From 134ff69e0a2ee7c1781b827a7fb2584a9a1ac3b8 Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Tue, 14 Jul 2020 11:45:07 +0300
Subject: [PATCH] fix key-transformer

---
 src/malli/transform.cljc       |  8 ++++----
 test/malli/transform_test.cljc | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/malli/transform.cljc b/src/malli/transform.cljc
index 80e2b81be..f45aa6050 100644
--- a/src/malli/transform.cljc
+++ b/src/malli/transform.cljc
@@ -303,16 +303,16 @@
         :encoders {:map transform}}))))
 
 (defn key-transformer [{:keys [decode encode]}]
-  (let [transform (fn [f]
-                    (if f {:leave (fn [x]
+  (let [transform (fn [f stage]
+                    (if f {stage (fn [x]
                                     (if (map? x)
                                       (reduce-kv
                                         (fn [m k v] (assoc m (f k) v))
                                         (empty x) x)
                                       x))}))]
     (transformer
-      {:decoders {:map (transform decode)}
-       :encoders {:map (transform encode)}})))
+      {:decoders {:map (transform decode :enter)}
+       :encoders {:map (transform encode :leave)}})))
 
 (defn default-value-transformer []
   (let [get-default (fn [schema] (some-> schema m/properties :default))
diff --git a/test/malli/transform_test.cljc b/test/malli/transform_test.cljc
index b8a610999..64efaa4da 100644
--- a/test/malli/transform_test.cljc
+++ b/test/malli/transform_test.cljc
@@ -283,7 +283,20 @@
       (is (= {"x_key" 18 "y_key" "john" "a_key" "doe"}
              (m/encode [:map [:x int?] [:y string?] [[:opt :z] boolean?]]
                        {:x 18 :y "john" :a "doe"}
-                       key-transformer))))))
+                       key-transformer)))))
+
+  (testing "from strings and back"
+    (let [schema [:map
+                  [:id :string]
+                  [:github-followers pos-int?]]
+          transformer (mt/transformer
+                        (mt/key-transformer {:decode keyword, :encode name})
+                        (mt/string-transformer))
+          value {"id" "123", "github-followers" "10"}]
+      (is (= {:id "123", :github-followers 10}
+             (as-> value $ (m/decode schema $ transformer))))
+      (is (= value
+             (as-> value $ (m/decode schema $ transformer) (m/encode schema $ transformer)))))))
 
 (deftest interceptor-style-transformers
   (testing "map"