Migrations :timestamp becomes :datetime in mySql


#1

For some reason whenever I try and create a timestamp column with
migrations and mysql I get a datetime column instead. That’s kind of
annoying because I want the column to update every time the row gets
changed. Is this a bug, or is there something I can do about it?
(Obviously I can manually change my mysql table, but that kind of
defeats the point of migrations!)

In my migration file:

create_table :some_table do |table|
     ...
     table.column :alter_date, :timestamp
     table.column :create_date, :datetime
end

But in mysql I get:

CREATE TABLE some_table (

alter_date datetime default NULL,
create_date datetime default NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci ;


#2

For some reason whenever I try and create a timestamp column with
migrations and mysql I get a datetime column instead. That’s kind of
annoying because I want the column to update every time the row gets
changed.

This is desired behaviour that allows for database neutrality (see
http://torch.cs.dal.ca/~ssmith/?p=41). If you rename the column to
updated_at rails will automagically do exactly what you want (see magic
field names: http://wiki.rubyonrails.com/rails/pages/MagicFieldNames).

Cheers Tom.


#3

I ran into this last week. It looks like a bug in mysql_adapter.rb.
Just changing line 106 to read:

:timestamp => { :name => “timestamp” },

may be enough to fix it, but I couldn’t be sure. Have a go.

-Jonathan.


#4

peter gd wrote:

For some reason whenever I try and create a timestamp column with
migrations and mysql I get a datetime column instead. That’s kind of
annoying because I want the column to update every time the row gets
changed. Is this a bug, or is there something I can do about it?

There was some reason for not supporting timestamp in migrations. This
is documented somewhere, perhaps just in a blog post. A little Googling
around ought to find it.

You can use the magic field names created_on/created_at and
updated_on/updated_at to get what you want. These fields are
automatically entered with the correct value whenever you create or
update a record.

http://api.rubyonrails.com/classes/ActiveRecord/Timestamp.html

Ray