Forum: Ruby on Rails Does ActiveRecord have support for "Boolean" columns?

Hey all --

I've been using enumerable char(1)'s with 'y' and 'n' values for my
Boolean columns in Rails, but it strikes me there should be a better
way.

How do you setup columns that represent true/false-ness in your
schemas on Rails?

Wondering what kind of standard approaches there are other than me
writing something like

class MyEntity < ActiveRecord::Base
  def active
     return false unless active=='y'
     true
  end
end

-- Brendan Baldwin (dot com)

> I've been using enumerable char(1)'s with 'y' and 'n' values for my
> Boolean columns in Rails, but it strikes me there should be a better
> way.

Just sharing, cuz I haven't found a better way than yours -- I use 
tinyints, set after my migration has run, of course...

If you use migrations to create your database, you can specify boolean
columns:

class CreateUsers < ActiveRecord::Migration
  def self.up
    create_table :users do |table|
      table.column :username, :string, :limit => 32, :null => false
      table.column :active, :boolean
    end
  end

  def self.down
    drop_table :users
  end
end

using MySQL for the DB, it creates a TINYINT(1) column, in which is 
stores 0
or 1.  ActiveRecord then treats it as a boolean.

> using MySQL for the DB, it creates a TINYINT(1) column, in which is 
> stores 0
> or 1.  ActiveRecord then treats it as a boolean.

Well, how ace is that?
Excuse me -- I have some migrations editing to do...
Cheers, man!

Rails treats an integer field with 0 and 1 as a boolean. The 
checkbox_field helpers know what to do with 0 and 1 values, and scaffold 
generators create pulldowns for those fields with "True" and "False" on 
the labels and 0 and 1 as the return values.

If you use migrations to maintain your database schema, a command like

    add_column :salespeople, :has_been_trained, :boolean, :default => 
false

will create the appropriate field type for you. On MySQL this generates 
a tinyint(1) in the salespeople table, with a default of 0.

Brendan Baldwin wrote:
> Hey all --
> 
> I've been using enumerable char(1)'s with 'y' and 'n' values for my
> Boolean columns in Rails, but it strikes me there should be a better
> way.
> 
> How do you setup columns that represent true/false-ness in your
> schemas on Rails?
> 
> Wondering what kind of standard approaches there are other than me
> writing something like
> 
> class MyEntity < ActiveRecord::Base
>   def active
>      return false unless active=='y'
>      true
>   end
> end
> 
> -- Brendan Baldwin (dot com)

I generated my models from postgresql tables with booleans in them. 
They
seem to work fine without any extra effort.

Each of the database adapters is responsible for determining how to
handle a boolean column in a way that makes sense for their specific
backend.  In the case of PostgreSQL and OpenBase this is trivial,
since these database backends have a boolean type column built-in.
For MySQL - as has been pointed out - booleans are usually handled as
tinyint.  The MySQL adapter therefore will default to handle tinyint
columns as booleans.  However, this behavior can be changed by
setting MysqlAdapter.emulate_booleans = false.

If you define your schema within rails and give the column a type
of :boolean, then the adapter you are using will create a column of
whatever type makes sense for that database, thus achieving (at least
to this extent) database agnosticism.  Beautiful.  Sorta brings a
tear to your eye, doesn't it?

-Derrick Spell

Thats great news about MySQL and TinyInt :-)  I didn't realize that one.

Thanks for the replies everyone!  I think I'm going to start exploring
Migrations now.

--Brendan

I don't think this was mentioned yet. You can place a question mark
after the getter method to inform ActiveRecord that you expect the
attribute to be a boolean. For example:

entity = MyEntity.find(:first)
if entity.active?
   # do something
end

This is good for a couple reasons:

1. It follows the ruby standard of placing a question mark after a
method which returns a boolean.
2. It converts the column value into a boolean. Example: '0', 'f',
'false', and '' (empty string) all return false. Everything else
returns true. Unfortunately, it doesn't recognize "n" as false.

Hope that helps.

Ryan

On Apr 7, 2006, at 1:29, Ryan Bates wrote:

> I don't think this was mentioned yet. You can place a question mark  
> after the getter method to inform ActiveRecord that you expect the  
> attribute to be a boolean. For example:
>
> entity = MyEntity.find(:first)
> if entity.active?
>   # do something
> end

In addition you can use booleans in find_bys:

    entity = MyEntity.find_all_by_active(true) # no SQL here

Since that's a little tricky I try to avoid hard-coding any boolean-
like literal as one would do with :conditions.

-- fxn