Auto-increment lost during migration

Rails
1

Hi. I get some strange results when using rename_column on a primary
key in a migration. It seems like the migration script removes the
auto-increment property if you rename a column.

This is a minimal example.

create_table :foo, :primary_key => :foo_id do |t|
  t.column "name", :string
end

# renaming the primary key makes auto-increment disappear.
rename_column :foo, :foo_id, :bar_id

Is this a known problem, any beautiful solution available? Maybe use
change_column instead?

Best regards,
Tobias Nurmiranta

2

Tobias Numiranta wrote:

create_table :foo, :primary_key => :foo_id do |t|
  t.column "name", :string
end

# renaming the primary key makes auto-increment disappear.
rename_column :foo, :foo_id, :bar_id

What RDBMS are you using? Can you show what the table schema looks like
(as reported by the rdbms) before and after the change?

3

Sure. I’m using Mysql. Using mysqldump before and after I get:

before:

CREATE TABLE foo (
foo_id int(11) NOT NULL auto_increment,
name varchar(255) default NULL,
PRIMARY KEY (foo_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

after:

CREATE TABLE foo (
bar_id int(11) NOT NULL default ‘0’,
name varchar(255) default NULL,
PRIMARY KEY (bar_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Have a nice day,
T

4

Tobias Numiranta wrote:

after:

CREATE TABLE foo (
bar_id int(11) NOT NULL default ‘0’,
name varchar(255) default NULL,
PRIMARY KEY (bar_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Interesting. I don’t use MySQL. What do the logs show as the SQL being
issued to MySQL for the change_column migration?

5

On Oct 31, 6:14 pm, “Phrogz” [email protected] wrote:

after:

CREATE TABLE foo (
bar_id int(11) NOT NULL default ‘0’,
name varchar(255) default NULL,
PRIMARY KEY (bar_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;Interesting. I don’t use MySQL. What do the logs show as the SQL being
issued to MySQL for the change_column migration?

Hi. This is the issued SQL:

– create_table(:foo, {:primary_key=>:foo_id})
CREATE TABLE foo (foo_id int(11) DEFAULT NULL auto_increment PRIMARY
KEY, name varchar(255)) ENGINE=InnoDB

– rename_column(:foo, :foo_id, :bar_id)
SHOW COLUMNS FROM foo LIKE ‘foo_id’
ALTER TABLE foo CHANGE foo_id bar_id int(11)

Maybe the alter table command need to specify auto_increment, but rails
doesn’t do so?