Ruby-on-rails 通过字符串获取 ActiveRecord 对象的属性
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get attribute of ActiveRecord object by string
提问by Kieran Klaassen
It is probably a really simple thing but can't find a solution.
这可能是一件非常简单的事情，但找不到解决方案。
I have an ActiveRecord object and want to get an attribute like this:
我有一个 ActiveRecord 对象，想要获得这样的属性：
attribute_name = "name"
user = User.find(1)
user.get_attribute_by_name(attribute_name) => "John"
Thanks!
谢谢！
回答by Frederick Cheung
All of these should work:
所有这些都应该有效：
user[attribute_name]
user.read_attribute(attribute_name)
user.send(attribute_name)
Personally I wouldn't use sendin this case. When available, prefer public_sendto send
我个人不会send在这种情况下使用。可用时，更喜欢public_send发送
回答by Brent Matzelle
You can use either []or read_attribute()but they are not equivalent.
The safer method of access is using the [] methodmethod because it will raise an ActiveModel::MissingAttributeErrorerror if the attribute does not exist. The read_attribute methodreturns nilif the attribute does not exist.
您可以使用[]or ，read_attribute()但它们不是等价的。更安全的访问方法是使用[] 方法方法，因为ActiveModel::MissingAttributeError如果该属性不存在，它将引发错误。该read_attribute方法返回nil如果属性不存在。
回答by Kaz
In Rails 5, just attribute_name = "name"works
在 Rails 5 中，attribute_name = "name"正常工作
