Ruby-on-rails 有没有办法使 before_save 有条件？
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Is there a way to make a before_save conditional?
提问by Darren
I am trying to make a before_save in a rails app conditional, but it doesn't seem to be working.
我正在尝试在 Rails 应用程序中有条件地进行 before_save，但它似乎不起作用。
before_save method_call_to_run if self.related_model.some_method_that_returns_t_or_f?
If the 'some_method_that_returns_t_or_f' returns true, I want it to run the method before it saves the object otherwise I just want it to ignore the before_save.
如果“some_method_that_returns_t_or_f”返回true，我希望它在保存对象之前运行该方法，否则我只希望它忽略before_save。
回答by Andrea Pavoni
you can use :if
你可以使用：如果
before_save do_something, :if => Proc.new {|model| model.some_boolean_attr_or_method }
or simply
或者干脆
before_save do_something, :if => some_condition
EDIT:
编辑：
for a quick reference, there's an excellent guide about this:
为了快速参考，有一个很好的指南：
http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks
http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks
回答by sambecker
Rails 5
导轨 5
I've had success defining a private method which contains the boolean logic and then passing it as a symbol (that last part seems like a requirement):
我已经成功定义了一个包含布尔逻辑的私有方法，然后将其作为符号传递（最后一部分似乎是一个要求）：
before_save do_something, if: :private_boolean_method?
I also recently found out you can simply pass a block (took me a while to figure out the syntax):
我最近还发现你可以简单地传递一个块（我花了一段时间才弄清楚语法）：
before_save do_something, if: -> { condition == "met" }
