我可以在Rails中创建一个未命名的作用域吗? [英] Can I create an *un*named scope in Rails?

问题描述

我知道您可以在Rails中创建命名作用域，它允许您指定条件，然后可以在以后建立这些条件:

I know you can create named scopes in Rails, which allow you to specify conditions which can then be built on later:

named_scope :active, :conditions => {:active => true}

...

MyModel.active.find(...)

这通过创建直到以后才评估的代理对象而起作用.我想知道的是，是否可以创建动态的 un 命名范围?

This works by creating a proxy object which isn't evaluated until later on. What I want to know is if it's possible to create a dynamic unnamed scope?

我的意思是说，有一种我可以使用的方法'foo'

By which I mean, is there a method 'foo' with which I can go

scope = MyModel.foo(:conditions => {:target_id => 4})

然后将scope作为代理对象传递给我，我可以对其进行更多的.find或其他作用域调用吗?

and then pass scope around as a proxy object that I can do more .finds or other scoped calls on?

推荐答案

是，请检查匿名范围:

def find_products
  scope = Product.scoped({})
  scope = scope.conditions "products.name LIKE ?", "%#{keywords}%" unless keywords.blank?
  scope = scope.conditions "products.price >= ?", minimum_price unless minimum_price.blank?
  scope = scope.conditions "products.price <= ?", maximum_price unless maximum_price.blank?
  scope = scope.conditions "products.category_id = ?", category_id unless category_id.blank?
  scope
end

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