MySQL Gem failure: MysqlCompat::MysqlRes on Snow Leopard

Question

I am trying to get the mysql gem to work ... and it just doesn't want to. Every time I do a rake db:migrate, I get

uninitialized constant MysqlCompat::MysqlRes

I've installed mysql from this disk image: mysql-5.5.9-osx10.6-x86_64.dmg

I've run the gem install with the infamous archflags setting:

sudo env ARCHFLAGS="-arch x86_64" gem install --no-rdoc --no-ri mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

And the ruby version I'm using is the default from Snow Leopard:

[~/sites/testdb]$ file `which mysql`
/usr/local/mysql/bin/mysql: Mach-O 64-bit executable x86_64
[~/sites/testdb]$ file `which ruby`
/usr/bin/ruby: Mach-O universal binary with 3 architectures
/usr/bin/ruby (for architecture x86_64):    Mach-O 64-bit executable x86_64
/usr/bin/ruby (for architecture i386):  Mach-O executable i386
/usr/bin/ruby (for architecture ppc7400):   Mach-O executable ppc

My database.yml is pretty simple:

development:
  adapter: mysql
  host: 127.0.0.1
  database: testdb
  username: root
  password: 

Any help would be appreciated.

Answer 1

You can easy fix your problem.

If you don't use rvm:

sudo install_name_tool -change libmysqlclient.16.dylib /usr/local/mysql/lib/libmysqlclient.16.dylib /Library/Ruby/Gems/1.8/gems/mysql-2.8.1/lib/mysql_api.bundleruby

If you use rvm:

install_name_tool -change libmysqlclient.16.dylib usr/local/mysql/lib/libmysqlclient.16.dylib [YOUR_GEMSET_PATH]/gems/mysql-2.8.1/lib/mysql_api.bundle

Answer 2

I blogged about this last week: MySQL 5.5 on Mac OS X .

My alternate solution to using install_name_tool is to set DYLD_LIBRARY_PATH in your shell startup files. The advantage to this you do it once, whereas if you use install_name_tool , you will repeat that every time to re-install or upgrade the gem.

The mysql2 gem will have the same problem with a slightly different error message. The problem is how the libmysqlclient library is built. It doesn't include a full path, so anything linking with it can't find it at runtime.

Answer 3

You could try using the mysql2 gem which may not suffer from the same problems.

I've found it's often a lot better to use ruby and mysql from MacPorts or brew to keep everything on the same page and not mess with the system Ruby.

OS X comes with a version of MySQL that may not match up with what you have installed, or perhaps the gem installer is confused about which config program to use. Make sure mysql_config is returning the correct path.

Answer 4

I ran into the same error. On my machine, though, the mysql gen was built when I still had mysql 5.1 on my machine. Now, after upgrading to MySQL 5.5, the dyld-file referred by the original build /usr/local/mysql/lib/libmysqlclient.16.dylib didn't exist any more and was replaced by a file /usr/local/mysql/lib/libmysqlclient.18.dylib .

Completely rebuilding the mysql gem fixed things, ie

gem uninstall mysql
gem install mysql