Question

I am developing a iPhone app using Monotouch. I need to access a Sqlite DB. In my soultion, I have a contracts, data access, business access and UI project. I have two questions:

1. Where should I keep my DB file? Originally, I put it in the data access project. When I compile my business access project it copies the DB file to the output, but when I compile my UI project it does not (UI has a reference to business access which has a ref to data access). I moved it to the UI project, but it feels wrong to keep it there.

2. Where should I keep the connection string to the DB? Is there a concept of config files?

Answer 1

Here is what we do:

We ship a copy of the DB in the application. It is included as Content, Always Copy in the project.

On the user’s machine, it is stored in the special directory Environment.SpecialFolder.Personal.

When the app is started, we check to see if the database exists on the user’s system and, if not, copy it there.

The connection string is just "Data Source=" + sDatabasePath.

Here is a sample of the code that we use for this (I hacked in the connection stuff since we use a homebuilt class for managing the DB, but you should get the idea):

const string DATABASE_FILE_NAME = "MyDB.db3";
bool fSuccess = false;
DbConnection conn = new DbConnection ();

string sApplicationDir = Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.Personal), "MyApplicationSubDir");
if (!Directory.Exists (sApplicationDir)) {
    Directory.CreateDirectory (sApplicationDir);
}

// Generate the directory to the database file
string sDatabaseDir = Path.Combine (sApplicationDir, "Database");
m_sDatabaseDir = sDatabaseDir;

if (!Directory.Exists (sDatabaseDir)) {
    Directory.CreateDirectory (sDatabaseDir);
}

// Generate the path to the database file
string sDatabasePath = Path.Combine (sDatabaseDir, DATABASE_FILE_NAME);
m_sDatabaseFile = sDatabasePath;

// If the file does not not exist
if (!File.Exists (sDatabasePath)) {
    // Copy the base implementation
    File.Copy (Path.Combine (Path.Combine (Environment.CurrentDirectory, "Database"), DATABASE_FILE_NAME), sDatabasePath);
}

// Initialize the DB
conn.ConnectionString = "Data Source=" + sDatabasePath;