遍历数据库中的每条记录 - Ruby on Rails / ActiveRecord
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Iterating through every record in a database - Ruby on Rails / ActiveRecord
提问by dougiebuckets
n00b question. I'm trying to loop through every User record in my database. The pseudo code might look a little something like this:
n00b 问题。我正在尝试遍历数据库中的每个用户记录。伪代码可能看起来像这样：
def send_notifications
render :nothing => true
# Randomly select Message record from DB
@message = Message.offset(rand(Message.count)).first
random_message = @message.content
@user = User.all.entries.each do
@user = User.find(:id)
number_to_text = ""
@user.number = number_to_text #number is a User's phone number
puts @user.number
end
end
Can someone fill me in on the best approach for doing this? A little help with the syntax would be great too :)
有人可以告诉我这样做的最佳方法吗？语法方面的一些帮助也会很棒:)
回答by Adrien Coquio
Here is the correct syntax to iterate over all User :
这是迭代所有 User 的正确语法：
User.all.each do |user|
#the code here is called once for each user
# user is accessible by 'user' variable
end
To improve performance and decrease load, use User.find_each(see doc) instead of User.all. Note that using find_eachloses the ability to sort.
要提高性能并减少负载，请使用User.find_each（参见文档）而不是User.all. 请注意，使用find_each会失去排序的能力。
回答by Andres Ehrenpreis
Also a possible one-liner for same purpose:
还有一个可能的单线用于相同目的：
User.all.map { |u| u.number = ""; puts u.number }
