迭代和设置Ruby对象实例变量 [英] Iterate and Set Ruby Object Instance Variables

问题描述

我正在寻找一种方法来遍历Ruby对象的实例变量，并使用通用设置器分别设置它们(从提供的哈希值中).我假设我可以直接在一个方法中遍历它们，并简单地分别设置它们.

I'm looking for a way to iterate through a Ruby object's instance variables, and set them individually (from a provided hash) using a generic setter. I am assuming I can iterate through them directly in a method and simply set each individually.

这是我的对象实例，你:

Here is my object instance, u:

u = #<Waffle:0x00007fc6b1145530 
    @id=nil,
    @alpha="",
    @bravo="",
    @charlie="",
    @delta=nil,
    @echo=nil,
    @status=new>

我想用给定的哈希h填充它:

I would like to populate it with a given hash, h:

h = {
    "id"=>"141",
     "alpha"=>"Muccahiya""
     "bravo"=>"$2a$10$xR2g",
     "charlie"=>"2018-02-21 10:41:56-05",
     "delta"=>"2018-02-05 18:17:16.752606-05",
     "echo"=>"wobbly",
     "status"=>"active"
}

这是我拥有的方法，它会引发此错误:

This is the method I have and it is throwing this error:

def to_obj(h)
    self.instance_variables.each do |i|
        self.i = h[i.sub('@','')]
    end
end

错误:

Traceback (most recent call last):
3: from /users/rich/app.rb:31:in `<main>'
2: from /Library/WebServer/Documents/dingbat/models/waffle.rb:240:in `to_obj'
1: from /Library/WebServer/Documents/dingbat/models/waffle.rb:240:in `each'
/Library/WebServer/Documents/dingbat/models/waffle.rb:241:in `block in to_obj': no implicit conversion of String into Integer (TypeError)

self.instance_variables确实是一个符号数组.

self.instance_variables is indeed an array of symbols.

我认为对象可以给定哈希值来设置其instance_variables.这不难.

I am thinking that an object can set its instance_variables given a hash. This can't be difficult.

推荐答案

def to_obj(h)
  h.each{|k, v| instance_variable_set("@{k}", v)}
end

如果仅在定义了此类实例变量的情况下才想设置值，请执行以下操作:

If you want to set a value only if such instance variable is defined, then do:

def to_obj(h)
  h.each do
    |k, v|
    next unless instance_variable_defined?("@{k}")
    instance_variable_set("@{k}", v)
  end
end

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