使用 Play Framework 的缓存 API 在多语言网站中缓存操作 [英] Caching an action in a multi-language website using Play Framework's Cached API

问题描述

为了在给定的秒数内缓存每个标签和语言的动作，我编写了以下辅助方法(其中标签是我给动作的名称):

In order to cache actions per label and language for a given number of seconds, I wrote the following helper method (where label, is the name I give to my action):

def cacheResponseFor(label: String, duration: Int)(action: EssentialAction) = { 
   Cached({r: RequestHeader => (label + getLanguage(r))}, duration){ action }
}

def getLanguage(request: RequestHeader): String = {
   request.cookies
     .get(helpers.SessionHelpers.LANGUAGE_SESSION)
        .map(_.value)
          .getOrElse(helpers.LanguageHelpers.FRENCH)
}

但是我遇到了一些奇怪的事情，当我尝试缓存 60 年代的 Action 并同时将语言从法语切换到英语时，我一直在 60 年代获得法语版本，然后它切换到英语.

But I'm experiencing something weird, when I try to cache an Action for 60s and switch languages in the meantime to English from French for example, I keep getting the French version for 60s then it switches to english.

经过调查，我发现方法 getLanguage 不会在每次调用该操作时调用，就好像 Key 仅在缓存期结束后评估一样.

After investigating, I found that method getLanguage is not called at each call to that action as if the Key gets evaluated only after the caching period ends.

这是不对的，我希望每次请求我的页面时都调用这个 cacheResponseFor，使用 getLanguage 评估语言，然后我得到正确的缓存版本，即我应该得到 2 个缓存操作(每种语言一个).

This is not right, I would want this cacheResponseFor to be called everytime I request my page, the language gets evaluated using getLanguage and I get the right cached version, i.e. I should end up with 2 cached actions (one per language).

我错过了什么吗?

推荐答案

我不知道您面临的问题是什么，但我做了一个小的概念验证，完全没有问题.

I do not know what is the issue you are facing but I did a small proof of concept and there is no issue at all.

package controllers

import play.api.cache.Cached
import play.api.mvc.{Action, Controller, EssentialAction, RequestHeader}

object Caches {
  import play.api.Play.current

  def cacheResponseFor(label: String, duration: Int)(action: EssentialAction) = {
    Cached({r: RequestHeader => label + getLanguage(r)}, duration){ action }
  }

  def getLanguage(request: RequestHeader): String = {
    request.cookies
      .get("language")
      .map(_.value)
      .getOrElse("fr")
  }
}

class CachedApplication () extends Controller {

  import Caches._

  def index = cacheResponseFor("homePage", 60) {
    Action { implicit req =>
      getLanguage(req) match {
        case "fr" =>
          Ok("Bonjour le monde")
        case _ =>
          Ok("Hello world")
      }
    }
  }
}

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