How do I handle Database Connections with Dapper in .NET?

Question

I\'ve been playing with Dapper, but I\'m not sure of the best way to handle the database connection.

Most examples show the connection object being created in the

Answer 1

I wrap connection with the helper class:

public class ConnectionFactory
{
    private readonly string _connectionName;

    public ConnectionFactory(string connectionName)
    {
        _connectionName = connectionName;
    }

    public IDbConnection NewConnection() => new SqlConnection(_connectionName);

    #region Connection Scopes

    public TResult Scope(Func func)
    {
        using (var connection = NewConnection())
        {
            connection.Open();
            return func(connection);
        }
    }

    public async Task ScopeAsync(Func> funcAsync)
    {
        using (var connection = NewConnection())
        {
            connection.Open();
            return await funcAsync(connection);
        }
    }

    public void Scope(Action func)
    {
        using (var connection = NewConnection())
        {
            connection.Open();
            func(connection);
        }
    }

    public async Task ScopeAsync(Func funcAsync)
    {
        using (var connection = NewConnection())
        {
            connection.Open();
            await funcAsync(connection);
        }
    }

    #endregion Connection Scopes
}

Examples of usage:

public class PostsService
{
    protected IConnectionFactory Connection;

    // Initialization here ..

    public async Task TestPosts_Async()
    {
        // Normal way..
        var posts = Connection.Scope(cnn =>
        {
            var state = PostState.Active;
            return cnn.Query("SELECT * FROM [Posts] WHERE [State] = @state;", new { state });
        });

        // Async way..
        posts = await Connection.ScopeAsync(cnn =>
        {
            var state = PostState.Active;
            return cnn.QueryAsync("SELECT * FROM [Posts] WHERE [State] = @state;", new { state });
        });
    }
}

So I don't have to explicitly open the connection every time. Additionally, you can use it this way for the convenience' sake of the future refactoring:

var posts = Connection.Scope(cnn =>
{
    var state = PostState.Active;
    return cnn.Query($"SELECT * FROM [{TableName()}] WHERE [{nameof(Post.State)}] = @{nameof(state)};", new { state });
});

What is TableName() can be found in this answer.