Ruby-on-rails 计算过去 7 天内创建的记录
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Count records created within the last 7 days
提问by Dru
How can I alter the query below to only select records created within the last 7 days?
如何更改下面的查询以仅选择过去 7 天内创建的记录？
self.favorites.count
This function is located in my Usermodel.
此功能位于我的User模型中。
def calculate_user_score
unless self.new_record?
self.score = (self.links.count * 5) + (self.favorites.count * 0.5)
end
end
回答by Ben Lee
You can add a where-condition like this:
您可以where像这样添加-condition：
self.favorites.where('created_at >= ?', 1.week.ago).count
And for your calculate_user_scoremethod, you probably want to do that for linksas well:
对于您的calculate_user_score方法，您可能也想这样做links：
def calculate_user_score
unless new_record?
self.score = (links.where('created_at >= ?', 1.week.ago).count * 5) +
(favorites.where('created_at >= ?', 1.week.ago).count * 0.5)
end
end
回答by Augustin Riedinger
I recommend you add a scope to your model:
我建议您为模型添加一个范围：
class User < ActiveRecord::Base
scope :recents, where("created_at > ?", Time.now-7.days)
end
Then you can do
然后你可以做
self.favorites.recents.count
回答by aldrien.h
In Rails 4+
在Rails 中 4+
This code seems not working:
这段代码似乎不起作用：
"created_at > ?", Time.now-7.days
I tried like:
我试过：
scope :recent, -> { where("DATE(created_at) > ?", (Date.today).to_time - 7.days) }
回答by zed_0xff
self.links.where("created_at > ?", Time.now-7.days).count
回答by armahillo
If you're working in Rails, you can just use the agodatetime methods, instead of doing weird time math.
如果你在 Rails 中工作，你可以只使用agodatetime 方法，而不是做奇怪的时间数学。
scope :recent, -> { where("created_at > ?", 1.week.ago) }
In Rails, you can usually avoid a lot of the complicated data preparation and type-casting you might have to do in other languages / frameworks.
在 Rails 中，您通常可以避免在其他语言/框架中可能必须进行的许多复杂的数据准备和类型转换。
Re: the original post, I would probably refactor it like this:
回复：原帖，我可能会像这样重构它：
# Using association extensions here to filter this down,
# the ellipses parenthetical should be whatever you're using for your
# association definition.
has_many :links ( ... ) do
def since(last_date)
where('created_at > ?', last_date)
end
end
has_many :favorites (...) do
def since(last_date)
where('created_at > ?', last_date)
end
end
# Don't use magic numbers; codify them for context.
LINK_SCORE_MULTIPLIER = 5
FAVE_SCORE_MULTIPLIER = 0.5
# Note this does not persist it in the database; if you want it to persist
# you'll want to execute an update instead. However it does memoize it so multiple
# calls will pull from the in-memory cache of the object instead of re-querying it
def score(recalculate: true)
@score ||= (links.since(1.week.ago).count * LINK_SCORE_MULTIPLIER) +
(favorites.since(1.week.ago).count * FAVE_SCORE_MULTIPLIER)
end
Then you just reference it passively:
然后你只是被动地引用它：
@user.score # runs the query and saves to memory
@user.score # pulls from memory
@user.score(recalculate: true) # re-runs the query and saves to memory
@user.save # persists the result (assuming you have a field for :score)
It might require refactoring, but depending on how your data is modeled, you might be able to use a counter_cacheto track it (this would require a has_many,throughassociation, and the counter_cachewould be on the joining model.
它可能需要重构，但根据您的数据建模方式，您可能可以使用 acounter_cache来跟踪它（这将需要一个has_many,through关联，并且counter_cache将在连接模型上。
回答by Datt
I was looking for records which could return last 7 daysi.e. not including today. But this worked for me and it can work for last n days.
我正在寻找可以返回的记录，last 7 days即不包括今天。但这对我有用，并且可以用于last n days.
last_n_days = 7
Model.where('created_at BETWEEN ? AND ?', Date.today-last_n_days, Date.today-1).count
with scope
有范围
scope :last_n_days, lambda {|n| where('created_at BETWEEN ? AND ?', Date.today - n, Date.today - 1)}
