torvaldsdb (K-night)

Ruby, Bunlder, ROR 升级遇见的坑/升级说明 (集中讨论)

torvaldsdb — Mon, 30 Mar 2020 18:20:51 +0800

随着最新版本 Ruby 2.7.0, Bundler 2.1.4, Rails 6.0.2的到来, 项目中升级遇到哪些坑，集中讨论，欢迎补充：

Rails 验证 on: :context

torvaldsdb — Sun, 29 Jul 2018 22:50:26 +0800

数据验证给出一个实例 model -- User

class User < ActiveRecord::Base
  validate :first_name, presence: true  # case 1
  validate :last_name, presence: true, on: :create # case 2
  validate :nickname, presence: true, on: :update # case 3
  validates :balance, numericality: true, on: :admin # case 4 一种定制的 context
end

构造 User 数据：

FactoryGirl.define do
  factory :user do
    first_name { Faker::Name.first_name }
    last_name { Faker::Name.first_name }
    nickname { Faker::Name.name }
    balance { Faker::Number.number(6) }

    factory :user_without_first_name do
      first_name nil
    end

    factory :user_without_last_name do
      last_name nil
    end

    factory :user_without_nickname do
      nickname nil
    end

    factory :user_without_balance do
      balance nil
    end

    factory :user_with_negative_balance do
      balance { Faker::Number.negative(10, 20) }
    end
  end
end

详细解释一下示例中的四种校验假设：user 是 User 的一个实例。

first_name 的验证，没有定义 context(没有on: **的存在), 这种验证在 user 每次 save 的时候都会被触发。
last_name 的验证，定义了 context(on: :create), 该验证只有 user 是新建数据，满足#new_record?为 true, save 的时候触发。

nickname 的验证，同样定义了 context(on: :update), 该验证理论上应该在更新数据 (数据 user#persisted?为 true) 的时候才会触发，测试中 on: :update == on: [:create, :update], 无论是新建数据还是更新数据都会触发。

# 验证on: :create
# 新建一个没有 last_name 的 user
user_without_last_name = FactoryGirl.build(:user_without_last_name)
user_without_last_name.valid? # => false
# 更新一个没有 last_name 的 user
user_without_last_name.save(validate: false)
user_without_last_name.valid? # => true

# 验证on: :update
# 新建一个没有 nickname 的 user
user_without_nickname = FactoryGirl.build(:user_without_nickname)
user_without_nickname.valid? # => false
# 更新一个没有 nickname 的 user
user_without_nickname.save(validate: false)
user_without_nickname.valid? # => false

balance 的验证，自定义了 context(on: :admin), 这种方式需要特殊的触发方式: context 源码

# Runs all the validations within the specified context. Returns +true+ if
# no errors are found, +false+ otherwise.
#
# If the argument is +false+ (default is +nil+), the context is set to <tt>:create</tt> if
# <tt>new_record?</tt> is +true+, and to <tt>:update</tt> if it is not.
#
# Validations with no <tt>:on</tt> option will run no matter the context. Validations with
# some <tt>:on</tt> option will only run in the specified context.
def valid?(context = nil)
  context ||= (new_record? ? :create : :update)
  output = super(context)
  errors.empty? && output
end

使用：

user = FactoryGirl.build(:user)
# valid?
user.valid?(:admin)

# save
user.save(context: :admin)

注意点:

user = FactoryGirl.build(:user)

当你运行user.valid?(:admin)的时候，只会验证first_name, 与balance, 并不会验证last_name nickname

on: :admin 做为允许的条件，可以在保存的时候 #save(context: :admin), 如果默认保存的手做其他的限制，可以：

validates :balance, numericality: true, on: :admin

validates :balance, numericality: { greater_than_or_equal_to: 0 }, 
                    on: [:create, :update]

这样 user.save 就会限制 balance 大于 0

context 在 autosave 中的使用：添加 Article

class Article < ActiveRecord::Base
belongs_to :user, autosave: true
end

构造 Article 数据：

FactoryGirl.define do
factory :article do
user
end
end

使用：

user = FactoryGirl.create(:user)
article = FactoryGirl.create(:article, user: user)

article.user.assign_attributes(balance: -1)

