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I'm working on a small project with dBase files from a 3rd party. Realizing that most of the code to fetch tables and form objects is the same, I made this function:

public static IEnumerable<T> OleDbFetch<T>(Func<OleDbDataReader, T> formator, string connectionString, string query)
{
    var conn = new OleDbConnection(connectionString);
    conn.Open();
    var cmd = new OleDbCommand(query, conn);
    var reader = cmd.ExecuteReader();
    while (reader.Read())
        yield return formator(reader);
    conn.Close();
}

That way I can use it with all sorts of classes (pre-made, imposed) that have mostly parameter-less constructors:

class Person
{
    public int ID { get; set; }
    public string Name { get; set; }

    public Person() { }
}

//...

var persons = OleDbFetch<Person>(
    r => new Person()
    { 
        ID = Convert.ToInt32(r["ID"]), 
        Name = r["Name"].ToString() 
    }, 
    connString, "SELECT ID, Name FROM Person");

Am I missing something obvious, being reckless, or giving myself too much trouble?

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1
  • \$\begingroup\$ I guess I should secure the connection... Make sure it's open. \$\endgroup\$
    – MPelletier
    Commented Nov 10, 2011 at 2:48

1 Answer 1

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Dispose() of types that implement IDisposable with using blocks:

using (var conn = new OleDbConnection(connectionString))
{
    conn.Open();
    using (var cmd = new OleDbCommand(query, conn))
    using (var reader = cmd.ExecuteReader())
    {
        while (reader.Read())
            yield return formator(reader);
    }
}
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1
  • \$\begingroup\$ I'm a sucker for explicitly closing connections... \$\endgroup\$
    – MPelletier
    Commented Nov 10, 2011 at 3:50

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