Ruby Rails - 使用created_at列创建表

Ruby on rails has the t.timestamps method which creates two columns, created_at and updated_at. How can I make just the created_at column?

Ruby on rails具有t.timestamps方法,该方法创建两列,created_at和updated_at。我怎样才能创建created_at列?

This works

class CreateLinesSources < ActiveRecord::Migration
  def change
    create_table :lines_sources do |t|
      t.timestamps null: false
    end
  end
end

Both of these I want to work but fail

这两个我想工作但失败了

class CreateLinesSources < ActiveRecord::Migration
  def change
    create_table :lines_sources do |t|
      t.created_at null: false
    end
  end
end

and

class CreateLinesSources < ActiveRecord::Migration
  def change
    create_table :lines_sources do |t|
      t.timestamps null: false
      remove_column updated_at
    end
  end
end

3 个解决方案

#1

Both attempts are okay but contains syntax error.

两次尝试都没问题,但包含语法错误。

The problem on the first attempt is that the t. is on datatype not column name.

第一次尝试的问题是t。是基于数据类型而不是列名。

class CreateLinesSources < ActiveRecord::Migration
  def change
    create_table :lines_sources do |t|
      t.datetime :created_at, null: false
    end
  end
end

The problem on the second attempt is that remove_column does not work inside create_table block. You can move it outside the block and provide correct syntax to remove the column.

第二次尝试的问题是remove_column在create_table块中不起作用。您可以将其移出块外,并提供正确的语法来删除列。

class CreateLinesSources < ActiveRecord::Migration
  def change
    create_table :lines_sources do |t|
      t.timestamps null: false
    end
    remove_column :line_sources, :updated_at, :datetime
  end
end

#2

t.datetime :created_at, null: false

Just like any other column. Rails will still take care of magic updating because of column name.

就像任何其他专栏一样。由于列名,Rails仍然会处理魔术更新。

#3

You can do:

你可以做:

def change
  create_table :lines_sources do |t|
    t.datetime :created_at, null: false
  end
end

#1