Clojure/postgresql: How do I access the enum values from the Jdbc4Array results?

Question

I have an enum in postgresql defined like so:

create type color as enum ('yellow', 'purple', 'white', 'black');

And I can get to the Jdbc4Array like so:

(def colors 
  ((first (sql/with-connection db/db 
    (sql/with-query-results res 
      ["select enum_range(null::color)"]
      (doall res)))) :enum_range))

This shows an object like this:

#<Jdbc4Array {yellow,purple,white,black}>

But trying the usual things throws an exception:

(.getArray colors) => stream closed

So I figure I need to access the array before the connection is closed:

(def colors 
  ((sql/with-connection db/db 
    (sql/with-query-results res 
      ["select enum_range(null::color)"]
      (.getArray ((first (doall res)) :enum_range))))))

But in this case I get this exception:

Method org.postgresql.jdbc4.Jdbc4Array.getArrayImpl(long,int,Map)
is not yet implemented.

Sinister. What can I do here?

Answer 1

There is something very strange going on with the Postgresql Jdbc4Array.getArray() implementation, I couldn't get it to work. But, I have some success with .getResultSet() :

user=> (with-connection db (with-query-results rs ["select enum_range(null::color)"]     
           (.getResultSet (get (first(doall rs)) :enum_range))))
#<Jdbc4ResultSet org.postgresql.jdbc4.Jdbc4ResultSet@17cff66>

Now, array's contents could be accessed via standard ResultSet interface. I've copied some code from clojure.contrib.sql to do it:

(defn resultset-seq
  [^java.sql.ResultSet rs]
  (let [rsmeta (. rs (getMetaData))
    idxs (range 1 (inc (. rsmeta (getColumnCount))))
    keys (map (fn [i] (. rsmeta (getColumnLabel i))) idxs)
    check-keys (or (apply distinct? keys)
               (throw (Exception. "ResultSet must have unique column labels")))
    row-struct (apply create-struct keys)
    row-values (fn [] (map (fn [^Integer i] (. rs (getObject i))) idxs))
    rows (fn thisfn []
           (when (. rs (next))
         (cons (apply struct row-struct (row-values)) (lazy-seq (thisfn)))))]
  (rows)))

which gives (sorry for quick-hack style code)

user=> (with-connection db 
         (with-query-results rs ["select enum_range(null::color)"] 
                            (get (first (resultset-seq 
                                           (.getResultSet (get (first(doall rs))
                                                              :enum_range))))
                                 "VALUE")))
#<PGobject yellow>