手动定义getter/setter(attr_accessor或attr_writers)时如何使用read_attribute [英] How to use read_attribute when manually defining getter/setter (attr_accessor or attr_writers)

问题描述

我建立了一个search模型，并希望至少填写一个字段.我发现了一个有助于验证的问题，

I set up a search model and want to require at least one field is filled out. I found a question that helps with the validation, Rails: how to require at least one field not to be blank. (I tried all answers, but Voyta's seems the best.)

除了我要通过attr_accessor或attr_writer重新定义getter/setter时，验证有效. (我在表单上有一些虚拟属性，需要与验证分开.)为了弄清楚问题出在哪里，我测试了一个具有常规属性item_length的属性.如果添加attr_accessor :item_length，验证将停止工作.因此，我想问题是如何在不使用点表示法的情况下读取属性的值.由于验证使用字符串，因此我无法使用正常的读取方式.

The validation is working, except when I want to redefine the getter/setter via attr_accessor or attr_writer. (I have virtual attributes on the form that need to be apart of the validation.) To figure out what the problem is, I tested with an attribute that is a regular attribute item_length. If I add attr_accessor :item_length, the validation stops to work. So, I guess the question is how to I read an attribute's value without using dot notation. Since the validation uses strings, I can't use the normal way of reading.

这是一个代码段:

if %w(keywords 
      item_length 
      item_length_feet 
      item_length_inches).all?{|attr| read_attribute(attr).blank?}
    errors.add(:base, "Please fill out at least one field")
  end

就像我说的那样，虚拟属性(length_inches和length_feet)根本不起作用，正常属性(length)起作用，除非我重新定义getter/setter.

Like I said, the virtual attrbutes (length_inches and length_feet) do not work at all, and the normal attribute (length) works except if I redefine the getter/setter.

推荐答案

如注释中所述，使用send

array.all? {|attr| send(attr).blank?}

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对于那些想知道send在这种情况下是否可以使用的人，是的，它是:对象调用其自己的实例方法.

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For those wondering if send is ok in this case, yes it is: object calls its own instance methods.

但是send是一个非常有用的工具，因此，当您与其他对象一起使用时，请确保将其公共api与public_send

But send is a sharp tool, so whenever you use with other objects, ensure you use their public api with public_send

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