Merge pull request #78 from edx/schen/EDUCATOR-3925

fix(bug): make sure gradebook rounding handle null input

documentation/decisions/0001-update-api-usage.rst

@@ -0,0 +1,46 @@
+Usage of the bulk-update API
+============================
+
+Context
+=======
+
+The LMS Grades API exposes a set of Gradebook-related endpoints:
+https://github.com/edx/edx-platform/blob/master/lms/djangoapps/grades/api/v1/gradebook_views.py
+The ``bulk-update`` endpoint defined therein allows for the creation/modification of subsection
+grades for multiple users and sections in a single request.  This allows clients of the API to limit
+the number of network requests made and to more easily manage client-side data.  Moreover,
+the course grade updates that occur during calls to this API are synchronous - the entire update operation
+is completed before a response is given to the client.
+
+For decisions made about the implementation of this API, see:
+https://github.com/edx/edx-platform/blob/master/lms/djangoapps/grades/docs/decisions/0001-gradebook-api.rst
+
+Decision
+========
+
+The Gradebook front-end will post data about a single subsection and user in a single request
+to the ``bulk-update`` API.  That is, we currently need only the "update" aspect of this
+endpoint, and not the "bulk" aspect, for satisfying the requirements of the current UX.
+
+Status
+======
+
+Accepted (circa December 2018)
+
+Consequences
+============
+
+This is a scenario in which the implementation of the API is coupled to the
+UX that depends on the API.  Because the course grade update is synchronous, it means
+the API response can contain the updated subsection and course grade data.  Because
+a response from the API contains this data, the UI can operate in a very familiar way:
+
+- A user clicks a button to submit a request with grade update data to the update endpoint.
+- On the server, the subsection and course grades are modified.
+- In the meantime, the client-side user looks at a spinner.
+- A response is returned with updated data and the spinner goes away.
+- Updated data is displayed to the user, along with a message indicative of the update.
+
+If the update becomes asynchronous, the user experience outlined above has to change.
+Because a single call to this endpoint updates grades data for only a single user,
+the endpoint does not necessarily have to utilize an asynchronous operation at this time.

package-lock.json

@@ -10469,14 +10469,12 @@
         "balanced-match": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
           "dev": true,
-          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -10496,8 +10494,7 @@
         "concat-map": {
           "version": "0.0.1",
           "bundled": true,
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "console-control-strings": {
           "version": "1.1.0",
@@ -10645,7 +10642,6 @@
           "version": "3.0.4",
           "bundled": true,
           "dev": true,
-          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }

src/components/Gradebook/index.jsx

@@ -176,7 +176,7 @@ export default class Gradebook extends React.Component {
     return 'Tracks';
   };
 
-  roundGrade = percent => parseFloat(percent.toFixed(DECIMAL_PRECISION));
+  roundGrade = percent => parseFloat((percent || 0).toFixed(DECIMAL_PRECISION));
 
   formatter = {
     percent: (entries, areGradesFrozen) => entries.map((entry) => {