From: Michael Libby <michael.c.libby@...>
Date: 2008-09-05T06:45:36+09:00
Subject: Re: How to save Ruby object as a blob in MySQL

On Thu, Sep 4, 2008 at 3:51 PM, Bryan Richardson <btrichardson@gmail.com> wrote:
> Hello all,
>
> I'm using Ruby and Sequel on Windows to talk to a database on a Linux
> machine.  The Sequel-to-MySQL connection is working fine -- I can save
> and query for data no problems.  However, I'm trying to save a Ruby
> object (an Array at this point) as a blob in the MySQL database and when
> I do I get some crazy stuff going on.  The code I am running is below:
>
> require 'rubygems'
> require 'sequel'
>
> DB = Sequel.connect 'mysql://test:test@172.16.234.1/sequel'
>
> DB.create_table :items do
>  column :name, :text
>  column :stuff, :blob
> end
>
> test = Array.new
> test << 145.0
> test << 231.56
>
> b = Marshal.dump(test)
>
> items = DB[:items]
> items << { :name => 'Test', :stuff => b }
>
> When I run this I get no errors at all.  However, when I move over to my
> Linux machine where the MySQL server is running and do a 'select * from
> items' query it looks like the blob data is overflowing out of the table
> and my command line gets all jacked up (see the attachment).  The
> command line stays jacked up even after I exit out of the mysql client
> console.
>
> Any ideas on why this is happening and more importantly how I can
> successfully marshal a Ruby object to my database?!

Are you sure it's not marshaling correctly? What happens when you
select that data back out and do Marshal::load ? The problem is more
likely your Linux terminal software following instructions you didn't
intend to give it.

If you examine the contents of b in your test code, you'll see some
pretty interesting values in there, and one of them is probably
messing up your display when you do your select statement in the mysql
client. This sort of thing happens all the time when dumping raw
binary data to a terminal. And while Marshal::dump returns a string,
it's really binary data.

irb(main):001:0> test = [145.0, 231.56]
=> [145.0, 231.56]
irb(main):002:0> b = Marshal.dump(test)
=> "\004\b[\af\b145f\016231.56\000\270R"

In most Linux terminals, you can use the 'reset' command to recover
when it gets garbled like this.

-Michael

>
> --
> Thanks!
> Bryan
>
> Attachments:
> http://www.ruby-forum.com/attachment/2649/ss.png
>
> --
> Posted via http://www.ruby-forum.com/.
>
>