Installing the MySQL gem on OS X

If you manage your system packages via the MacPorts system you may run into some problems when trying to install the native MySQL driver gem on OS X.

Typically, you'd see output like this when trying to install the gem:

$ sudo gem install mysql
Building native extensions.  This could take a while...
ERROR:  Error installing mysql:
        ERROR: Failed to build gem native extension.

/opt/local/bin/ruby extconf.rb
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/opt/local/bin/ruby
        --with-mysql-config
        --without-mysql-config
        --with-mysql-dir
        --without-mysql-dir
        --with-mysql-include
        --without-mysql-include=${mysql-dir}/include
        --with-mysql-lib
        --without-mysql-lib=${mysql-dir}/lib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-mlib
        --without-mlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-zlib
        --without-zlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-socketlib
        --without-socketlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-nsllib
        --without-nsllib
        --with-mysqlclientlib
        --without-mysqlclientlib


Gem files will remain installed in /opt/local/lib/ruby/gems/1.8/gems/mysql-2.7 for inspection.
Results logged to /opt/local/lib/ruby/gems/1.8/gems/mysql-2.7/gem_make.out

Based on those errors the configure process seems to be failing when looking for MySQL libs. The default path to the libs based on extconf.rb seems to be /usr/local which is not where the ports system installs MySQL.

All you need to do is point to the correct mysql_config and let the gem install command line know of this to get things going:

$ sudo gem install mysql -- --with-mysql-config=/opt/local/bin/mysql_config5  
Building native extensions.  This could take a while...
Successfully installed mysql-2.7
1 gem installed

All's well that ends well.

Links

IRB
Dr Nic has a great little article describing his favourite additions to his .irbrc. He covers some common productivity wins such as:

• TABed auto-completion
• Map by method which allows you to get rid of constructs like articles.columns.map {|p| p.name} or articles.columns.map &:name and simply replace it with a plural: articles.columns.names or articles.columns.name
• MethodFinder/Object.what?
• pp
• Auto-tabbing

GuessMethod
This little gem is the best bad idea ever! Gone are those frustrating typos that waste extra cycles finding and fixing them.

Wirble
Continuing on the irb enhancements theme do yourself a favour and have a look at Wirble. It offers you tab-completion, history, and a built-in ri command as well as colorised results and a couple other goodies.