Display empty previous data point on trend line when only one data point exists.

analytics_dashboard/courses/presenters.py

@@ -52,24 +52,36 @@ class CourseEngagementPresenter(BasePresenter):
 
         return activities
 
+    def _build_trend_week(self, trend_types, week_ending, api_trend):
+        trend_week = {'weekEnding': week_ending.isoformat()}
+        for trend_type in trend_types:
+            if trend_type in api_trend:
+                trend_week[trend_type] = api_trend[trend_type] or 0
+            else:
+                trend_week[trend_type] = 0
+        return trend_week
+
     def _build_trend(self, api_trends):
         """
         Format activity trends for specified date range and return results with
         zeros filled in for all activities.
         """
         trend_types = self.get_activity_types()
+        trends = []
+
+        # add zeros for the week prior if we only have a single point (prevents just a single point in the chart)
+        if len(api_trends) == 1:
+            interval_end = self.parse_api_datetime(api_trends[0]['interval_end'])
+            week_ending = interval_end.date() - datetime.timedelta(days=8)
+            trends.append(self._build_trend_week(trend_types, week_ending, {}))
 
         # fill in gaps in activity with zero for display (api doesn't return
         # the field if no data exists for it, so we fill in the zeros here)
-        trends = []
         for datum in api_trends:
             # convert end of interval to ending day of week
             interval_end = self.parse_api_datetime(datum['interval_end'])
             week_ending = interval_end.date() - datetime.timedelta(days=1)
-            trend_week = {'weekEnding': week_ending.isoformat()}
-            for trend_type in trend_types:
-                trend_week[trend_type] = datum[trend_type] or 0
-            trends.append(trend_week)
+            trends.append(self._build_trend_week(trend_types, week_ending, datum))
 
         return trends
 
@@ -116,8 +128,18 @@ class CourseEnrollmentPresenter(BasePresenter):
         now = datetime.datetime.utcnow().strftime(Client.DATE_FORMAT)
         trends = self.course.enrollment(start_date=None, end_date=now)
         summary = self._build_summary(trends)
+
+        # add zero for the day prior (prevents just a single point in the chart)
+        if len(trends) == 1:
+            trends.insert(0, self._build_empty_trend(self.parse_api_date(trends[0]['date'])))
+
         return summary, trends
 
+    def _build_empty_trend(self, day):
+        day = day - datetime.timedelta(days=1)
+        trend = {'date': day.isoformat(), 'count': 0}
+        return trend
+
     def get_geography_data(self):
         """
         Returns a list of course geography data and the updated date (ex. 2014-1-31).

analytics_dashboard/courses/tests/test_presenters.py

@@ -6,7 +6,8 @@ from django.test import TestCase
 
 import analyticsclient.constants.activity_type as AT
 from courses.presenters import CourseEngagementPresenter, CourseEnrollmentPresenter, BasePresenter
-from courses.tests.utils import get_mock_enrollment_data, get_mock_enrollment_summary, \
+from courses.tests.utils import get_mock_enrollment_data, get_mock_presenter_enrollment_data_small, \
+    get_mock_enrollment_summary, get_mock_presenter_enrollment_summary_small, \
     get_mock_api_enrollment_geography_data, get_mock_presenter_enrollment_geography_data, \
     get_mock_api_enrollment_geography_data_limited, get_mock_presenter_enrollment_geography_data_limited, \
     mock_course_activity, CREATED_DATETIME
@@ -39,12 +40,24 @@ class CourseEngagementPresenterTests(TestCase):
 
         return trends
 
-    def assertSummaryAndTrendsValid(self, include_forum_activity):
+    def get_expected_trends_small(self, include_forum_data):
+        trends = self.get_expected_trends(include_forum_data)
+        trends[0].update({
+            AT.ANY: 0,
+            AT.ATTEMPTED_PROBLEM: 0,
+            AT.PLAYED_VIDEO: 0
+        })
+
+        if include_forum_data:
+            trends[0][AT.POSTED_FORUM] = 0
+
+        return trends
+
+    def assertSummaryAndTrendsValid(self, include_forum_activity, expected_trends):
         switch, _created = Switch.objects.get_or_create(name='show_engagement_forum_activity')
         switch.active = include_forum_activity
         switch.save()
 
-        expected_trends = self.get_expected_trends(include_forum_activity)
         summary, trends = self.presenter.get_summary_and_trend_data()
 
         # Validate the trends
@@ -66,8 +79,16 @@ class CourseEngagementPresenterTests(TestCase):
 
     @mock.patch('analyticsclient.course.Course.activity', mock.Mock(side_effect=mock_course_activity))
     def test_get_summary_and_trend_data(self):
-        self.assertSummaryAndTrendsValid(False)
-        self.assertSummaryAndTrendsValid(True)
+        self.assertSummaryAndTrendsValid(False, self.get_expected_trends(False))
+        self.assertSummaryAndTrendsValid(True, self.get_expected_trends(True))
+
+    @mock.patch('analyticsclient.course.Course.activity')
+    def test_get_summary_and_trend_data_small(self, mock_activity):
+        api_trend = [mock_course_activity()[-1]]
+        mock_activity.return_value = api_trend
+
+        self.assertSummaryAndTrendsValid(False, self.get_expected_trends_small(False))
+        self.assertSummaryAndTrendsValid(True, self.get_expected_trends_small(True))
 
 
 class BasePresenterTests(TestCase):
@@ -119,6 +140,15 @@ class CourseEnrollmentPresenterTests(TestCase):
         self.assertListEqual(actual_trend, expected_trend)
 
