ring.middleware.format_params.cjl 抛出格式错误的 JSON

Question

我使用带有 ring/compojure/swagger 设置的 luminus 模板。

当我提供 REST API 时，我创建了格式错误的 JSON，我得到 500 并且：

java.lang.IllegalArgumentException: No value supplied for key: {:formats (:json-kw :yaml-kw :edn :transit-json :transit-msgpack), :handle-error #<middleware$handle_req_error compojure.api.middleware$handle_req_error@3130fc88>}, compiling:(pythonapi.clj:14:1)
    at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3558)
    at clojure.lang.Compiler$DefExpr.eval(Compiler.java:417)
    at clojure.lang.Compiler.eval(Compiler.java:6708)
    at clojure.lang.Compiler.load(Compiler.java:7130)
    at clojure.lang.RT.loadResourceScript(RT.java:370)
    at clojure.lang.RT.loadResourceScript(RT.java:361)
    at clojure.lang.RT.load(RT.java:440)
    at clojure.lang.RT.load(RT.java:411)
    at clojure.core$load$fn__5066.invoke(core.clj:5641)
    at clojure.core$load.doInvoke(core.clj:5640)
    at clojure.lang.RestFn.invoke(RestFn.java:408)
    at clojure.core$load_one.invoke(core.clj:5446)
    at clojure.core$load_lib$fn__5015.invoke(core.clj:5486)
    at clojure.core$load_lib.doInvoke(core.clj:5485)
    at clojure.lang.RestFn.applyTo(RestFn.java:142)
    at clojure.core$apply.invoke(core.clj:626)
    at clojure.core$load_libs.doInvoke(core.clj:5524)
    at clojure.lang.RestFn.applyTo(RestFn.java:137)
    at clojure.core$apply.invoke(core.clj:626)
    at clojure.core$require.doInvoke(core.clj:5607)
    at clojure.lang.RestFn.invoke(RestFn.java:1289)
    at voicepin_collector.handler$eval23$loading__4958__auto____24.invoke(handler.clj:1)
    at voicepin_collector.handler$eval23.invoke(handler.clj:1)
    at clojure.lang.Compiler.eval(Compiler.java:6703)
    at clojure.lang.Compiler.eval(Compiler.java:6692)
    at clojure.lang.Compiler.load(Compiler.java:7130)
    at clojure.lang.RT.loadResourceScript(RT.java:370)
    at clojure.lang.RT.loadResourceScript(RT.java:361)
    at clojure.lang.RT.load(RT.java:440)
    at clojure.lang.RT.load(RT.java:411)
    at clojure.core$load$fn__5066.invoke(core.clj:5641)
    at clojure.core$load.doInvoke(core.clj:5640)
    at clojure.lang.RestFn.invoke(RestFn.java:408)
    at clojure.core$load_one.invoke(core.clj:5446)
    at clojure.core$load_lib$fn__5015.invoke(core.clj:5486)
    at clojure.core$load_lib.doInvoke(core.clj:5485)
    at clojure.lang.RestFn.applyTo(RestFn.java:142)
    at clojure.core$apply.invoke(core.clj:626)
    at clojure.core$load_libs.doInvoke(core.clj:5524)
    at clojure.lang.RestFn.applyTo(RestFn.java:137)
    at clojure.core$apply.invoke(core.clj:626)
    at clojure.core$require.doInvoke(core.clj:5607)
    at clojure.lang.RestFn.invoke(RestFn.java:408)
    at voicepin_collector.listener$_contextInitialized.invoke(listener.clj:1)
    at voicepin_collector.listener.contextInitialized(Unknown Source)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4973)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5467)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.manager.ManagerServlet.start(ManagerServlet.java:1291)
    at org.apache.catalina.manager.HTMLManagerServlet.start(HTMLManagerServlet.java:694)
    at org.apache.catalina.manager.HTMLManagerServlet.doPost(HTMLManagerServlet.java:217)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:213)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:610)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: No value supplied for key: {:formats (:json-kw :yaml-kw :edn :transit-json :transit-msgpack), :handle-error #<middleware$handle_req_error compojure.api.middleware$handle_req_error@3130fc88>}
    at clojure.lang.PersistentHashMap.create(PersistentHashMap.java:77)
    at ring.middleware.format_params$wrap_restful_params.doInvoke(format_params.clj:251)
    at clojure.lang.RestFn.invoke(RestFn.java:423)
    at compojure.api.middleware$api_middleware.doInvoke(middleware.clj:214)
    at clojure.lang.RestFn.invoke(RestFn.java:423)
    at compojure.api.core$api_middleware_with_routes.invoke(core.clj:21)
    at clojure.lang.AFn.applyToHelper(AFn.java:156)
    at clojure.lang.AFn.applyTo(AFn.java:144)
    at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3553)
    ... 78 more

我认为我必须拦截此异常，以便通知用户已发布格式错误的 JSON 并返回 400。

哪里是执行 try/catch 的最佳位置？

Answer 1

我处理这个问题的通常方法是制作一个新的中间件，包装现有的中间件，捕获预期的错误并返回您的自定义消息和状态。

(defn safe-restful-params
  [handler]
  (fn [request]
    (try ((wrap-restful-params handler) request)
         (catch IllegalArgumentException e
            {:status 400 ; bad request
             :body "malformed JSON"}))))

实际上，您可能想要设置一些标头等，您还可以编写一个更通用的版本来包装任意中间件，而不是对这个中间件进行特殊封装，但这是一般概念。环中间件总是将处理程序作为其参数，并返回一个您可以在环请求上调用的函数，实际上通常应该在请求上调用处理程序作为其执行的一部分。该中间件还在其自身和处理程序之间手动插入另一个中间件，旨在替换该其他中间件。