P48
# TODO: options
类型首字母不大写

app

例子:

rails g model questionnaire
question:string

veryAgree:boolean agree:boolean

disagree:boolean veryDisagree:boolean

和模型一起生成 rails generate model name field:type [...]
[options]
 单独生成 rails generate migration name [field:type
...] [options]

例: rails generate migration AddBirthToAuthors birth: date

生成的文件名 20180216002328_add_birth_to_authrs.rb

文件内容

#20180216002328_add_birth_to_authrs.rb

class AddBirthToAuthors < ActiveRecord:: Migration[5.0]

  def change

    add_ column :authors, :birth, :date

  end

end

------------------------------------------------------------------------------

------------------------------------------------------------------------------

Class.where(exp)

● joins/includes等关联搜索的参数写法

where(关联表格名: {关联处的搜索条件} )

cars = cars.includes(:equipment_spec).where(equipment_specs: { power_window: true })

返回找到的全部(非数组?)

Class.where(exp [, value, ...])
 占位符: ?或者符号(symbol) :sample
 注意: 一定要用占位符，别把输入的字符直接展开进去。SQL可能会爆炸的233

不等于是not, 只用于不是nil

http://railsdoc.com/references/where

ModelTest.where('ap  <= ?',
1000).or(ModelTest.where('def > :def', :def => 4000))

Class.where(...).select(cols)

默认获取所有的列, 用这个方法可以指定具体要获得的列

AVG(sample)  AS avg_price 

 Class.avg_price

ModelTest.where('hp >= ? AND mp >= ? AND ad >= ?', 1000,
200, 1500).offset(1).limit(1)

exp写法参照p206
# TODO:
 @having = ModelTest.all.group(:israre).having('hp
>= ?', 0)\

注意:unscoped是删除之前的所以条件

delete(keys) 单纯删除(直接执行SQL, 不经过Active Recode)
 destroy(keys)  先选择后删除,
新手还没理解delete的时候全用destroy就行

例子: sample.delete
     
  Class.delete(id)
注: 用对象呼出时候不用指定id

Member Load (0.3ms)  SELECT  `members`.* FROM `members` ORDER BY `members`.`id` ASC LIMIT 1

  SQL (0.6ms)  DELETE FROM `members` WHERE `members`.`id` = 207

Member Load (0.4ms)  SELECT  `members`.* FROM `members` ORDER BY `members`.`id` ASC LIMIT 1

   (0.2ms)  BEGIN

  SQL (0.3ms)  DELETE FROM `members` WHERE `members`.`id` = 206

   (0.4ms)  COMMIT

例子: sample.delete
     
  Class.delete(id)
注: 用对象呼出时候不用指定id

用发出异常来终止transaction
也可以用模块对象来呼出transaction

经常用@sample.save!  失败返回例外

通用参数:

注: 可以直接设置成全部适用, 如  validates :id, allow_blank: true, length: { is: 10 }, uniqueness: true

或对特地验证适用, 如 validates :id, length: {allow_blank: true, is: 10}, uniqueness: true

validates :sample, presence: { if: "sample.method" }

with_options:

with_options(on: :create, if: 'true') do |oc|

  oc.validates :name, presence: true

  oc.validates :user_id, presence: true

end

ActiveModel可用的validation:

must be accepted

doesn't match confirmation

is reserved

is not included in the list

is invalid

is too short(minimum is xxx characters)等

is not a number 等

can't be blank

must be blank

# 只需要此列值唯一

validates :column1, uniqueness: true

# 和一个列绑定

validates :column2, uniqueness: {allow_blank: true, scope: :a}

# 和多个列绑定

validates :column3, uniqueness: {allow_blank: true, scope: [:a, :b]}

has already been taken

validates field [, ...] name: params [, ...]

参数含义:

errors (ActiveModel::Errors类)

前提: 设定了validates, 不然不会有任何错误

sample.errors.any?

sample.errors.count

sample.errors.size

sample.errors.full_messages

sample.errors.to_a

sample.errors[:column_name]

sample.errors.details[:column_name]

sample.errors.add(:column_name, 'error_message')

sample.errors[:column_name] << 'error_message'

sample.errors.clear

直接呼出方法

validates :method_name [, ...]

设置

# config/application.rb

# ...

module Core

  class Application < Rails::Application

    # ...

    # add custom validators path

    config.autoload_paths += Dir["#{config.root}/app/models/validators"]

    config.enable_dependency_loading = true

    # ...

 end

end

创建文件

# app/models/validators/sample_validator.rb

class SampleValidator < ActiveModel::EachValidator

  def validate_each(record, attribute, value)

    puts "UUID custom validate fired, options: #{options}" # 获取options的方法

    record.errors[attribute.to_sym] << "test" # 错误通过此方法发出

  end

end

使用

# sample.rb

# ...

class Sample < ApplicationRecord

  # ...

  validates :user_id, sample: {ko: "ok", sample1: 1}

  # ...

end

# 运行 rails c

a = Sample.new

a.valid? # => false

# UUID custom validate fired, options: {:ko=>"ok", :sample1=>1}

joins(exp)

前提是已经建立association

● 参数是关联名(如has_one则为单数)

● 搜索时候套上的symbol是表格名

cars = cars.includes(:equipment_spec).where(equipment_specs: request)

Car.joins(:equipment_spec).select('cars.*, equipment_specs.*')

EquipmentSpec.joins(car: :maker)
.select('equipment_specs.*, cars.id AS car_id, makers.name AS maker_name')

EquipmentSpec.joins(:car).select('equipment_specs.*, cars.*')

用join也能达到association的效果

与相关model结合

(左外部结合)

Rails 5.0

left_outer_joins(exp)

alias: left_joins(exp)

结合是左外部结合 LEFT OUTER JOIN

写法和上面一样, 但不能用C写法

● 参数是关联名(如has_one则为单数)

● 搜索时候套上的symbol是表格名

includes(exp)

结合是左外部结合 LEFT OUTER JOIN

写法一样，但不能用C写法

● 参数是关联名(如has_one则为单数)

● 搜索时候套上的symbol是表格名

tname: table name

frname: 外部table name

fname: field name

type: field的数据类型

opt: field的option

i_opt: index option

t_opt:table option

fr_opt: foreign key option

create_table tname [,toption] do |t|

   t.type fname [, opt, ...]

   ...

end

create_table，

change_table

代码块内可用的方法

create_table，change_table代码块内可用的方法

例:

change_table tname do |t|

    ...

end

● 可用的方法

● 可用的列定义

t.数据类型 :列名, opt

 可利用的数据类型和对应关系

t.references :book #生成book_id，相当于 t.belongs_to :book

选项opt