# valid?
article.valid? # => true
# valid?(:admin)
article.valid?(:admin) # => false

# save
article.save # => true
# save(:admin)
article.save(:admin) # => false

context 在测试中写法

require 'rails_helper'

RSpec.describe User, type: :model do
  it { expect(build(:user_without_balance)).to be_valid(:admin) }
end

关于 inject, 疑惑的地方.

torvaldsdb — Sat, 03 Feb 2018 10:59:07 +0800

在控制台遇到的问题，看着相似，结果却截然不同。意图：累加，如果小于 2, 就 +1, 如果大于 3, 就 +2

(1..5).inject(0) do |sum, a|
  next sum + 1 if a <2
  next sum + 2 if a >3
  sum
end

输出结果：=> 5

(1..5).inject(0) do |sum, a|
  next sum + 1 if a <2
  sum + 2 if a >3
  sum
end

输出结果：=>1

(1..5).inject(0) do |sum, a|
  next sum + 2 if a >3
  next sum + 1 if a <2
  sum
end

输出结果：=>5

(1..5).inject(0) do |sum, a|
  next sum + 2 if a >3
  sum + 1 if a <2
  sum
end

输出结果：=>4

究竟问题出在哪里？

环绕别名

torvaldsdb — Fri, 19 Jan 2018 11:26:19 +0800

参看元编程的时候，发现环绕别名，感觉很新颖

自己在项目中测试了一下，却没有顺利执行，如下

class User < ApplicationRecord
  alias :real_avatar :avatar

  def avatar
    real_avatar.present? ? "real_avatar" : "default.png"
  end
end

控制器执行的结果: User 实例：

2.4.2 (main):0 > user = User.last
  User Load (0.3ms)  SELECT  "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]
=> #<User:0x00007fde39a372c0
 id: 2,
 uid: "017526292153702",
 avatar: "http://img2.imgtn.bdimg.com/it/u=3563567972,3348399262&fm=27&gp=0.jpg",
 nickname: "Nick-member",
 created_at: Fri, 19 Jan 2018 00:26:16 CST +08:00,
 updated_at: Fri, 19 Jan 2018 00:26:16 CST +08:00>

调用的 atatar, 并没有展示我想要的 "real_avatar", 而是报了错误

user.avatar

=> NameError: undefined method `avatar' for class `#<Class:0x00007fe4db80b6d8>'

哪里出了错了吗？

ransackable_scopes 小结

torvaldsdb — Tue, 09 May 2017 01:28:51 +0800

ransack今天遇到传递两个参数的 scope，然后查询使用ransackable_scopes的时候，文档ransack中没有太多说明。自己就捣弄了一会儿。抛砖引玉！

store 的一个实例

[3] pry(main)> Store
=> Store(id: integer, block_id: integer, district: jsonb)
[13] pry(main)> Store.first
  Store Load (2.9ms)  SELECT  "stores".* FROM "stores" ORDER BY "stores"."created_at" DESC LIMIT $1  [["LIMIT", 1]]
=> #<Store:0x00000007aa6430
 id: 4,
 district: {"1"=>{"id"=>"710000", "name"=>"台湾省"}}>

原来的scope如下：

scope :store_district, -> (district_level, district_id) {
  where("district->'#{district_level}'->>'id' = ?", district_id)
}

查询：

[5] pry(main)> Store.count
   (2.5ms)  SELECT COUNT(*) FROM "stores"
=> 4
[6] pry(main)> Store.store_district("1", "710000")
  Store Load (3.1ms)  SELECT "stores".* FROM "stores" WHERE (district->'1'->>'id' = '710000') ORDER BY "stores"."created_at" DESC
=> [#<Store:0x000000071b9ed0
  id: 4,
  district: {"1"=>{"id"=>"710000", "name"=>"台湾省"}}>]

