哈希映射为现有键返回 nil

Question

我有一个 csv 文件，我使用 clojure.data.csv 库对其进行解析，并将每一行转换为包含字段名称和值的映射。问题是当我尝试从第一行获取字段 qid 时，我得到 nil，即使打印该行确实正确显示了哈希映射。

(ns exam-system.input.input-csv
  (:require [clojure.data.csv :as csv]
            [clojure.java.io :as io]))

(defn csv-data->maps
  [csv-data]
  (map zipmap
       (->> (first csv-data)
            (map keyword)
            repeat)
       (rest csv-data)))

(with-open [reader (io/reader "mypath\\questions.csv")]
  (doall
   (let [row (first (take 1 (csv-data->maps (csv/read-csv reader))))]
     (println "------------")
     (println row)
     (println (get row :qid))
     (println (contains? row :qid)))))

控制台结果：

------------
{:qid 11,001, :question With respect to flight spoilers they :, :answer Option A.     Only operate on the ground.                                                                              
Option B.     Only operate in flight.                                                                                 
Option C.     Can operate both on ground and in flight., :cSubmodule 11.9, :correct Option C.     Can operate both on ground and in flight.}
nil
false

除了明显的部分之外，代码与库的 github 页面中提供的代码大部分相同。我也读过this thread，但建议的解决方案不适用。所有其他键都返回适当的值。

更新：示例数据。这些是我文件中的前 4 个条目。顶部是我用来制作地图的标题。

qid,question,answer,cSubmodule,correct
"11.001",With respect to flight spoilers they :,"Option A.     Only operate on the ground.                                                                              
Option B.     Only operate in flight.                                                                                 
Option C.     Can operate both on ground and in flight.",11.9,Option C.     Can operate both on ground and in flight.
"11.002",The preferred method of Battery charging a Ni-Cad Battery is constant?,"Option A.     Voltage.                                                                         
Option B.     Current.                                                                             
Option C.     Power.",11.6,Option B.     Current.(CAAIP EEL/1-5 par.4.1)
"11.003","In an aircraft control system, employing servo-tabs installation of external ground locks to main control surface :","Option A.     is unnecessary since system is irreversible and therefore control surface cannot be displace by the wind.                                                                                          
Option B.     would not prevent movement of control column.                                                                                                                           
Option C.     would also prevent movement of control column.",11.9,Option B.     would not prevent movement of control column.(Pallet Anto Flight Control p.222)

Answer 1

您的示例看起来没有明显错误，尽管take 1 和doall 的用法是不必要的。我能够从您的样本数据中获得价值。我建议利用 REPL 提供的交互性来一步一步地找出问题所在：

(def row-maps (csv-data->maps (csv/read-csv ...)))

(first row-maps) ;; this should print the first row/map to your REPL
=>
{:qid "11.001",
 :question "With respect to flight spoilers they :",
 :answer "Option A.     Only operate on the ground.                                                                              
          Option B.     Only operate in flight.                                                                                 
          Option C.     Can operate both on ground and in flight.",
 :cSubmodule "11.9",
 :correct "Option C.     Can operate both on ground and in flight."}

(:qid *1)        ;; *1 will contain the value of the previous evaluation
=> "11.001"