add implementations of write-body-to-stream for numbers / booleans (#21828)

* add implementations of write-body-to-stream for numbers / booleans
* add tests for getting non-string settings over the api
* remove blank line from end of api/segment.clj

src/metabase/api/common/internal.clj

@@ -279,9 +279,4 @@
   (wrap-response-if-needed [m]
     (if (and (:status m) (contains? m :body))
       m
-      {:status 200, :body m}))
-
-  ;; Not sure why this is but the JSON serialization middleware barfs if response is just a plain boolean
-  Boolean
-  (wrap-response-if-needed [_]
-    (throw (Exception. (tru "Attempted to return a boolean as an API response. This is not allowed!")))))
+      {:status 200, :body m})))

src/metabase/api/segment.clj

@@ -132,5 +132,4 @@
   [id]
   (-> id Segment api/read-check related/related))
 
-
 (api/define-routes)

src/metabase/async/api_response.clj

@@ -188,7 +188,21 @@
   ManyToManyChannel
   (write-body-to-stream [chan _ ^OutputStream output-stream]
     (log/debug (u/format-color 'green (trs "starting streaming response")))
-    (write-chan-vals-to-writer! (async-keepalive-channel chan) (io/writer output-stream))))
+    (write-chan-vals-to-writer! (async-keepalive-channel chan) (io/writer output-stream)))
+
+  ;; java.lang.Double, java.lang.Long, and java.lang.Boolean will be given a Content-Type of "application/json; charset=utf-8"
+  ;; so they should be strings, and will be parsed into their respective values.
+  java.lang.Double
+  (write-body-to-stream [num response output-stream]
+    (ring.protocols/write-body-to-stream (str num) response output-stream))
+
+  java.lang.Long
+  (write-body-to-stream [num response output-stream]
+    (ring.protocols/write-body-to-stream (str num) response output-stream))
+
+  java.lang.Boolean
+  (write-body-to-stream [bool response output-stream]
+    (ring.protocols/write-body-to-stream (str bool) response output-stream)))
 
 ;; `defendpoint-async` responses
 (extend-protocol Sendable

test/metabase/api/setting_test.clj

 (ns metabase.api.setting-test
   (:require [clojure.test :refer :all]
-            [metabase.models.setting-test :refer [test-sensitive-setting test-setting-1 test-setting-2 test-setting-3
-                                                  test-user-local-allowed-setting test-user-local-only-setting]]
+            [metabase.models.setting :as setting :refer [defsetting]]
+            [metabase.models.setting-test
+             :refer
+             [test-sensitive-setting
+              test-setting-1
+              test-setting-2
+              test-setting-3
+              test-user-local-allowed-setting
+              test-user-local-only-setting]]
             [metabase.public-settings.premium-features-test :as premium-features-test]
             [metabase.test :as mt]
             [metabase.test.fixtures :as fixtures]
+            [metabase.util.i18n :refer [deferred-tru]]
             [schema.core :as s]))
 
 (use-fixtures :once (fixtures/initialize :db))
 
+(defsetting test-api-setting-boolean
+  (deferred-tru "Test setting - this only shows up in dev (3)")
+  :visibility :public
+  :type :boolean)
+
+(defsetting test-api-setting-double
+  (deferred-tru "Test setting - this only shows up in dev (3)")
+  :visibility :public
+  :type :double)
+
+(defsetting test-api-setting-integer
+  (deferred-tru "Test setting - this only shows up in dev (3)")
+  :visibility :public
+  :type :integer)
+
 ;; ## Helper Fns
 (defn- fetch-test-settings
   "Fetch all test settings."
@@ -17,6 +40,7 @@
         :when   (re-find #"^test-setting-\d$" (name (:key setting)))]
     setting))
 
+
 (defn- fetch-setting
   "Fetch a single setting."
   ([setting-name status]
@@ -57,7 +81,19 @@
 
     (testing "Check that non-superusers cannot fetch a single setting if it is not user-local"
       (is (= "You don't have permissions to do that."
-             (fetch-setting :rasta :test-setting-2 403))))))
+             (fetch-setting :rasta :test-setting-2 403))))
+    (testing "non-string values work over the api (#20735)"
+      ;; n.b. the api will return nil if a setting is its default value.
+      (test-api-setting-double 3.14)
+      (is (= 3.14 (fetch-setting :test-api-setting-double 200)))
+
+      (test-api-setting-boolean true)
+      (is (= true (fetch-setting :test-api-setting-boolean 200)))
+
+      (test-api-setting-integer 42)
+      (is (= 42 (fetch-setting :test-api-setting-integer 200))))))
+
+(test-api-setting-integer)
 
 (deftest fetch-calculated-settings-test
   (testing "GET /api/setting"