在 model 中声明：

class << self
  # ransackable scope
  def ransackable_scopes(auth_obj = nil)
    %i(store_district)
  end
end

只是接口没有想到好的参数传递方式。后来就改写了 scope`

scope :store_district, -> (*params) {
  params_hash = params.to_h.deep_symbolize_keys
  district_level, district_id = params_hash[:level], params_hash[:id]
  where("district->'#{district_level}'->>'id' = ?", district_id)
}

api 接口： localhost:3000/district/stores?store_district[level]=1&store_district[id]=710000 方法展示

# GET district/stores?page[number]=1&store_district[level]=1&store_district[id]=710000
def search_store_by_district
  stores = Store.search(params).result
  render ***
end

邮箱里的一道题目, 有没有好的算法.

torvaldsdb — Fri, 17 Mar 2017 09:40:46 +0800

关于排列组合的题目。昨晚用自己的方式已经解决。大家有没有好的算法探讨一下。

You are planning a big programming conference and have received many proposals which have passed the initial screen process but you're having trouble fitting them into the time constraints of the day -- there are so many possibilities! So you write a program to do it for you.

    The conference has multiple tracks each of which has a morning and afternoon session.
    Each session contains multiple talks.
    Morning sessions begin at 9am and must finish before 12 noon, for lunch.
    Afternoon sessions begin at 1pm and must finish in time for the networking event.
    The networking event can start no earlier than 4:00 and no later than 5:00.
    No talk title has numbers in it.
    All talk lengths are either in minutes (not hours) or lightning (5 minutes).
    Presenters will be very punctual; there needs to be no gap between sessions.

Note that depending on how you choose to complete this problem, your solution may give a different ordering or combination of talks into tracks. This is acceptable; you don’t need to exactly duplicate the sample output given here.

Test input:
Writing Fast Tests Against Enterprise Rails 60min
Overdoing it in Python 45min
Lua for the Masses 30min
Ruby Errors from Mismatched Gem Versions 45min
Common Ruby Errors 45min
Rails for Python Developers lightning
Communicating Over Distance 60min
Accounting-Driven Development 45min
Woah 30min
Sit Down and Write 30min
Pair Programming vs Noise 45min
Rails Magic 60min
Ruby on Rails: Why We Should Move On 60min
Clojure Ate Scala (on my project) 45min
Programming in the Boondocks of Seattle 30min
Ruby vs. Clojure for Back-End Development 30min
Ruby on Rails Legacy App Maintenance 60min
A World Without HackerNews 30min
User Interface CSS in Rails Apps 30min

Test output:
Track 1:
09:00AM Writing Fast Tests Against Enterprise Rails 60min
10:00AM Overdoing it in Python 45min
10:45AM Lua for the Masses 30min
11:15AM Ruby Errors from Mismatched Gem Versions 45min
12:00PM Lunch
01:00PM Ruby on Rails: Why We Should Move On 60min
02:00PM Common Ruby Errors 45min
02:45PM Pair Programming vs Noise 45min
03:30PM Programming in the Boondocks of Seattle 30min
04:00PM Ruby vs. Clojure for Back-End Development 30min
04:30PM User Interface CSS in Rails Apps 30min
05:00PM Networking Event

Track 2:
09:00AM Communicating Over Distance 60min
10:00AM Rails Magic 60min
11:00AM Woah 30min
11:30AM Sit Down and Write 30min
12:00PM Lunch
01:00PM Accounting-Driven Development 45min
01:45PM Clojure Ate Scala (on my project) 45min
02:30PM A World Without HackerNews 30min
03:00PM Ruby on Rails Legacy App Maintenance 60min
04:00PM Rails for Python Developers lightning
05:00PM Networking Event

