如何绑定动态变量？

Question

如何在compojure中绑定动态变量？请参阅下面的示例,这里request-id是为每个api请求生成的唯一uuid.我希望能够访问该请求ID在随后的方法记录等等.我已经使用绑定功能试过,但我仍然无法访问请求ID的some-page/some-method.

handler.clj

(ns some_app.handler
  (:require
    [compojure.api.sweet :refer :all]
    [compojure.route :as route]
    [some_api.some_page :as some-page]))

(def ^:dynamic *request-id*
  nil)

(defn ^:private generate-request-id []
  (str (java.util.UUID/randomUUID)))

(def app
  (binding [*request-id* (generate-request-id)]
    (api
      (context "/api" [] (GET "/some-page" [] (some-page/some-method))))))

一些-page.clj

(ns some_app.some_page
(:require
        [clojure.tools.logging :as log]))

(def some-method []
  (log/info {:request-id *request-id*}))

Answer 1

这里对绑定的调用是在错误的地方.处理请求时绑定应该有效,而不是在构建app/api时.

你想要一些中间件来做到这一点:

(defn with-request-id 
  [f]
  (fn [request]
    (binding [*request-id* (generate-request-id)]
      (f request)))

(def app
  (with-request-id
    (api ... ))

另请参阅Ring Concepts