Question

我在json中有一个带有城市名称的结果集，我想得到每个人的lat-long。以下功能在一定程度上起作用：

(:require [http.async.client :as client])

(defn get-geo-fact [row]
  (let [ 
    n (string/replace (:cityname row) " "  "+") 
    url (str "http://maps.googleapis.com/maps/api/geocode/json?address=" 
              n "&sensor=false")
    resp (client/GET url) ]
  (client/await resp)
  (make-geo-fact row (json/read-json (client/string resp))) ))

最后一次调用make-geo-fact只返回城市坐标的RDF渲染。我遇到的问题是运行（对此函数的约40次调用）返回lat-longs的一些（3-5个lat-long对）null结果。返回null值的城市因运行而异 - 有时San Jose会获得坐标，有时则不会。

我最初使用 slurp 来抓取网址的主体并获得类似偶尔的空值。我认为我没有正确等待响应，但切换到 http.async.client 似乎没有做到这一点。有什么想法吗？

修改：

这是make-geo-fact功能，它带有“这个团队位于这个城市”的事实和谷歌地图的响应，返回两个传递纬度和经度的三元组矢量：

(defn make-geo-fact [row response]
  (let [ g (:location (:geometry (first (:results response))))
         lat (str "<" (:team row) ">" 
                  " <http://www.nhl.com/latitude> \"" (:lat g) 
                  "\"^^<http://www.w3.org/2001/XMLSchema#decimal> ." )
         lon (str "<" (:team row) ">" 
                  " <http://www.nhl.com/longitude> \"" (:lng g) 
                  "\"^^<http://www.w3.org/2001/XMLSchema#decimal> ." )  ]
        [lat lon] ))

这就是我打电话来解决所有问题的功能：

(defn make-geo-facts []
  (let [ a (bounce team-city (build "files/team-city.nt")) 
         f "files/geo-facts.nt" ]
    (spit f (string/join "\n" (flatten (map get-geo-fact (:rows a)))))  
    f ))

bounce 函数针对RDF模型发出SPARQL select查询，该模型使用 build 函数进行实例化。

编辑2

这是一个不需要make-geo-fact的重要因素：

  (defn get-geo-fact [row]
    (let [ n (string/replace (:cityname row) " "  "+") 
           url (str "http://maps.googleapis.com/maps/api/geocode/json?address=" n "&sensor=false")
           resp (client/GET url)  ]
      (-> (client/GET url)
           client/await
           client/string
           json/read-json
           :results
           first
           :geometry
           :location )))

    (defn make-geo-facts []
        (let [ a (bounce tc-query (build "files/team-city.nt")) 
               f "files/geo-facts.nt"
               *client* (client/create-client)]
          (try (spit f (string/join "\n" (flatten (map get-geo-fact (:rows a))))))
          (finally (client/close *client*)) ))

Answer 1

正如您所说，改变客户端实现并没有什么不同。我仔细检查并为http.async.client的开发版本创建test。总是得到身体的回应。

请提供make-geo-fact implementation。

Answer 2

原来我的代码需要一点睡眠。我将（线程/睡眠1000）添加到我的核心函数中，现在我没有得到null结果：

(defn get-geo-fact [row]
    (let [ n (string/replace (:cityname row) " "  "+") 
            url (str "http://maps.googleapis.com/maps/api/geocode/json?address=" n "&sensor=false")
            resp (client/GET url)  ]
            (Thread/sleep 1000) 
        (-> (client/GET url)
              client/await
              client/string
              json/read-json
              (make-geo-fact ,,, row ) )))

使用clojure的http.async.client和google偶尔会出现null结果

2 个答案: