# Help with mysql\_adapter.rb?

**URL:** <https://www.ruby-forum.com/t/help-with-mysql-adapter-rb/54747>\
**Category:** Rails\
**Created:** [March 13, 2006, 11:19pm UTC](https://www.ruby-forum.com/t/help-with-mysql-adapter-rb/54747 "2006-03-13T23:19:32Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![drsharp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/e9bcb4/32.png) [@drsharp](https://www.ruby-forum.com/u/drsharp)\
**Post date:** [March 13, 2006, 11:19pm UTC](https://www.ruby-forum.com/t/help-with-mysql-adapter-rb/54747/1 "2006-03-13T23:19:32Z")

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Hello all! I’m a newbie to Rails and I’m trying to get things working on  
an old RH9 box. I was wondering if someone could help me troubleshoot a  
mysql\_adapter.rb error?

I set everything up and created a simple test app and then generated a  
scaffold for it. When I try to go to the main controller and list the  
data, I get the following error:

ArgumentError…  
NULL pointer given

The stack trace starts in my controller where it is trying to return the  
values for the “list” action (simply read the records in the DB), but  
the actual error appears to be in mysql\_adapter.rb:326 as part of the  
private “select” method.

I don’t know if the problem is in this adapter or has to do with my  
configuration. Is there a way to set debug statements in code that’s  
not part of your app? I’d like to see what the “sql” variable is in the  
“select” method of mysql\_adapter.rb to try and see what’s going on.

Lessee… I am using MySQL 4.1 with a user account without a password.  
I’m running the latest stable ruby and rails packages (installed today).  
I’ve tried both webrick and lighttpd and neither matters. I also had  
this error when I had MySQL 4.0 installed earlier today (I upgraded as  
part of my attempts to figure this out). As near as I can tell,  
everything else is working. The irony is that the default controller  
when the DB table is empty works and shows the form… and lets me  
insert. So INSERT commands are working, but then the view to show the  
list chokes. Why would INSERT work but not SELECT?? Hrm.

Anyway, I’d love any help with this… even as simple as how to debug  
the Ruby code in mysql\_adapter.rb to determine what values are getting  
passed in/out.

BTW, I don’t know if there is a better place to post these questions.  
I’ve been banging my head against this all day. If it would be better to  
contact me directly instead of via the list, please do so. 🙂  
removed\_email\_address@domain.invalid

Thanks!

-Dan

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<div class="post-metadata">

**Author:** ![drsharp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/e9bcb4/32.png) [@drsharp](https://www.ruby-forum.com/u/drsharp)\
**Post date:** [March 14, 2006, 11:13am UTC](https://www.ruby-forum.com/t/help-with-mysql-adapter-rb/54747/2 "2006-03-14T11:13:18Z")

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Hello,

Try ‘gem install mysql’

For installing base ruby adapter dependency.

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<div class="post-metadata">

**Author:** ![drsharp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/e9bcb4/32.png) [@drsharp](https://www.ruby-forum.com/u/drsharp)\
**Post date:** [March 14, 2006, 7:37pm UTC](https://www.ruby-forum.com/t/help-with-mysql-adapter-rb/54747/3 "2006-03-14T19:37:31Z")

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Mathieu C. wrote:

> Hello,
> 
> Try ‘gem install mysql’
> 
> For installing base ruby adapter dependency.

Mathieu,

Thanks. I tried this but it didn’t make any difference. The mysql  
adapter is already there and installed (as I said, INSERT calls go  
through).

In trying to narrow this down, I’ve set up Rails & MySQL on my windoze  
box as well. I then did a super-simple test case on both windows and  
linux. The windows version worked fine, the linux version crashed with  
the same null pointer error.

I then tried to run the windows version (i.e code & server on windows)  
but connecting to the linux database (via TCP/IP sockets). That worked  
fine.

I then tried to run the linux version (i.e. code & server on linux) but  
connecting to the linux database via TCP/IP instead of mysql.sock. That  
crashed (same null pointer error).

I couldn’t get it to work where the code & server on linux connects to  
the windows database (some mysql connection issue… probably a  
misconfiguration or something).

So it seems that I’ve narrowed it down to most likely a mysql.sock  
error. I wish I knew how to further troubleshoot it.

But at least I can get back into Rails development (yippee!)

Anyway… I imagine a clean install of mysql might help, but I’ve got  
lots of legacy databases that I’d hate to lose. Hrm. So if anyone has  
any other thoughts or suggestions, I’d be open to them. 🙂

Thanks!

-Dan