WP7-不允许访问数据库文件

Question

This is my class:

[Table]
public class Question
{
    [Column]
    public bool Sort { get; set; }
    [Column(IsPrimaryKey = true)]
    public int QuestionID { get; set; }
    [Column]
    public int Level { get; set; }
    [Column]
    public string Description { get; set; }
    [Column]
    public string Answer1 { get; set; }
    [Column]
    public string Answer2 { get; set; }
    [Column]
    public string Answer3 { get; set; }
    [Column]
    public string Answer4 { get; set; }
    [Column]
    public string RightAnswer { get; set; }
    [Column]
    public bool Show { get; set; }
}

public class QuestionContext : DataContext
{
    public QuestionContext(string connectionString)
        : base(connectionString)
    {
    }
    public Table<Question> Questions
    {
        get
        {
            return this.GetTable<Question>();
        }
    }
}

I am trying to connect to my existing database:

 private const string ConnectionString = @"appdata:App_Data\QuestionDb.sdf";

public GamePage()
{
    InitializeComponent();

    using (QuestionContext context = new QuestionContext(ConnectionString))
    {

        if (!context.DatabaseExists())
        {
            // create database if it does not exist
            context.CreateDatabase();
        }
        else
        {
            var questions = from o in context.Questions where o.Level == 1 && o.Show == false select o;
            var question = questions.FirstOrDefault();
        }
    }
}

I get error with "Access to the database file is not allowed". I think problem is in my connection string. What's wrong with it? How can I get access to SQLCE database in folder App_Data?

Answer 1

In your app.config add the following

<connectionStrings>
  <add name="DataContext" 
       connectionString="Data source=DataDirectory|Database.sdf;"
       providerName="System.Data.SqlServerCe.4.0"/>
</connectionStrings>

Then get the connectionstring with help from ConfigurationManager. Maybe you need to add a reference to System.Configuration.

private const string ConnectionString = ConfigurationManager.ConnectionStrings["DataContext"].ConnectionString

You can learn more about DataDirectory in ConnectionString here: http://msdn.microsoft.com/en-us/library/cc716756(v=vs.100).aspx

Answer 2

You must compose the connection string like this:

MyDataContext db = new MyDataContext("Data Source = 'appdata:/mydb.sdf'; File Mode = read only;");

The database file will be read only...