基本过滤器Play Framework 2中的访问请求正文 [英] Access Request Body in essential filter Play Framework 2

问题描述

我是Scala的新手. 如 https://www.playframework.com/documentation/2.3中的play framework官方文档中所述.x/ScalaHttpFilters :

I am new to Scala. As mentioned in play framework official documentation in https://www.playframework.com/documentation/2.3.x/ScalaHttpFilters :

Play提供了一个称为EssentialFilter的较低级别的过滤器API，该API 使您可以完全访问请求的正文.

Play provides a lower level filter API called EssentialFilter which gives you full access to the body of the request.

但是在requestHeader对象中没有任何访问请求正文的方法.

but there is not any method to accessing request body in requestHeader object.

import play.api.Logger
import play.api.mvc._
import play.api.libs.concurrent.Execution.Implicits.defaultContext

object LoggingFilter extends EssentialFilter {
  def apply(nextFilter: EssentialAction) = new EssentialAction {
    def apply(requestHeader: RequestHeader) = {
      val startTime = System.currentTimeMillis
      nextFilter(requestHeader).map { result =>
        val endTime = System.currentTimeMillis
        val requestTime = endTime - startTime
        Logger.info(s"${requestHeader.method} ${requestHeader.uri}" +
          s" took ${requestTime}ms and returned ${result.header.status}")
        result.withHeaders("Request-Time" -> requestTime.toString)
      }
    }
  }
}

推荐答案

创建EssentialFilter时实现的抽象方法EssentialFilter.apply返回EssentialAction，基本上是从RequestHeader到一个Iteratee[Array[Byte], Result]，播放将把http正文的传入字节块送入.

The abstract method EssentialFilter.apply that you implement when you create an EssentialFilter returns an EssentialAction which basically is a function that goes from RequestHeader to an Iteratee[Array[Byte], Result] into which play will feed the incoming byte chunks of the http body.

如果您不熟悉iteratee API，则上述签名基本上意味着一种可以接受Array[Byte]类型数据块并迟早会从中产生Result的东西.

If you aren't familiar with the iteratee API, the signature above basically means, a thing that will accept chunks of data of the type Array[Byte] and sooner or later produce a Result out of those.

正常播放Action是EssentialAction的子类，它使用BodyParser解析正文，然后将结果(Request既是请求标头又是解析的正文)馈送到依次返回Future[Result]

The normal play Action's is a subclass of EssentialAction that parses the body using a BodyParser and then feeding the result of that (Request which is both request headers and the parsed body) into a function that in turn returns a Future[Result]

因此，如果您只有一个过滤器，则过滤器中的next: EssentialAction基本上是实际的控制器操作.您可以采用它的Iteratee[Array[Bytes], Result]并用某些东西包装它，这使得在正文解析器接触到请求的主体之前，可以访问该请求的主体.

So if you only have one filter, then next: EssentialAction in your filter is basically the actual controller action. That you get to take its Iteratee[Array[Bytes], Result] and wrap it with something is what makes it possible to access the body of the request, before the body parser has gotten to touch it.

因此，要实现所需的目标，您需要学习一些有关Iteratees的工作原理以及如何使用Enumeratees转换或窥视输入到iteratee中的数据的信息.

So to achieve what you want will require you to learn a bit about how Iteratees works and how to use Enumeratees to transform or peek into data fed into an iteratee.

Play框架文档已经获得了有关迭代对象的一些很好的信息: https://www.playframework.com/documentation/2.3.x/Iteratees

The play framework docs has got some pretty good information about iteratees: https://www.playframework.com/documentation/2.3.x/Iteratees

James Roper(技术主管)也发表了一篇不错的博客文章，该文章可能会有所帮助: https://jazzy.id.au/2012/11/06/iteratees_for_imperative_programmers.html

There is also a nice blog article by James Roper (play tech lead) that might help: https://jazzy.id.au/2012/11/06/iteratees_for_imperative_programmers.html

过滤器如何发挥作用，使得无法使用过滤器查看已解析的正文.除非您进行枚举以解析主体，但仍然将字节传递给实际操作(这将使您将主体解析两次).

How filters works in play makes it impossible to look at the parsed body with a filter. Unless you make an enumeratee that will parse the body but still pass the bytes on to the actual action (this will have you parsing the body twice).

如果这是您想要的，最好使用ActionBuilder并创建自己的自定义Action，使您可以查看已解析的请求.

If this is what you want you may be better off working with the ActionBuilder and creating your own custom Action that will allow you to look at the parsed request.

这篇关于基本过滤器Play Framework 2中的访问请求正文的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！