设计`find_first_by_auth_conditions`方法解释 [英] Devise `find_first_by_auth_conditions` method explanation

问题描述

我使用 Devise 的两种方法:

My two methods using Devise:

方法一

def self.find_first_by_auth_conditions(warden_conditions)
  conditions = warden_conditions.dup
  where(conditions).where(["lower(username) = :value OR lower(email)
    = :value", {:value => signin.downcase }]).first
end

方法二

def self.find_for_database_authentication(warden_conditions)
  conditions = warden_conditions.dup
  login = conditions.delete(:signin)
  where(conditions).where(["lower(username) = :value OR lower(email) = 
    :value", {:value => login.strip.downcase }]).first
end

我的问题:

1. 这段代码执行/做什么?login = conditions.delete(:signin)
2. 没有上面的代码，我得到一个错误 undefined local variable or method signin

推荐答案

以下回答问题1)——特别是A)和B) 下面.以下代码是一个示例，并不反映 Devise 生成的实际方法或参数:

The following answers question 1)—specifically A) and B) below. The following code is an example and does not mirror the actual methods or arguments generated by Devise:

这里:Hash 包含 :signin 键值对和其他有效的 ActiveRecord 的 #where 语法http://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-where

Here: the Hash contains :signin key-value pair and other valid ActiveRecord's #where syntax http://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-where

devise_conditions = {:signin => "[e-mail]", :deleted => false, :role => 'basic'} 
#=> {:signin=>"[e-mail]", :deleted => false, :role => 'basic'} 

这会复制原始参数以防止修改以便在后续方法或查询中使用它http://ruby-doc.org/core-1.9.3/Object.html#method-i-dup

conditions = devise_conditions.dup 
#=> {:signin=>"[e-mail]", :deleted => false, :role => 'basic'}

这里，代码:A) 从 Hash 中删除 :signin 密钥对；和B) 使用 :signin 密钥对的值从 Hash 分配新变量 signinhttp://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-delete

Here, the code: A) deletes the :signin key-pair from the Hash; and B) assigns new variable signin with value of :signin key-pair from Hash http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-delete

signin = conditions.delete(:signin) 
#=> "[e-mail]" 

可以使用 Hash 的附加元素引用"重写上面的代码以阐明这两个操作http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-5B-5D

The immediately above code could be rewritten to clarify both operations using additional "Element Reference" of Hash http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-5B-5D

signin = conditions[:signin]
#=> "[e-mail]"

conditions.delete(:signin)
#=> "[e-mail]" # deleted value from Hash is returned

conditions
#=> {:deleted => false, :role => 'basic'} 

使用dup

devise_conditions 
#=> {:signin=>"[e-mail]", :deleted => false, :role => 'basic'}

<小时>

以下回答问题2):

Method1 不会创建变量 signin.未定义的局部变量或方法登录是由于创建它的代码被删除时没有创建signin变量.

Method1 does not create a variable signin. undefined local variable or method signin results from no signin variable being created when the code which creates it is removed.

Method2 创建一个变量 login，该变量具有来自名为 conditions 的原始 Hash 的值，键为 <代码>:登录.

Method2 creates a variable login which has the value from the original Hash named conditions with the key :signin.

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