我的大致思路是：

上午下午分别进行排列组合
上午下午的组合拼接在一起
把有数据重复的组合剔除掉这个过程耗时很久。抛砖引玉

Sublime Text 3 关于空格占位的图示

torvaldsdb — Mon, 19 Dec 2016 19:47:09 +0800

sublime text3 关于空格占位的图示：

preferences -> settings 设置：

{
  "auto_find_in_selection": true,
  "bold_folder_labels": true,
  "color_scheme": "Packages/Color Scheme - Default/Monokai.tmTheme",
  "dictionary": "Packages/Language - English/en_US.dic",
  "ensure_newline_at_eof_on_save": true,
  "font_face": "Consolas",
  "font_size": 18,
  "highlight_line": true,
  "highlight_modified_tabs": true,
  "ignored_packages":
  [
    "Markdown",
    "Vintage"
  ],
  "margin": 2,
  "match_brackets_angle": true,
  "rulers":
  [
    0,
    80
  ],
  "show_encoding": true,
  "show_full_path": true,
  "show_line_endings": true,
  "tab_size": 2,
  "translate_tabs_to_spaces": true,
  "trim_trailing_white_space_on_save": true,
  "use_simple_full_screen": true,
  "word_wrap": true
}

想要的效果如图：

是不是配置少了什么~

Window 10 下的开发 Rails

torvaldsdb — Sat, 10 Dec 2016 19:06:39 +0800

Guide

window 下开发需要条件

首先下载虚拟机 vagrant： Vagrant 下载，Vagrant 是一个基于 Ruby 的工具，用于创建和部署虚拟化开发环境。它使用 Oracle 的开源 VirtualBox 虚拟化系统，使用 Chef 创建自动化虚拟环境。那么我们需要下载 VirtualBox
然后下载 VirtualBox： VirtualBox 下载
我们还需要一个命令还工具：cmder，cmder 下载 cmder 很多 github 上得给的下载链接都失效了，我这个暂时是可用的
vagrant 封装好的 Ubuntu 镜像我们把它叫做ubuntu14.03-server-rails.box
当然还有我们喜爱的编辑器sublime text 3

都下载安装好之后，我们需要配置一下 cmder

下载好cmder后，解压即可使用。只是这样使用很不方便，然后我们接着做以下操作
把 cmder 加到环境变量：把 Cmder.exe 存放的目录添加到系统环境变量；加完之后，Win+r 一下输入 cmder，这样就可以启动 cmder
添加 cmder 到右键菜单：在命令提示符 (管理员)(A)的终端中输入Cmder.exe /REGISTER ALL，这样以后我们可以在任意文件点击鼠标右键可以看到cmder here

到此为止cmder必须的配置已经搞定

我们可以开工了。

首先我们向虚拟机里面添加ubuntu14.03-server-rails.box： vagrant box add ubuntu-rails ubuntu14.03-server-rails.box，ubuntu-rails 是生成系统的名字，这里我的 cmder 已经切换到ubuntu14.03-server-rails.box所在的目录下
接着在你工作的目录下进行一下操作 mkdir workspace cd workspace mkdir ubuntu-rails cd ubuntu-rails
将本目录初始化化为 ubuntu 系统 vagrant init ubuntu-rails

接下来可以直接启动系统了

启动系统 vagrant up
登录系统 vagrant ssh 到了这一步，你就可以看到，你的系统已经不再是你的 win 系统而是你的 ubuntu 系统

D:\workspace\ubuntu-rails (master)
λ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
    default: Adapter 2: hostonly
==> default: Forwarding ports...
    default: 3000 (guest) => 3001 (host) (adapter 1)
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
    default: The guest additions on this VM do not match the installed version of
    default: VirtualBox! In most cases this is fine, but in rare cases it can
    default: prevent things such as shared folders from working properly. If you see
    default: shared folder errors, please make sure the guest additions within the
    default: virtual machine match the version of VirtualBox you have installed on
    default: your host and reload your VM.
    default:
    default: Guest Additions Version: 5.0.8
    default: VirtualBox Version: 5.1
==> default: Configuring and enabling network interfaces...
==> default: Mounting shared folders...
    default: /vagrant => D:/workspace/ubuntu-rails
    default: /home/vagrant/workspace => D:/workspace/ubuntu-rails
==> default: Machine already provisioned. Run `vagrant provision` or use the `--provision`
==> default: flag to force provisioning. Provisioners marked to run always will still run.

