rails 中的 t.belongs_to 和 t.references 有什么区别? [英] What is the difference between t.belongs_to and t.references in rails?
问题描述
t.references
和 t.belongs_to
有什么区别?为什么我们有这两个不同的词?在我看来他们做同样的事情?尝试了一些 Google 搜索,但没有找到任何解释.
What is the difference between t.references
and t.belongs_to
?
Why are we having those two different words? It seems to me they do the same thing?
Tried some Google search, but find no explanation.
class CreateFoos < ActiveRecord::Migration
def change
create_table :foos do |t|
t.references :bar
t.belongs_to :baz
# The two above seems to give similar results
t.belongs_to :fooable, :polymorphic => true
# I have not tried polymorphic with t.references
t.timestamps
end
end
end
推荐答案
看源代码,它们做同样的事情——belongs_to
是 reference
的别名:
Looking at the source code, they do the same exact thing -- belongs_to
is an alias of reference
:
def references(*args)
options = args.extract_options!
polymorphic = options.delete(:polymorphic)
args.each do |col|
column("#{col}_id", :integer, options)
column("#{col}_type", :string, polymorphic.is_a?(Hash) ? polymorphic : options) unless polymorphic.nil?
end
end
alias :belongs_to :references
这只是让你的代码更具可读性的一种方式——能够在适当的时候将 belongs_to
放在你的迁移中,并坚持 references
用于其他各种关联.
This is just a way of making your code more readable -- it's nice to be able to put belongs_to
in your migrations when appropriate, and stick to references
for other sorts of associations.
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