Can I create an anonymous type collection from a DataReader?

c#, datareader

Solution

You can create helper generic method and let compiler infer type parameter:

private IEnumerable<T> Select<T>(DbDataReader reader, Func<DbDataReader, T> selector)
{
    while(reader.Read())
    {
        yield return selector(reader);
    }
}

usage:

var items = SelectFromReader(reader, r => new { CatName = r.GetString(0), CarDOB = r.GetDateTime(1), CatStatus = r.GetInt32(2) });

You can even make the method an extension method on `DbDataReader`:

public static IEnumerable<T> Select<T>(this DbDataReader reader, Func<DbDataReader, T> selector)
{
    while (reader.Read())
    {
        yield return selector(reader);
    }
}

and use it like that:

var items = reader.Select(r => new { CatName = r.GetString(0), CarDOB = r.GetDateTime(1), CatStatus = r.GetInt32(2) });

Problem

I have this code: ``` var query = "SELECT * FROM Cats"; var conn = new SqlConnection(sqlConnectionString); conn.Open(); var cmd = new SqlCommand(query); var reader = cmd.ExecuteReader(); while (reader.Read()) { var CatName = reader.GetString(0); var CatDOB = reader.GetDateTime(1); var CatStatus = reader.GetInt32(2); } ``` I'd like to pull the rows out into an anonymous type collection, which I'd normally do using LINQ to iterate, but I an not sure if it's possible due to the way you have to call `.Read()` each time to get the next row. Is there a way to do this?

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