是什么决定了rails是否在表定义中包含id：：serial？ [英] What determines if rails includes id: :serial in a table definition?

问题描述

我正在使用postgresql使用现有的Rails应用程序。对于许多（但不是全部）表，其schema.rb文件具有 id：：serial ：

I'm working with an existing rails app, using postgresql. Its schema.rb file has id: :serial for many, but not all, tables:

create_table "foos", id: :serial, force: :cascade do |t|

当我运行 rails db：migrate：reset ， id：：serial 被删除。我们都使用相同版本的postgres，但使用不同的操作系统。我尚未详尽测试机器之间的行为，但我认为机器之间存在差异。

When I run rails db:migrate:reset, id: :serial is removed. We are all on the same version of postgres, but different OSes. I haven't exhaustively tested the behavior between machines, but I think there is a difference between machines.

rails版本与项目开始时的版本相同。

The rails version is the same as it was when the project started.

该项目确实从sqlite3开始。当我切换到该文件并重新生成文件时，行为相同。

The project did start with sqlite3. When I switch to that and regenerate the file, same behavior.

什么会导致在我的环境中删除此选项？

What could cause this option to be removed in my environment?

下面是一些可能相关的代码：

here's some code that is probably relevant:

• https://github.com/rails/rails/blob/b2eb1d1c55e59 active_record / connection_adapters / postgresql / column.rb＃L15-L21


• https://github.com/rails/rails/blob/b2eb1d1c55a59fee1e6c4cba7030d8ceb524267c/activerecord/lib/active_record/poster_umper .rb＃L26-L42

• https://github.com/rails/rails/blob/b2eb1d1c55a59fee1e6c4cba7030d8ceb524267c/activerecord/lib/active_record/connection_adapters/postgresql/column.rb#L15-L21
• https://github.com/rails/rails/blob/b2eb1d1c55a59fee1e6c4cba7030d8ceb524267c/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb#L26-L42

更新

• 我刚刚在同事的机器上尝试了 rails db：migrate：reset ，我错了！他们的环境还删除了 id :: serial 。


• 我仔细查看了最近从一位同事处进行的迁移，但最近一次没有要么在schema.rb中创建 id :: serial 。

• I just tried rails db:migrate:reset on colleague's machines, and I was wrong! their environments also remove id: :serial.
• I looked closer at recent migrations from a colleague, and the most recent one did not create id: :serial in schema.rb either.

推荐答案

答案仅是Rails 5.0与5.1迁移。我以前曾以为该项目始于5.1，所以我没有对此进行测试。但是后来我更深入地研究，发现它始于5.0，实验表明这就是答案。

The answer is simply rails 5.0 vs 5.1 migrations. I had previously thought that the project started in 5.1, so I didin't test this. But then I dug deeper and discovered it started in 5.0, and experimentation shows that's the answer.

class SerialIdTest < ActiveRecord::Migration[5.0]
  def change
    create_table "test" do |t|
      t.integer "foo_id"
      t.string "foo_role"
    end
  end
end

create_table "test", id: :serial, force: :cascade do |t|
  t.integer "foo_id"
  t.string "foo_role"
end

# \d test
                                   Table "public.test"
      Column      |       Type        |                       Modifiers                       
------------------+-------------------+-------------------------------------------------------
 id               | integer           | not null default nextval('test_id_seq'::regclass)
 foo_id   | integer           | 
 foo_role | character varying | 
Indexes:
    "test_pkey" PRIMARY KEY, btree (id)

5.1 ，未指定ID

5.1, no id specified

class SerialIdTest < ActiveRecord::Migration[5.1]
  def change
    create_table "test" do |t|
      t.integer "foo_id"
      t.string "foo_role"
    end
  end
end

create_table "test", force: :cascade do |t|
  t.integer "foo_id"
  t.string "foo_role"
end

# \d test
                                   Table "public.test"
      Column      |       Type        |                       Modifiers                       
------------------+-------------------+-------------------------------------------------------
 id               | bigint            | not null default nextval('test_id_seq'::regclass)
 foo_id   | integer           | 
 foo_role | character varying | 
Indexes:
    "test_pkey" PRIMARY KEY, btree (id)

5.1 ，指定的ID序列

5.1, id serial specified

class SerialIdTest < ActiveRecord::Migration[5.1]
  def change
    create_table "test", id: :serial do |t|
      t.integer "foo_id"
      t.string "foo_role"
    end
  end
end

create_table "test", id: :serial, force: :cascade do |t|
  t.integer "foo_id"
  t.string "foo_role"
end

# \d test
                                   Table "public.test"
      Column      |       Type        |                       Modifiers                       
------------------+-------------------+-------------------------------------------------------
 id               | integer           | not null default nextval('test_id_seq'::regclass)
 foo_id   | integer           | 
 foo_role | character varying | 
Indexes:
    "test_pkey" PRIMARY KEY, btree (id)

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