8. na.AppendChild(natext);
9. cl.AppendChild(na);
10. xd.DocumentElement.AppendChild(cl);
11. lfile.Close();
12. xd.Save(filepath);

Comment for each line

1. //object creation for XmlDocument class
2. //open an xml file using file stream
3. //load opened file in xml document
4. //create an xml element
5. //set attribute for that element
6. //create an xml element
7. //create text for xml element
8. //append address text to address node
9. //append address node to root element
10. //append root element to xml document
11. //close the file stream
12. //save the xmldocument content to the file

Output

<?xml version="1.0" encoding="utf-8"?>

<CustomerDetails>

<Customer Name="abc">

<Address>xyz,india</Address>

</Customer>

</CustomerDetails>

Read-[fetch data]

We can retrieve data from an xml file using XmlDocument class.here we just retrieve data based on the name of the element.we fetch data as whole and take what we want by navigating through its contents.

This reading will return everything as String only.After reading we must convert the data into its original datatype.

Ex:

Here we just read the address of the customer named as "abc"

1. XmlDocument xdoc= new XmlDocument();
2. FileStream rfile = new FileStream(path, FileMode.Open);
3. xdoc.Load(rfile);
4. String address;
5. XmlNodeList list = xdoc.GetElementsByTagName("Customer");
6. for (int i = 0; i < list.Count; i++)
7. {
8. XmlElement cl = (XmlElement)xdoc.GetElementsByTagName("Customer")[i];
9. XmlElement add = (XmlElement)xdoc.GetElementsByTagName("Address")[i];
10. if ((cl.GetAttribute("Name")) == "abc")
11. {
12. address = add.InnerText;
13. break;
14. }
15. }
16. rfile.Close();