Add timestamps to an existing table

Question

I need to add timestamps (created_at & updated_at) to an existing table. I tried the following code but it didn\'t work.

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Answer 1

I'm on rails 5.0 and none of these options worked.

The only thing that worked was using the type to be :timestamp and not :datetime

def change
    add_column :users, :created_at, :timestamp
    add_column :users, :updated_at, :timestamp
end

Answer 2

Migrations are just two class methods (or instance methods in 3.1): up and down (and sometimes a change instance method in 3.1). You want your changes to go into the up method:

class AddTimestampsToUser < ActiveRecord::Migration
  def self.up # Or `def up` in 3.1
    change_table :users do |t|
      t.timestamps
    end
  end
  def self.down # Or `def down` in 3.1
    remove_column :users, :created_at
    remove_column :users, :updated_at
  end
end

If you're in 3.1 then you could also use change (thanks Dave):

class AddTimestampsToUser < ActiveRecord::Migration
  def change
    change_table(:users) { |t| t.timestamps }
  end
end

Perhaps you're confusing def change, def change_table, and change_table.

See the migration guide for further details.

Answer 3

This is a simple one to add timestamp in existing table.

class AddTimeStampToCustomFieldMeatadata < ActiveRecord::Migration
  def change
    add_timestamps :custom_field_metadata
  end
end

Answer 4

This seems like a clean solution in Rails 5.0.7 (discovered the change_column_null method):

def change
  add_timestamps :candidate_offices, default: nil, null: true
  change_column_null(:candidate_offices, :created_at, false, Time.zone.now)
  change_column_null(:candidate_offices, :created_at, false, Time.zone.now)
end

Answer 5

not sure when exactly this was introduced, but in rails 5.2.1 you can do this:

class AddTimestampsToMyTable < ActiveRecord::Migration[5.2]
  def change
    add_timestamps :my_table
  end
end

for more see "using the change method" in the active record migrations docs.

Answer 6

Your original code is very close to right, you just need to use a different method name. If you're using Rails 3.1 or later, you need to define a change method instead of change_table:

class AddTimestampsToUser < ActiveRecord::Migration
  def change
    add_timestamps(:users)
  end
end

If you're using an older version you need to define up and down methods instead of change_table:

class AddTimestampsToUser < ActiveRecord::Migration
  def up
    add_timestamps(:users)
  end

  def down
    remove_timestamps(:users)
  end
end