title: chart bars not showing
body: <p>am trying to display a chart using plotly in django project, the chart appears fine in the page, yet i can't see the bars even though data exist in the database. please help</p>
  <p>in views.py</p>
  <pre><code>import pandas as pd
  from plotly.offline import plot
  import plotly.express as px
  
  def viewReport(request):
      attendance = Attendance.objects.all()
      graph_data = [
          {
              'Student': x.student_id,
              'Start': x.date,
              'Finish': x.date,
              'Course': x.course_id
          } for x in attendance
      ]
      graph_frame = pd.DataFrame(graph_data)
      figure = px.timeline(
          graph_frame, x_start=&quot;Start&quot;, x_end=&quot;Finish&quot;, y=&quot;Student&quot;, color=&quot;Course&quot;
      )
      figure.update_yaxes(autorange=&quot;reversed&quot;)
      gantt_plot = plot(figure, output_type=&quot;div&quot;)
  
      # print(attendance)
      attendfilter = AttendanceFilter(request.GET, queryset=attendance)
      attendance = attendfilter.qs
      context = {'attendance': attendance, 'attendfilter': attendfilter, 'gantt_plot':gantt_plot}
      return render(request, 'LogInApp/ViewReport.html', context)
  </code></pre>
  <p>model.py, the model am retrieving data from</p>
  <pre><code>class Attendance(models.Model):
      ATTENDANCE = (
          ('absent', 'Absent'),
          ('present', 'Present')
      )
      student_id = models.CharField(max_length=100, null=True)
      course_id = models.CharField(max_length=100, null=True)
      date = models.DateField(auto_now_add=True, null=True)
      time = models.TimeField(auto_now_add=True, null=True)
      #week_num = models.CharField(max_length=2, blank=True)
      attendanceState = models.CharField(max_length=20, null=True,choices=ATTENDANCE)
  
      def __str__(self):
          return '{}'.format(self.student_id)
  </code></pre>
  <p>viewattendance.html</p>
  <pre><code>                        {% block content%}
                          &lt;div&gt;
                              {% autoescape off %}
                                  {{ gantt_plot }}
                              {% endautoescape%}
                          &lt;/div&gt;
                          {% endblock content%}
                      &lt;/div&gt;
  </code></pre>