# Mac OS X and Uninitialzed Constant Mysql

**URL:** <https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501>\
**Category:** Rails\
**Created:** [May 14, 2006, 11:21pm UTC](https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501 "2006-05-14T23:21:18Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/8baadc/32.png) [@jer](https://www.ruby-forum.com/u/jer)\
**Post date:** [May 14, 2006, 11:21pm UTC](https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501/1 "2006-05-14T23:21:18Z")

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Development Platform:  
ruby 1.8.4  
Rails 1.1.2  
mysql “gem” 2.7  
Mac OS X (10.4.6), 64-bit  
Mysql 5.0.19-standard (64-bit)  
Lighttpd, 1.4.11

I’m trying to startup a simple test rails app against mysql. Rails  
starts up fine and my pages render successfully, until a DB access is  
made. I’m getting a “uninitialized constant Mysql”. I’ve searched,  
but can’t find an answer. Thanks.

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<div class="post-metadata">

**Author:** ![jer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/8baadc/32.png) [@jer](https://www.ruby-forum.com/u/jer)\
**Post date:** [May 14, 2006, 11:32pm UTC](https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501/2 "2006-05-14T23:32:30Z")

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“uninitialized constant xxx” errors usually indicate that Ruby cannot  
find a definition for class xxx. Have you configured your databases  
correctly in config/database.yml ?

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<div class="post-metadata">

**Author:** ![jer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/8baadc/32.png) [@jer](https://www.ruby-forum.com/u/jer)\
**Post date:** [May 15, 2006, 4:24pm UTC](https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501/3 "2006-05-15T16:24:22Z")

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Try adding this to the top of your rb file:

require ‘mysql’

On 5/14/06, Mick S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> “uninitialized constant xxx” errors usually indicate that Ruby cannot  
> find a definition for class xxx. Have you configured your databases  
> correctly in config/database.yml ?
> 
> –  
> Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).
> 
> * * *
> 
> Rails mailing list  
> removed\_email\_address@domain.invalid  
> [http://lists.rubyonrails.org/mailman/listinfo/rails](http://lists.rubyonrails.org/mailman/listinfo/rails)

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<div class="post-metadata">

**Author:** ![jer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/8baadc/32.png) [@jer](https://www.ruby-forum.com/u/jer)\
**Post date:** [May 15, 2006, 10:36pm UTC](https://www.ruby-forum.com/t/mac-os-x-and-uninitialzed-constant-mysql/60501/4 "2006-05-15T22:36:26Z")

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Sounds like the mysql driver isn’t installed.

take a look at /config/database.yml :

# On MacOS X:

# gem install mysql – --include=/usr/local/lib

I used Todd Huss’s intel binary package for my macbook:

[Ruby on Rails Mac OS X Intel Binary | Todd Huss](http://gabrito.com/post/ruby-on-rails-mac-osx-intel-binary) (currently  
down)