From: Travis Whitton <whitton@...>
Date: 2002-09-27T01:35:26+09:00
Subject: Weird Array.flatten behaviour with DBI

Hello, I'm having a weird issue with the Array.flatten method when using
it with DBI. The problem is that it doesn't seem to flatten out results
returned from sth.fetch_all. I rolled my own flatten, but I'd rather
use Ruby's builtin flatten. Here's the code I'm working on:

require 'dbi'

class Test
  def initialize
    @lims = DBI.connect("DBI:Mysql:lims", "myuser", "mypass")
  end

  def flatten(list)
    (!list) ? [] :
      ((list[0].type == Array) ? flatten(list[0]) : list[0].to_a) +
      flatten(list[1, list.length])
  end

  def get_client(abatno)
    @lims.prepare("select distinct SA_CLTNO from sample where SA_ABATNO =
                   '#{abatno}'") do |sth|
      sth.execute
      row   = sth.fetch_all
      rflat = row.flatten
      mflat = flatten(row)
      puts row.inspect
      puts rflat.inspect
      puts mflat.inspect
    end
  end
end

t = Test.new
t.get_client('54230')
# -------------------------
# output

[["213"], ["476"]] # row.inspect
[["213"], ["476"]] # rflat
["213", "476"]     # mflat

As you can see, the row.flatten method, isn't flattening the array. I'm quite
confused by this because if I go into irb and do:

[["213"], ["476"]].flatten

I get

["213", "476"]

Here's the result straight out of mysql, FYI.

mysql> select distinct SA_CLTNO from sample where SA_ABATNO = '54230';
+----------+
| SA_CLTNO |
+----------+
| 213      |
| 476      |
+----------+
2 rows in set (0.01 sec)

Any help would be appreciated.

-
Travis Whitton <whitton@atlantic.net>