Merge pull request #131 from nvlass/edn-pr-str-with-lazy-sequences

Logging in lazy sequences may interfere with output of Content-Type: application/edn

modules/muuntaja/src/muuntaja/format/edn.clj

@@ -16,8 +16,10 @@
     core/EncodeToBytes
     (encode-to-bytes [_ data charset]
       (.getBytes
-        (pr-str data)
-        ^String charset))
+       (let [w (new java.io.StringWriter)]
+         (print-method data w)
+         (.toString w))
+       ^String charset))
     core/EncodeToOutputStream
     (encode-to-output-stream [_ data charset]
       (fn [^OutputStream output-stream]

test/muuntaja/ring_middleware/format_response_test.clj

@@ -133,6 +133,25 @@
     ;; we do not set the "Content-Length"
     #_(is (< 2 (Integer/parseInt (get-in resp [:headers "Content-Length"]))))))
 
+(defn- produce-element-with-log [n]
+  (prn "reading from db" n)
+  {:element n})
+
+(defn- dummy-handler-with-lazy-seq [_]
+  {:status 200
+   :body (map produce-element-with-log (range 4))})
+
+(deftest lazy-sequences-with-logs
+  (let [handler (wrap-api-response
+                 dummy-handler-with-lazy-seq
+                 (-> m/default-options
+                     (m/select-formats ["application/edn"])))
+        resp    (handler {})
+        body    (slurp (:body resp))]
+    ;; Lazy sequence realization interferes with `with-out-str`
+    #_(is (= body "(\"reading from db\" 0\n\"reading from db\" 1\n\"reading from db\" 2\n\"reading from db\" 3\n{:element 0} {:element 1} {:element 2} {:element 3})"))
+    (is (= body "({:element 0} {:element 1} {:element 2} {:element 3})"))))
+
 (def yaml-echo
   (wrap-api-response
     identity