Ruby-on-rails 如何在不担心主键的情况下更新记录
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how to update a record without worrying about primary key
提问by railsnew
In ActiveRecord how can we update a record without worrying/knowing primary key.
在 ActiveRecord 中，我们如何在不担心/知道主键的情况下更新记录。
If I do
如果我做
Address.update(15, :user_name => 'Samuel')
it corresponds to
它对应于
UPDATE addresses set user_name = 'Samuel' where id = 15
but what if i want to do:
但如果我想做：
UPDATE addresses set user_name = 'Samuel' where cid = 15
what will be the ActiveRecord equivalent of that??
什么是 ActiveRecord 等价物？
I tried:
我试过：
Address.update({:cid => 15}, :user_name => 'Samuel')
but that does not work.
但这不起作用。
回答by typeoneerror
Use the update_allclass method:
使用update_all类方法：
Address.where(:cid => 15).update_all(user_name : 'Samuel')
回答by Francisco Soto
a = Address.find_by_cid(15)
a.user_name = 'Samuel'
a.save
回答by boulder_ruby
To clarify on @typeoneerror's answer, just use update_allon an ActiveRecord::Relation object rather than a record object:
为了澄清@typeoneerror 的答案，只需update_all在 ActiveRecord::Relation 对象而不是记录对象上使用：
ModelName.where(:unique_id => x).update_all(:name => "x")
