Windows Phone 7 – Simple database example

ndlli

　　http://rongchaua.net/blog/windows-phone-7-simple-database-example/
　　Today when I start to play around with developing on Windows Phone 7, I would like to write a first small database application because Windows Phone does not support SQL Server any more. Therefore I must use either LINQ over XML or store the database somewhere on server/Windows Azure and provide services so that the client can access and make query to get and update data. In this small example, I would like to work with LINQ To XML to create a database and update it.
　　My data object (data entity) is a class of Student with his first name, last name and email built by appending first name and last name as describing below



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01	public class Student

02

{

03	public string EMail { get; set; }

04	public string FirstName { get; set; }

05	public string LastName { get; set; }

06

07	public Student(string FirstName, string LastName)

08

{

09	this.FirstName = FirstName;

10	this.LastName = LastName;

11	EMail = FirstName + "@" + LastName + ".com";

12

}

13

14	public Student(XElement xElement)

15

{

16	EMail = xElement.Attribute("EMail").Value;

17	FirstName = xElement.Element("FirstName").Value;

18	LastName = xElement.Element("LastName").Value;

19

}

20

21	public XElement Information

22

{

23

get

24

{

25	return new XElement("Student",

26	new XAttribute("EMail", EMail),

27	new XElement("FirstName", FirstName),

28	new XElement("LastName", LastName));

29

}

30

}

31

}

　　Then I create a sample database with some predefined students



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01

02

03

04

Lewis

05

Franklin

06

07

08

Whitcomb

09

Donald

10

11

12

Kadi

13

Wadad

14

15

　　This database will be loaded into a list of student. Everytime when I add a new student, the new one will be added in this list and the list will be flushed back into XML database. However the predefined database locates outside the management field of application therefore we have no right to write data back. To write data back to XML file, I must store it in isolated storage of application and work with this replication.



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01	public class StudentList : List

02

{

03	public void Load(string strXMLFile)

04

{

05	IsolatedStorageFile isfData = IsolatedStorageFile.GetUserStoreForApplication();

06	XDocument doc = null;

07	IsolatedStorageFileStream isfStream = null;

08	if (isfData.FileExists(strXMLFile))

09

{

10	isfStream = new IsolatedStorageFileStream(strXMLFile, FileMode.Open, isfData);

11	doc = XDocument.Load(isfStream);

12	isfStream.Close();

13

}

14

else

15

{

16	doc = XDocument.Load(strXMLFile);

17	isfStream = new IsolatedStorageFileStream(strXMLFile, FileMode.CreateNew, isfData);

18	doc.Save(isfStream);

19	isfStream.Close();

20

}

21

22	var vStudent = from s in doc.Descendants("Student")

23	select new Student(s);

24	this.Clear();

25	AddRange(vStudent);

26

}

27

28	public void Save(string strXMLFile)

29

{

30

try

31

{

32	XElement xml = new XElement("Students",

33	from p in this

34	select p.Information);

35

36	IsolatedStorageFileStream isfStream = new IsolatedStorageFileStream(strXMLFile, FileMode.Open, IsolatedStorageFile.GetUserStoreForApplication());

37	xml.Save(isfStream);

38	isfStream.Close();

39

}

40	catch (Exception ex)

41

{

42	MessageBox.Show(ex.Message);

43

}

44

}

45

}

　　To work with the database we just need to initialize an object of StudentList and call its methods to manipulate data



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1	private void LoadDatabase()

2

{

3	m_dbList = new StudentList();

4	m_dbList.Load("Database.xml");

5	lvData.ItemsSource = m_dbList;

6

}

　　The complete source code of this example you can download here “Windows Phone Database Example“