D:\workspace\ubuntu-rails (master)
λ vagrant ssh
Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.19.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

  System information as of Sat Dec 10 18:56:48 CST 2016

  System load:  0.74              Processes:           88
  Usage of /:   34.1% of 6.76GB   Users logged in:     0
  Memory usage: 9%                IP address for eth0: 10.0.2.15
  Swap usage:   0%                IP address for eth1: 192.168.33.10

  Graph this data and manage this system at:
    https://landscape.canonical.com/

179 packages can be updated.
126 updates are security updates.

New release '16.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

Last login: Sat Dec 10 16:33:37 2016 from 10.0.2.2
vagrant@ubuntu:~$ ls
workspace
vagrant@ubuntu:~$ cd workspace/myblog/
vagrant@ubuntu:~/workspace/myblog$ rails s
=> Booting WEBrick
=> Rails 4.2.4 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2016-12-10 18:58:40] INFO  WEBrick 1.3.1
[2016-12-10 18:58:40] INFO  ruby 2.2.1 (2015-02-26) [x86_64-linux]
[2016-12-10 18:58:40] INFO  WEBrick::HTTPServer#start: pid=2699 port=3000

这样我们的项目就跑起来了，不过这样跑起来，浏览器并不能与我们的服务互动。我们需要一点小操作：

我们在启动服务的时候，不要用 localhost 这个主机

我们需要指定主机 rails s -b 0.0.0.0

这样服务跑起来是：

vagrant@ubuntu:~/workspace/myblog$ rails s -b 0.0.0.0
=> Booting WEBrick
=> Rails 4.2.4 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2016-12-10 19:05:06] INFO  WEBrick 1.3.1
[2016-12-10 19:05:06] INFO  ruby 2.2.1 (2015-02-26) [x86_64-linux]
[2016-12-10 19:05:06] INFO  WEBrick::HTTPServer#start: pid=2710 port=3000

然后我们可以在我们 windows 下的浏览器中访问我们的服务了 http://localhost:3001

特别☆强调

浏览器访问的时候用的端口是：3001 上面vagrant up启动虚拟机的时候已经告知：

==> default: Forwarding ports...
    default: 3000 (guest) => 3001 (host) (adapter 1)
    default: 22 (guest) => 2222 (host) (adapter 1)

温馨提示

在 cmder 中切换 windows 下路径可以 cd .. 不过如果更换根目录的时候需要类似 cd /d D:\download这个/d不可省略，或者用pushd D:\download
下载好了sublime text 3之后我们需要实现 subl .启动文件的功能
打开 Cmder 安装目录下的 config 文件夹下的 aliases 文件。
在 aliases 中增加一行，添加别名。 subl="D:\PROGRA~1\sublimeText3\sublime_text.exe"

如果你的屏幕足够大或者你分辨率足够高你可以选择 subl="D:\PROGRA~1\sublimeText3\sublime_text.exe" $1 -new_console:s50H这样你左边是终端，右边是 sublime

这样你已经可以很舒服地在 windows 下开发了，还有一些小细节，可以参考相关文献

未解决的问题

第一次用这个 windows 下的 sublime，全局搜索快捷键ctrl + shift + f，无法使用

回调 before_update 的误区

torvaldsdb — Wed, 21 Sep 2016 15:50:37 +0800

before_update

如果想在该回调函数中重新更新对象的属性，这时候要避免使用 update 或者 update_attributes, 换一个方法使用 update_column

update_column这个方法提供

Validations are skipped.(跳过验证)
Callbacks are skipped.(跳过回调)
updated_at/updated_on are not updated.(两个字段不再更新)

这样可以避免 before_update 的死循环。

save(validate: false)可以跳过验证

微信扫一扫功能如何实现?有没有大神分享一下心得?

torvaldsdb — Mon, 27 Jun 2016 16:37:20 +0800