How can I easily convert DataReader to List? [duplicate]

Answer 1

Obviously @Ian Ringrose's central thesis that you should be using a library for this is the best single answer here (hence a +1), but for minimal throwaway or demo code here's a concrete illustration of @SLaks's subtle comment on @Jon Skeet's more granular (+1'd) answer:

public List Load( <> )
{
    using ( var connection = CreateConnection() )
    using ( var command = Create<>Command( <>, connection ) )
    {
        connection.Open();
        using ( var reader = command.ExecuteReader() )
            return reader.Cast()
                .Select( x => new XXX( x.GetString( 0 ), x.GetString( 1 ) ) )
                .ToList();
    }
}

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As in @Jon Skeet's answer, the

            .Select( x => new XXX( x.GetString( 0 ), x.GetString( 1 ) ) )

bit can be extracted into a helper (I like to dump them in the query class):

    public static XXX FromDataRecord( this IDataRecord record)
    {
        return new XXX( record.GetString( 0 ), record.GetString( 1 ) );
    }

and used as:

            .Select( FromDataRecord )

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UPDATE Mar 9 13: See also Some excellent further subtle coding techniques to split out the boilerplate in this answer