I created a new migration, where is mentioned
... t.timestamps
in the created table are added these two columns
... | created_at | datetime | NO (Null) | | NULL (Default) | | updated_at | datetime | NO (Null) | | NULL (Default) | ...
When I want to create a new item, I always get the error message
Mysql2::Error: Field 'created_at' doesn't have a default value: INSERT INTO `table_name` (`first_col`, `second_col`) VALUES ('a', 'b')
Am I missing something? I sent this miniapp to a friend of mine and he is able to run successfully run it -> the record is created in database.
What am I missing?
I just ran into something similar on a fresh install of MySql on Mac OS.
I finally narrowed it down to the combination of newer versions of MySql turning on "strict mode" by default, and my project having a table with some questionable constraints on it. The table in question was the "join table" used in a :has_and_belongs_to_many relationship. Somehow that table had been created with :created_at, and :updated_at attributes that had a constraint of :null => false on them. Rails 3.2 doesn't automatically populate the timestamp fields for join tables of :habtm relationships. When strict mode is turned off MySql will just populate the cols with zeroed out dates, like 0000-00-00 00:00:00. With strict mode turned on it raises an exception.
To fix the issue I ran a migration to allow the timestamp fields to be null. Like this:
class ChangeNullableForTimestampsOnThing1sThing2s < ActiveRecord::Migration def up change_column(:thing1s_thing2s, :created_at, :datetime, :null => true) change_column(:thing1s_thing2s, :updated_at, :datetime, :null => true) end def down change_column(:thing1s_thing2s, :created_at, :datetime, :null => false) change_column(:thing1s_thing2s, :updated_at, :datetime, :null => false) end end
Honestly, it's probably better to just drop the columns if you don't need them, but we have a couple of special cases where they actually get set manually.
to add to Jeremy's answer, on a mac you can remove strict mode with
> vi /usr/local/opt/mysql/my.cnf
then replace
sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
with
sql-mode="NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
