一、Ruby語言本身

• require、load和include。
  require：形式為require 'active_support/concern'。 請求一個模組，需要不帶副檔名的檔名，程式中多次requrie這個模組不會多次裝載，ruby會使用記憶體中的快取；
  load：形式為require 'active_support/concern.rb'。請求裝載一個模組，需要帶副檔名，每次執行到load，不管以前是否裝載過，ruby都會再次讀取此模組；
  include：形式為：include ActiveSupport::Concern。mixin一個模組，使用的是模組的名稱而不是檔名，其實和前兩個沒啥關係，很多時候需要一起使用；
  
  
• 檢視一個類的方法。
  methods、public_methods、private_methods、instance_methods、public_instance_methods
  

  irb(main):025:0> Test2.instance_methods
  => [:m1, :to_json, :blank?, :as_json, :acts_like?, :deep_dup, :present?, :duplicable?, :with_options, :html_safe?, :in?, :presence_in, :dclone, :`, :to_yaml, :to_param, :to_query, :instance_values,
   :instance_variable_names, :presence, :pretty_print_cycle, :pretty_print_inspect, :pretty_print, :pretty_print_instance_variables, :require_dependency, :unloadable, :require_or_load, 
  :load_dependency, :try, :try!, :instance_variable_defined?, :remove_instance_variable, :instance_of?, :kind_of?, :is_a?, :tap, :instance_variable_get, :instance_variables, :instance_variable_set,
   :protected_methods, :private_methods, :public_send, :method, :public_method, :singleton_method, :class_eval, :pretty_inspect, :define_singleton_method, :extend, :suppress_warnings, :to_enum,
   :enum_for, :<=>, :===, :=~, :!~, :eql?, :respond_to?, :gem, :freeze, :inspect, :object_id, :send, :to_s, :display, :class, :nil?, :hash, :dup, :singleton_class, :clone, :then, :itself,
   :yield_self, :untaint, :taint, :tainted?, :trust, :untrust, :untrusted?, :singleton_methods, :frozen?, :methods, :public_methods, :equal?, :!, :==, :instance_exec, :!=, :instance_eval,
   :__id__, :__send__]
  
  

  　　

  # 為了便於檢視，可以排一下序
  irb(main):034:0> Test2.instance_methods.sort
  => [:!, :!=, :!~, :<=>, :==, :===, :=~, :__id__, :__send__, :`, :acts_like?, :as_json, :blank?, :class, :class_eval, :clone, :dclone, :deep_dup, :define_singleton_method, :display, :dup, 
  :duplicable?, :enum_for, :eql?, :equal?, :extend, :freeze, :frozen?, :gem, :hash, :html_safe?, :in?, :inspect, :instance_eval, :instance_exec, :instance_of?, :instance_values, 
  :instance_variable_defined?, :instance_variable_get, :instance_variable_names, :instance_variable_set, :instance_variables, :is_a?, :itself, :kind_of?, :load_dependency, :m1, :method,
   :methods, :nil?, :object_id, :presence, :presence_in, :present?, :pretty_inspect, :pretty_print, :pretty_print_cycle, :pretty_print_inspect, :pretty_print_instance_variables, :private_methods, 
  :protected_methods, :public_method, :public_methods, :public_send, :remove_instance_variable, :require_dependency, :require_or_load, :respond_to?, :send, :singleton_class, :singleton_method,
   :singleton_methods, :suppress_warnings, :taint, :tainted?, :tap, :then, :to_enum, :to_json, :to_param, :to_query, :to_s, :to_yaml, :trust, :try, :try!, :unloadable, :untaint, :untrust, 
  :untrusted?, :with_options, :yield_self]
  irb(main):035:0>
  

  　

二、UI檢視(ActionView)相關

• AJAX訪問錯誤引發錯誤“ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken)” ， 在controller中新增下面命令，跳過校驗

  skip_before_action :verify_authenticity_token

三、ActiveRecord

• 命令列生成migration時，複雜資料型別（decimal）的語法 ：
  

  # decimal的單引號時必要的
  rails g model Abc 'price:decimal{5,2}' supplier:references{polymorphic}

• Model中自定義屬性（資料庫表中不存在），需要序列化為json的需要覆蓋as_json
  

   # 擴充套件json物件，新增pinyin和jianpin屬性
    def as_json data    
      if self.respond_to? 'name'
        ps = { pinyin: self.pinyin_name, jianpin: self.jianpin }
        super.merge ps
      end
    end

• ActiveRecord物件 的修改痕跡追蹤，記錄在此

四、系統相關

• 建立臨時檔案時，如何指定副檔名。rails建立臨時檔案很方便，直接Tempfile::newnew(basename="", tmpdir=nil, mode: 0, **options)，但是如何給定一個副檔名呢？原來只需要在第一項引數位置給出一個數組即可，看程式碼
  
  

  irb(main):001:0> tf = Tempfile::new
  => #<Tempfile:/tmp/20201120-38479-dg7h2v>
  irb(main):002:0> tf.path
  => "/tmp/20201120-38479-dg7h2v"
  irb(main):003:0> tf = Tempfile::new('abc')
  => #<Tempfile:/tmp/abc20201120-38479-abc6ui>
  irb(main):004:0> tf.path
  => "/tmp/abc20201120-38479-abc6ui"
  irb(main):006:0> tf = Tempfile::new(['abc','txt'])
  => #<Tempfile:/tmp/abc20201120-38479-2prba5txt>
  irb(main):007:0> tf.path
  => "/tmp/abc20201120-38479-2prba5txt"
  irb(main):008:0> tf = Tempfile::new(['abc','.txt'])
  => #<Tempfile:/tmp/abc20201120-38479-n6a5j6.txt>
  irb(main):009:0>

  irb(main):020:0> tf = Tempfile.new ['','.jpg']
  => #<Tempfile:/tmp/20201120-38479-qkitzp.jpg>

五、程式釋出

• config/enviroment/production.rb, 靜態檔案服務開啟
  

  config.public_file_server.enabled = true