Rails 范围 - 未定义的方法 [英] Rails scopes - undefined methods

问题描述

我有一个名为事件"的模型，它有一个名为即将到来"的范围，返回未来日期的事件.在 rails 控制台中，每当我输入

I have a model called "event" that has a scope named "upcoming" wich returns events that are dated in the future. In the rails console, whenever I type

Event.upcoming

它成功返回事件的子集.但是，如果我输入:

It returns the subset of events successfully. However if I type:

@events = Event.all
@events.upcoming

我收到一个未定义的方法即将到来"的错误.作用域仅适用于类而不适用于实例化的变量吗?提前致谢.约翰

I get an undefined method 'upcoming' error. Are scopes only working on the class and not on instantiated variables? Thanks in advance. Yohann

推荐答案

一旦调用 .all，@events 就不再是 ActiveRelation>，因此您不能在其上调用作用域.

Once you call .all, @events is no longer an ActiveRelation, hence you cannot call a scope on it.

所以，Event.where(SOME CONDITIONS).order(ORDERING).upcoming.limit(X) 仍然有效，但 Event.where(SOME CONDITIONS).order(ORDERING).all.upcoming.limit(X) 不起作用.

So, Event.where(SOME CONDITIONS).order(ORDERING).upcoming.limit(X) would still work, but Event.where(SOME CONDITIONS).order(ORDERING).all.upcoming.limit(X) would not work.

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