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MySQL and Ruby on Rails datatypes

Posted 29 June, 2007 at 12:36pm by Michael Chu
(Filed under: Ruby on Rails, Web 2.0)

One of the best features of Ruby on Rails is the ability to interact with database tables as objects using ActiveRecord. Sometimes documentation can be a bit spotty, but after searching for a little bit it's not hard to find the mapping from Rails Migration types to MySQL data types. I did find it more difficult to find out what happens if I already have an existing MySQL table. What Ruby class gets created with what MySQL column type? I didn't find it on the web, so I put together this list…

I added links to MySQL documentation for each of the MySql data types and links to the relevant Ruby class type to make this table a bit more useful.
MySQL Column Data Type to Ruby class type (when using ActiveRecord)

MySQL Data Type Empty Ruby Class Ruby Class
bigint NilClass Bignum
binary String String
blob String String
bool NilClass TrueClass
FalseClass
char String String
date NilClass Date
datetime NilClass Time
decimal NilClass Fixnum
double NilClass Float
enum String String
float NilClass Float
int NilClass Bignum
longblob String String
longtext String String
mediumblob String String
mediumint NilClass Fixnum
mediumtext String String
set NilClass String
smallint NilClass Fixnum
text String String
time NilClass Time
timestamp NilClass Time
tinyblob String String
tinyint NilClass Fixnum
tinyint(1) NilClass TrueClass
FalseClass
tinytext String String
varbinary String String
varchar String String
year NilClass String

For completeness sake, here's a summary of Rails migration types and their MySQL column data types.
Rails Migration Type to MySQL Column Data Type

Rails Migration Symbol MySQL Data Type
:binary blob
:boolean tinyint(1)
:date date
:datetime datetime
:decimal decimal
:float float
:integer int(11)
:string varchar(255)
:text text
:time time
:timestamp datetime

11 comments to MySQL and Ruby on Rails datatypes

Free as in Time » Blog Archive » RoR Tuesday 03/07/2007, July 11th, 2007 at 8:37 am:

  • […] MySQL and Ruby on Rails datatypes - Sweet resource. One of the best features of Ruby on Rails is the ability to interact with database tables as objects using ActiveRecord. Sometimes documentation can be a bit spotty, but after searching for a little bit it’s not hard to find the mapping from Rails Migration types to MySQL data types. I did find it more difficult to find out what happens if I already have an existing MySQL table. What Ruby class gets created with what MySQL column type? I didn’t find it on the web, so I put together this list… […]

viktor, August 30th, 2007 at 4:28 am:

  • This is nice, but it seems like a flaw that Ruby on rails is incapable of managing the "double" data type..

    I know that there is a patch avaliable: http://dev.rubyonrails.org/ticket/7594 .
    Will that ever be a part of the standard RoR package ?

Tipos de datos Ruby on Rails a MySQL « Leobrambilla Weblog, August 30th, 2007 at 1:31 pm:

  • […] Esta es una info que me costo un poco encontrar por eso la comparto. Son los datos a cargar en el Modelo generado por […]

links for 2008-03-24 « Web Flakes, March 23rd, 2008 at 8:17 pm:

  • […] MySQL and Ruby on Rails datatypes (tags: rails.datatypes) […]

digital subterfuge » Blog Archive » Apples and Oranges. Er, RoR and MySQL data types., May 12th, 2008 at 10:09 pm:

  • […] This site has a handy chart to tell you. […]

Anonymous, March 17th, 2009 at 7:57 am:

  • good job!

Migrar una base de datos localizada con Ruby on Rails « Constructor sobrecargado, August 30th, 2009 at 2:04 am:

  • […] MySQL and Ruby on Rails datatypes […]

TNT, October 25th, 2009 at 5:35 am:

  • VERY IMPORTANT FOR CURRENCIES AND SIMILIAR:

    The decimal type is only mapped to Fixnum if :scale => 0 (which is the default). But if :scale is > 0 decimal is mapped to BigDecimal which is what we need for computations without the Float rounding errors.

Flex For Rails Scaffold | Softarama Labs, October 11th, 2010 at 3:27 pm:

  • […] (data types with Ruby and mySQL) […]

Visoft, Inc. Blogs | Rails 101 – Rails 01, April 24th, 2011 at 7:50 am:

  • […] http://www.orthogonalthought.com/blog/index.php/2007/06/mysql-and-ruby-on-rails-datatypes/ This entry was posted in Uncategorized. Bookmark the permalink. Post a comment or leave a trackback: Trackback URL. Damien White is a developer in Connecticut that simply loves coding. Ever since he was young, he has had a driving passion for computers and software development, and a thirst for knowledge that just cannot be quenched. He’s happy to share what he knows in his quest to learn as much as possible. « Entity Framework – Removing Foreign Keys from the Entity Model […]

Rails – Tipos de dados do ActiveRecord « RacionalRubyRails, May 19th, 2011 at 6:05 am:

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