Opening an SQL CE file at runtime with Entity Framework 4

Question

I am getting started with Entity Framework 4, and I an creating a demo app as a learning exercise. The app is a simple documentation builder, and it uses a SQL CE store. Eac

Answer 1

Here is the answer. I simplified my code and ran it on simpler EDM model, Disney Characters. Model has two entities, Character and Child, with a 1:* association between Character and Child. Children are character's kids--pretty simple stuff. I wrote the demo as a console app to keep it as simple as possible.

Complete code in Program.cs is as follows:

class Program
{
    static void Main(string[] args)
    {
        /* See http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/8a89a728-6c8d-4734-98cb-11b196ba11fd */

        // Configure an SQL CE connection string 
        var filePath = @"D:\Users\dcveeneman\Documents\Visual Studio 2010\Demos\SqlCeEf4Demo\SqlCeEf4Demo\DisneyChars.sdf";
        var sqlCeConnectionString = string.Format("Data Source={0}", filePath);

        // Create an EDM connection
        var builder = new EntityConnectionStringBuilder();
        builder.Metadata = "res://*/DisneyChars.csdl|res://*/DisneyChars.ssdl|res://*/DisneyChars.msl";
        builder.Provider = "System.Data.SqlServerCe.3.5";
        builder.ProviderConnectionString = sqlCeConnectionString;
        var edmConnectionString = builder.ToString();
        var edmConnection = new EntityConnection(edmConnectionString);

        // Build and query an ObjectContext
        using (var context = new DisneyCharsContainer(edmConnection))
        {
            var chars = context.Characters;
            foreach(var character in chars)
            {
                Console.WriteLine("Character name: {0}", character.Name);
                foreach(var child in character.Children)
                {
                    Console.WriteLine("Child name: {0}", child.Name);
                }
            }
            Console.ReadLine();
        }
    }
}

Link at the top of the code is to a forum thread that I used to write the code.

Here is the walkthrough: First, create a database connection. Since I am using SQL CE, I don't have a connection string builder--the connection string is simply a path, so I don't need one. Then I use an EntityConnectionStringBuilder to build an entity connection string, and then I use that to build an EntityConnection. Finally, I pass the connection to the constructor for my ObjectContext. I can then use the ObjectContext to query the EDM.

Answer 2

Finding / opening a SQL Server CE database is, for some weird reason, hard to do. Make sure you can make any kind of connection to the DB at all before trying to get it to work with the EF.