优雅的 ruby function，需要帮助清理它，所以它看起来像 ruby

Question

I have to parameters: name and age

def self.search(name, age)

end

If name is not empty/nil, then add it to the search expression.

If age is not empty/nil, then add it to the search expression.

if both are nil, return all.

So far I have:

def self.search(name, age)

   if name.nil? && age.nil?
      return User.all
   end



end

Finding it hard to write this in a elegant way.

Answer 1

def self.search(name, age)
  conditions = {}
  conditions[:name] = name if name
  conditions[:age] = age if age
  User.find(:all, :conditions => conditions)
end

Answer 2

I'm not sure what sort of search you're doing but I prefer to handle these sort of things in a scope.

class User < ActiveRecord::Base
  scope :by_name, lamba{|name| name.nil?? scoped : where(:name=>name) }
  scope :by_age, lamba{|age| age.nil?? scoped : where(:age=>age) }

  def self.search(name, age)
    User.by_name(name).by_age(age)
  end
end

It's a bit more code overall I suppose but it's more reusable and everything is in it's place.

Answer 3

In Rails 3 you can do it like this:

def self.search(name, age)
  scope = User
  scope.where(:name => name) if name.present?
  scope.where(:age => age) if age.present?
  scope
end

Note the use of present? rather than nil? to skip empty strings as well as nil.

In the other comment you mentioned wanting to OR these conditions. ActiveRecord does not provide convenient facilities for that; all conditions are AND by default. You will need to construct your own conditions like so:

def self.search(name, age)
  scope = User
  if name.present? && age.present?
    scope.where('name = ? OR age = ?', name, age)
  else
    scope.where(:name => name) if name.present?
    scope.where(:age => age) if age.present?
  end
  scope
end