Add support for extra parsed params for MySQL app DBs

Similar to 5e181964 which allows extra parameters for PostgreSQL
application databases, this commit refactors that code to allow it for
MySQL as well.

src/metabase/db/spec.clj

@@ -2,7 +2,8 @@
   "Functions for creating JDBC DB specs for a given engine.
   Only databases that are supported as application DBs should have functions in this namespace;
   otherwise, similar functions are only needed by drivers, and belong in those namespaces."
-  (:require [ring.util.codec :as codec]))
+  (:require [clojure.string :as str]
+            [ring.util.codec :as codec]))
 
 
 (defn h2
@@ -16,6 +17,15 @@
           :subname     db}
          (dissoc opts :db)))
 
+(defn- remove-required-keys [db-spec & more-keys]
+  (apply dissoc db-spec (concat [:host :port :db :user :password :additional-options]
+                                more-keys)))
+
+(defn- make-subname [host port db extra-connection-params]
+  (let [query-params (codec/form-encode extra-connection-params)]
+    (str "//" host ":" port "/" db (when-not (str/blank? query-params)
+                                     (str "?" query-params)))))
+
 (defn postgres
   "Create a database specification for a postgres database. Opts should include
   keys for :db, :user, and :password. You can also optionally set host and
@@ -23,11 +33,13 @@
   [{:keys [host port db]
     :or   {host "localhost", port 5432, db ""}
     :as   opts}]
-  (let [query-params (codec/form-encode (merge (dissoc opts :host :port :db :user :password :additional-options :sslfactory) {:OpenSourceSubProtocolOverride true}))]
-     (merge {:classname   "org.postgresql.Driver"
-             :subprotocol "postgresql"
-             :subname     (str "//" host ":" port "/" db "?" query-params)}
-        (dissoc opts :host :port :db))))
+  (let [extra-conn-params (-> opts
+                              (remove-required-keys :sslfactory)
+                              (merge {:OpenSourceSubProtocolOverride true}))]
+    (merge {:classname   "org.postgresql.Driver"
+            :subprotocol "postgresql"
+            :subname     (make-subname host port db extra-conn-params)}
+           (dissoc opts :host :port :db))))
 
 (defn mysql
   "Create a database specification for a mysql database. Opts should include keys
@@ -36,11 +48,12 @@
   [{:keys [host port db]
     :or   {host "localhost", port 3306, db ""}
     :as   opts}]
-  (merge {:classname   "com.mysql.jdbc.Driver"
-          :subprotocol "mysql"
-          :subname     (str "//" host ":" port "/" db)
-          :delimiters  "`"}
-         (dissoc opts :host :port :db)))
+  (let [extra-connection-params (remove-required-keys opts)]
+    (merge {:classname   "com.mysql.jdbc.Driver"
+            :subprotocol "mysql"
+            :subname     (make-subname host port db extra-connection-params)
+            :delimiters  "`"}
+           (dissoc opts :host :port :db))))
 
 
 ;; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

src/metabase/driver/mysql.clj

@@ -88,10 +88,12 @@
   "Append `default-connection-args-string` to the connection string in CONNECTION-DETAILS, and an additional option to
   explicitly disable SSL if appropriate. (Newer versions of MySQL will complain if you don't explicitly disable SSL.)"
   {:argslist '([connection-spec details])}
-  [{connection-string :subname, :as connection-spec} {ssl? :ssl}]
-  (assoc connection-spec
-    :subname (str connection-string "?" default-connection-args-string (when-not ssl?
-                                                                         "&useSSL=false"))))
+  [connection-spec {ssl? :ssl}]
+  (update connection-spec :subname
+          (fn [subname]
+            (let [join-char (if (str/includes? subname "?") "&" "?")]
+              (str subname join-char default-connection-args-string (when-not ssl?
+                                                                      "&useSSL=false"))))))
 
 (defn- connection-details->spec [details]
   (-> details