Question

I have created some clojure function to access a database, as shown in the snippet below:

(defn get-dg [date]
  (let [query (str "......")
        ]
    (jdbc/with-connection db
      (jdbc/with-query-results rows 
          [query date date date date]
          (.debug log rows)
          (if (not (seq rows)) 
           nil
           rows))))
)

Everything works fine. The query returns a result set which I can then process. Now, if I comment out (.debug log rows) I get this:

java.lang.RuntimeException: java.sql.SQLException: Closed Resultset: next

Any idea why?

Thanks

Answer 1

“rows” are lazy. And It’s seems that “(.debug log rows)” evaluated the “rows”. Just do it explicitly:

(defn get-dg [date]
  (let [query (str "......") ]
    (jdbc/with-connection db
      (jdbc/with-query-results rows [query date date date date]
        (comment .debug log rows)
        (if (empty? rows) nil (doall rows))))))