Re: Syntax error, want to use multiple variables in one line, copy mysql data

On Mon, Dec 13, 2010 at 11:35 PM, K. V. <[e-mail]> wrote:
> I'm completely new to Ruby and trying to do something pretty simple --
> run through the lines of a database and copy them using ruby. The data's
> going from mysql to flockdb. The meat of the argument looks like this:
>
> res =3D mysql.query("SELECT source, target FROM old_data")
> while row =3D res.fetch_row do
> =C2=A0 =C2=A0 flock.add(row[0], :follows, row[1])
> =C2=A0 =C2=A0 end
>
> Now, I don't know what I'm doing wrong, though I'm sure it's easy, but
> this never works. If I use only one of the variables (either row[0] or
> row[1]) and make the other some constant (ie flock.add(1, :follows,
> row[1]) it works fine. But if I use two, it never works. Even if I want
> to check that they're integers,
>
> while row =3D res.fetch_row do
> =C2=A0 =C2=A0 Integer(row[0]), Integer(row[1])
> =C2=A0 =C2=A0 end
>
> it fails. I have checked separately and they are, so that's not the
> problem. These are the error messages that come back:
>
> NoMethodError: undefined method `<' for [0]:Array
> =C2=A0from
> /var/lib/gems/1.8/gems/thrift-0.2.0.4/lib/thrift/protocol/binary_protocol=
.rb:95:in
> `write_i64'
> =C2=A0from /var/lib/gems/1.8/gems/thrift-0.2.0.4/lib/thrift/client.rb:35:=
in
> `write'
> =C2=A0from /var/lib/gems/1.8/gems/thrift-0.2.0.4/lib/thrift/client.rb:35:=
in
> `send_message'
> =C2=A0from
> /var/lib/gems/1.8/gems/flockdb-0.5.1/lib/flock/gen-rb/flock_d_b.rb:102:in
> `send_execute'
> =C2=A0from
> /var/lib/gems/1.8/gems/flockdb-0.5.1/lib/flock/gen-rb/flock_d_b.rb:97:in
> `execute'
> =C2=A0from
> /var/lib/gems/1.8/gems/thrift_client-0.5.0/lib/thrift_client/abstract_thr=
ift_client.rb:115:in
> `send'
> =C2=A0from
> /var/lib/gems/1.8/gems/thrift_client-0.5.0/lib/thrift_client/abstract_thr=
ift_client.rb:115:in
> `handled_proxy'
> =C2=A0from
> /var/lib/gems/1.8/gems/thrift_client-0.5.0/lib/thrift_client/abstract_thr=
ift_client.rb:57:in
> `execute'
> =C2=A0from
> /var/lib/gems/1.8/gems/flockdb-0.5.1/lib/flock/operations/execute_operati=
ons.rb:13:in
> `apply'
> =C2=A0from /var/lib/gems/1.8/gems/flockdb-0.5.1/lib/flock/client.rb:77:in
> `update'
> =C2=A0from /var/lib/gems/1.8/gems/flockdb-0.5.1/lib/flock/client.rb:82:in
> `add'
> =C2=A0from (irb):41
> =C2=A0from /usr/lib/ruby/1.8/rubygems.rb:123
>
> What I don't get is why it will add them separately, but won't add both
> at the same time! Any help? All the tutorials seem to say this should
> work just fine, that multiple variables is not a problem. :(

Which library are you using to access the database (how did you
generate the mysql
variable) ?

One way that may be easier is to use the 'mysql2' gem.

  https://github.com/brianmario/mysql2#readme

I just tried a few things and it is really easy:

peterv@ASUS:~$ rvm use 1.9.2
Using /home/peterv/.rvm/gems/ruby-1.9.2-p0
peterv@ASUS:~$ gem install mysql2
Building native extensions.  This could take a while...
Successfully installed mysql2-0.2.6
1 gem installed
Installing ri documentation for mysql2-0.2.6...
Enclosing class/module 'mMysql2' for class Client not known
Enclosing class/module 'mMysql2' for class Result not known
Installing RDoc documentation for mysql2-0.2.6...
Enclosing class/module 'mMysql2' for class Client not known
Enclosing class/module 'mMysql2' for class Result not known
peterv@ASUS:~$ irb
ruby-1.9.2-p0 > require 'mysql2'
 =3D> true
ruby-1.9.2-p0 > client =3D Mysql2::Client.new(:host =3D> "localhost",
:username =3D> ".....", :password =3D> ".....", :database =3D>
"vandenabeele")
 =3D> #<Mysql2::Client:0x9aaff74>
ruby-1.9.2-p0 > results =3D client.query("SELECT * from people")
 =3D> #<Mysql2::Result:0x9aad558>
ruby-1.9.2-p0 > results.each do |row|
ruby-1.9.2-p0 >     puts row.inspect
ruby-1.9.2-p0 ?>  end.clear
{"id"=3D>1, "first_name"=3D>"Peter", "last_name"=3D>"Vandenabeele",
"birth_date"=3D>nil, "gsm_number"=3D>nil, "comment"=3D>nil,
"created_at"=3D>2010-10-06 22:20:00 +0200, "updated_at"=3D>2010-10-06
22:20:00 +0200}
 =3D> []
ruby-1.9.2-p0 > results =3D client.query("SELECT * from people")
 =3D> #<Mysql2::Result:0x9aebf38>
ruby-1.9.2-p0 > results.each do |row|
ruby-1.9.2-p0 >     puts "#{row['first_name']} #{row['last_name']}"
ruby-1.9.2-p0 ?>  end.clear
Peter Vandenabeele
 =3D> []

HTH,

Peter