diff --git a/caravel/templates/caravel/models/database/macros.html b/caravel/templates/caravel/models/database/macros.html
index 6bfa857308450..7a074cb33f6c1 100644
--- a/caravel/templates/caravel/models/database/macros.html
+++ b/caravel/templates/caravel/models/database/macros.html
@@ -2,12 +2,22 @@
   <script>
     $("#sqlalchemy_uri").parent()
       .append('<button id="testconn" class="btn">Test Connection</button>');
-    $("#testconn").click(function() {
+    $("#testconn").click(function(e) {
+      e.preventDefault();
       var url = "/caravel/testconn";
+
+      var data = {};
+      try{
+        data = JSON.stringify({ uri: $("#sqlalchemy_uri").val(), extras: JSON.parse($("#extra").val()) })
+      } catch(parse_error){
+        alert("Malformed JSON in the extras field: " + parse_error);
+        return false
+      }
+
       $.ajax({
         method: "POST",
         url: url,
-        data: JSON.stringify({ uri: $("#sqlalchemy_uri").val(), extras: JSON.parse($("#extra").val()) }),
+        data: data,
         dataType: 'json',
         contentType: "application/json; charset=utf-8"
       }).done(function(data) {
diff --git a/caravel/views.py b/caravel/views.py
index 8281dfa305f10..f902982339be5 100644
--- a/caravel/views.py
+++ b/caravel/views.py
@@ -638,7 +638,7 @@ def testconn(self):
         """Tests a sqla connection"""
         try:
             uri = request.json.get('uri')
-            connect_args = request.json.get('extras', {}).get('engine_params', {}).get('connect_args')
+            connect_args = request.json.get('extras', {}).get('engine_params', {}).get('connect_args', {})
             engine = create_engine(uri, connect_args=connect_args)
             engine.connect()
             return json.dumps(engine.table_names(), indent=4)