From: niklas | brueckenschlaeger <niklas@...>
Date: 2010-11-15T17:53:07+09:00
Subject: Re: Mysql::Result .each_hash - unexpected result

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This is a mysql specific problem, not ruby. Result#each_hash is just
syntactic sugar for Result#fetch_hash:

  while tag =3D tags.fetch_hash
  end
  # is the same as:
  tags.each_hash do |tag|
  end

Internally each_hash uses fetch_hash as well:
http://rdoc.info/github/luislavena/mysql-gem/master/Mysql/Result#each_hash-=
instance_method

One way of solving this would be to keep the results you want to re-use
within an array:

  require "mysql"
  db =3D Mysql.connect('localhost', 'root', '', 'test')

  items =3D db.query('SELECT * FROM items')
  tag_result =3D db.query('SELECT * FROM tags')
  tags =3D []
  tag_result.each_hash { |t| tags << t }

  items.each_hash do |item|
     puts item["title"]
     tags.each do |tag|
        puts tag["name"]
     end
  end

  puts tag_result.num_rows
  puts items.num_rows

Hope this helps.

On Mon, 2010-11-15 at 03:36 +0900, Andy Tolle wrote:
> botp wrote in post #961345:
> > On Sun, Nov 14, 2010 at 5:55 PM, Andy Tolle <durexlw.register@gmail.com=
>
> > wrote:
> >> items.each_hash do |item|
> >>  puts item["title"]
> >>  tags.each_hash do |tag|
> >
> > at this point, i'd be wary.  the iterator may not "rewind"
>=20
> Can you say something about how an iterator can not "rewind"? Do you=20
> mean I can't do nested iterators in ruby?
>=20


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