From: Robert Klemme <shortcutter@...>
Date: 2010-12-14T18:11:26+09:00
Subject: 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. <kvaccaro@mitre.org> 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 = mysql.query("SELECT source, target FROM old_data")
> while row = res.fetch_row do
>     flock.add(row[0], :follows, row[1])
>     end

Maybe row looks different than you think.  I would try this

require 'pp'
...
while row = res.fetch_row do
  pp row
  flock.add(row[0], :follows, row[1])
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 = res.fetch_row do
>     Integer(row[0]), Integer(row[1])
>     end
>
> it fails. I have checked separately and they are, so that's not the
> problem. These are the error messages that come back:

This cannot work:

09:32:36 ~$ ruby19 -c <<CODE
> while row = res.fetch_row do
>     Integer(row[0]), Integer(row[1])
>     end
> CODE
-:2: syntax error, unexpected ',', expecting keyword_end
    Integer(row[0]), Integer(row[1])
                    ^
09:32:46 ~$

This is the error condensed to the simplest case:

09:32:46 ~$ ruby19 -ce 'a'
Syntax OK
09:33:24 ~$ ruby19 -ce 'a,b'
-e:1: syntax error, unexpected '\n', expecting '='
09:33:27 ~$

You cannot have two expressions separated with comma - unless it's a
list of arguments for a method call.

> NoMethodError: undefined method `<' for [0]:Array
>  from

Probably the code expects a number and not an Array.  Whether that's a
bug in your code or in any of the used gems I cannot really tell ATM.

> 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. :(

Maybe that information is not in sync with the version of the software
you have.  Maybe authors of these gems can help.

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/