From aa08f4b58c50c2583022c7ba0591f0203812bff6 Mon Sep 17 00:00:00 2001
From: Chris Broome <chrisbroome7@gmail.com>
Date: Mon, 3 Dec 2018 22:12:45 -0500
Subject: [PATCH] Add more descriptive error message when uri has no db name

---
 src/clojure/monger/core.clj    | 11 +++++++----
 test/monger/test/core_test.clj |  4 ++++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/clojure/monger/core.clj b/src/clojure/monger/core.clj
index 880a259..5573bc6 100644
--- a/src/clojure/monger/core.clj
+++ b/src/clojure/monger/core.clj
@@ -233,10 +233,13 @@
    Commonly used for PaaS-based applications, for example, running on Heroku.
    If username and password are provided, performs authentication."
   [^String uri-string]
-  (let [uri  (MongoClientURI. uri-string)
-        conn (MongoClient. uri)
-        db   (.getDB conn (.getDatabase uri))]
-    {:conn conn :db db}))
+  (let [uri    (MongoClientURI. uri-string)
+        conn   (MongoClient. uri)
+        dbName (.getDatabase uri)]
+    (if (nil? dbName)
+      (throw (Exception. "No database name specified in uri"))
+      (let [db (.getDB conn dbName)]
+        {:conn conn :db db}))))
 
 (defn ^com.mongodb.CommandResult command
   "Runs a database command (please check MongoDB documentation for the complete list of commands).
diff --git a/test/monger/test/core_test.clj b/test/monger/test/core_test.clj
index eeaa5b6..c8082ce 100644
--- a/test/monger/test/core_test.clj
+++ b/test/monger/test/core_test.clj
@@ -70,3 +70,7 @@
               :cursor-finalizer-enabled true
               :required-replica-set-name "rs"}]
     (is (instance? com.mongodb.MongoClientOptions$Builder (mg/mongo-options-builder opts)))))
+
+(deftest connect-to-uri-without-db-name
+  (let [uri "mongodb://localhost:27017"]
+    (is (thrown? Exception (mg/connect-via-uri uri)))))