How to create a column of type tinyint(2) or tinyint(3) in Ruby on Rails?

Question

In Ruby on Rails, the following code in a migration creates a column of type tinyint(4) in MySQL:

create_table :great_table do |t|
    t.integer :step_position, :limit => 1 #tinyint
end

How would I create a column of type tinyint(2) or tinyint(3)?

Answer 1

For tinyint(2)

create_table :great_table do |t|
  t.integer :step_position, :limit => 2
end

For tinyint(3)

create_table :great_table do |t|
  t.integer :step_position, :limit => 3
end

Answer 2

According to what I can see in the source code of the gem, you can't:

     # File activerecord/lib/active_record/connection_adapters/mysql_adapter.rb, line   540  
     540:       def type_to_sql(type, limit = nil, precision = nil, scale = nil)
     541:         return super unless type.to_s == 'integer'
     542: 
     543:         case limit
     544:         when 1; 'tinyint'
     545:         when 2; 'smallint'
     546:         when 3; 'mediumint'
     547:         when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
     548:         when 5..8; 'bigint'
     549:         else raise(ActiveRecordError, "No integer type has byte size #{limit}")
     550:         end
     551:       end

type_to_sql

Answer 3

There is no such thing as tinyint(4) in MySQL in the first place. tinyint is a one byte signed integer. You can check all integer types in the docs. You may see something like tinyint(1) even in the Rails source code, but I think it's a tautology as tinyint already implies one byte storage.

The Rails way to declare TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT in a migration is by using limit: with the appropriate byte size as can be seen in the source code.

Beware that Rails will treat one-byte integers as booleans by default though, as can be seen from the above link.

Answer 4

You can use :tinyint as the column type in a rails migration, and write limit: 2 or limit: 3 as written before.

Using your example:

create_table :great_table do |t|
    t.tinyint :step_position, :limit => 1
end

should work.