     @mock.patch('analyticsclient.course.Course.enrollment')
+    def test_get_summary_and_trend_data_small(self, mock_enrollment):
+        api_trend = [get_mock_enrollment_data(self.course_id)[-1]]
+        mock_enrollment.return_value = api_trend
+
+        actual_summary, actual_trend = self.presenter.get_summary_and_trend_data()
+        self.assertDictEqual(actual_summary, get_mock_presenter_enrollment_summary_small())
+        self.assertListEqual(actual_trend, get_mock_presenter_enrollment_data_small(self.course_id))
+
+    @mock.patch('analyticsclient.course.Course.enrollment')
     def test_get_geography_data(self, mock_enrollment):
         # test with a full set of countries
         mock_data = get_mock_api_enrollment_geography_data(self.course_id)

analytics_dashboard/courses/tests/utils.py

@@ -42,6 +42,24 @@ def get_mock_enrollment_summary_and_trend(course_id):
     return get_mock_enrollment_summary(), get_mock_enrollment_data(course_id)
 
 
+def get_mock_presenter_enrollment_data_small(course_id):
+    single_enrollment = get_mock_enrollment_data(course_id)[-1]
+    empty_enrollment = {
+        'count': 0,
+        'date': '2014-01-30'
+    }
+
+    return [empty_enrollment, single_enrollment]
+
+
+def get_mock_presenter_enrollment_summary_small():
+    return {
+        'last_updated': CREATED_DATETIME,
+        'current_enrollment': 30,
+        'enrollment_change_last_7_days': None,
+    }
+
+
 def get_mock_api_enrollment_geography_data(course_id):
     data = []
     items = ((u'USA', u'United States', 500), (None, UNKNOWN_COUNTRY_CODE, 300),

analytics_dashboard/static/js/views/trends-view.js

@@ -18,9 +18,9 @@ define(['bootstrap', 'd3', 'jquery', 'moment', 'nvd3', 'underscore', 'views/attr
              */
             assembleTrendData: function () {
                 var self = this,
-                    combinedTrends,
                     data = self.model.get(self.options.modelAttribute),
-                    trendOptions = self.options.trends;
+                    trendOptions = self.options.trends,
+                    combinedTrends;
 
                 // parse and format the data for nvd3
                 combinedTrends = _(trendOptions).map(function (trendOption) {
@@ -68,9 +68,6 @@ define(['bootstrap', 'd3', 'jquery', 'moment', 'nvd3', 'underscore', 'views/attr
                 // Remove the grid lines
                 canvas.selectAll('.nvd3 .nv-axis line').remove();
 
-                // Remove max value from the X-axis
-                canvas.select('.nvd3 .nv-axis.nv-x .nv-axisMaxMin:nth-child(3)').remove();
-
                 // Get the existing X-axis translation and shift it down a few more pixels.
                 axisEl = canvas.select('.nvd3 .nv-axis.nv-x');
                 matches = translateRegex.exec(axisEl.attr('transform'));
@@ -92,11 +89,14 @@ define(['bootstrap', 'd3', 'jquery', 'moment', 'nvd3', 'underscore', 'views/attr
                 AttributeListenerView.prototype.render.call(this);
                 var self = this,
                     canvas = d3.select(self.el),
+                    assembledData = self.assembleTrendData(),
+                    displayExplicitTicksThreshold = 11,
                     chart,
-                    $tooltip;
+                    $tooltip,
+                    xTicks;
 
                 chart = nvd3.models.lineChart()
-                    .margin({top: 1})
+                    .margin({top: 6})// minimize the spacing, but leave enough for point at the top to be shown w/o being clipped
                     .height(300)    // This should be the same as the height set on the chart container in CSS.
                     .showLegend(false)
                     .useInteractiveGuideline(true)
@@ -110,6 +110,16 @@ define(['bootstrap', 'd3', 'jquery', 'moment', 'nvd3', 'underscore', 'views/attr
                         return d[self.options.y.key];
                     });
 
+                // explicitly display tick marks for small numbers of points, otherwise
+                // ticks will be interpolated and dates look to be repeated on the x-axis
+                if(self.model.get(self.options.modelAttribute).length < displayExplicitTicksThreshold) {
+                    // get dates for the explicit ticks -- assuming data isn't sparse
+                    xTicks = _(self.assembleTrendData()[0].values).map(function (data) {
+                        return Date.parse(data[self.options.x.key]);
+                    });
+                    chart.xAxis.tickValues(xTicks);
+                }
+
                 chart.xAxis
                     .tickFormat(function (d) {
                         // date is converted to unix timestamp from our original mm-dd-yyyy format
@@ -139,13 +149,13 @@ define(['bootstrap', 'd3', 'jquery', 'moment', 'nvd3', 'underscore', 'views/attr
                     .append('div')
                     .attr('class', 'line-chart')
                     .append('svg')
-                    .datum(self.assembleTrendData())
+                    .datum(assembledData)
                     .call(chart);
 
                 self.styleChart();
 
                 nvd3.utils.windowResize(chart.update);
-                nv.utils.windowResize(function () {
+                nvd3.utils.windowResize(function () {
                     self.styleChart();
                 });