Add a basic bar chart showing average feeding durations over time.

babybuddy/settings/development.py

@@ -5,6 +5,7 @@ from .base import *
 
 SECRET_KEY = 'CHANGE ME'
 DEBUG = True
+TIME_ZONE = 'America/New_York'
 
 
 # Database

dashboard/templates/dashboard/child_button_group.html

@@ -16,6 +16,7 @@
         <div class="dropdown-menu" aria-labelledby="reports-dropdown">
             <a class="dropdown-item" href="{% url 'reports:report-diaperchange-types-child' object.slug %}">Diaper Change Types</a>
             <a class="dropdown-item" href="{% url 'reports:report-diaperchange-lifetimes-child' object.slug %}">Diaper Lifetimes</a>
+            <a class="dropdown-item" href="{% url 'reports:report-feeding-duration-child' object.slug %}">Feeding Durations (Average)</a>
             <a class="dropdown-item" href="{% url 'reports:report-sleep-pattern-child' object.slug %}">Sleep Pattern</a>
             <a class="dropdown-item" href="{% url 'reports:report-sleep-totals-child' object.slug %}">Sleep Totals</a>
             <a class="dropdown-item" href="{% url 'reports:report-weight-weight-child' object.slug %}">Weight</a>

reports/graphs/__init__.py

@@ -1,5 +1,6 @@
 from .diaperchange_lifetimes import diaperchange_lifetimes  # NOQA
 from .diaperchange_types import diaperchange_types  # NOQA
+from .feeding_duration import feeding_duration  # NOQA
 from .sleep_pattern import sleep_pattern  # NOQA
 from .sleep_totals import sleep_totals  # NOQA
 from .weight_weight import weight_weight  # NOQA

reports/graphs/feeding_duration.py

@@ -0,0 +1,67 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db.models import Count, Sum
+from django.db.models.functions import TruncDate
+
+import plotly.offline as plotly
+import plotly.graph_objs as go
+
+from core.utils import duration_parts
+
+from reports import utils
+
+
+def feeding_duration(instances):
+    """
+    Create a graph showing average duration of feeding instances over time.
+
+    This function originally used the Avg() function from django.db.models but
+    for some reason it was returning None any time the exact count of entries
+    was equal to seven.
+
+    :param instances: a QuerySet of Feeding instances.
+    :returns: a tuple of the the graph's html and javascript.
+    """
+    totals = instances.annotate(date=TruncDate('start')) \
+        .values('date') \
+        .annotate(count=Count('id')) \
+        .annotate(sum=Sum('duration')) \
+        .order_by('-date')
+
+    averages = []
+    for total in totals:
+        averages.append(total['sum']/total['count'])
+
+    trace = go.Bar(
+        name='Average duration',
+        x=list(totals.values_list('date', flat=True)),
+        y=[td.seconds/60 for td in averages],
+        hoverinfo='text',
+        textposition='outside',
+        text=[_duration_string_minutes(td) for td in averages]
+    )
+
+    layout_args = utils.default_graph_layout_options()
+    layout_args['barmode'] = 'stack'
+    layout_args['title'] = '<b>Average Feeding Durations</b>'
+    layout_args['xaxis']['title'] = 'Date'
+    layout_args['xaxis']['rangeselector'] = utils.rangeselector_date()
+    layout_args['yaxis']['title'] = 'Average duration (minutes)'
+
+    fig = go.Figure({
+        'data': [trace],
+        'layout': go.Layout(**layout_args)
+    })
+    output = plotly.plot(fig, output_type='div', include_plotlyjs=False)
+    return utils.split_graph_output(output)
+
+
+def _duration_string_minutes(duration):
+    """
+    Format a "short" duration string with only minutes precision. This is
+    intended to fit better in smaller spaces on a graph.
+    :returns: a string of the form Xm.
+    """
+    h, m, s = duration_parts(duration)
+    return '{}m'.format(m)

reports/templates/reports/feeding_duration.html

@@ -0,0 +1,13 @@
+{% extends 'reports/report_base.html' %}
+
+{% block title %}Average Feeding Durations - {{ object }}{% endblock %}
+
+{% block breadcrumbs %}
+    {{ block.super }}
+    <li class="breadcrumb-item active" aria-current="page">Average Feeding Durations</li>
+{% endblock %}
+
+{% block javascript %}
+    {{ block.super }}
+    {{ javascript|safe }}
+{% endblock %}

reports/tests/tests_views.py

@@ -40,6 +40,9 @@ class ViewsTestCase(TestCase):
         page = self.c.get('{}/changes/types/'.format(base_url))
         self.assertEqual(page.status_code, 200)
 
+        page = self.c.get('{}/feeding/duration/'.format(base_url))
+        self.assertEqual(page.status_code, 200)
+
         page = self.c.get('{}/sleep/pattern/'.format(base_url))
         self.assertEqual(page.status_code, 200)
         page = self.c.get('{}/sleep/totals/'.format(base_url))

reports/urls.py

@@ -13,6 +13,10 @@ urlpatterns = [
         views.DiaperChangeTypesChildReport.as_view(),
         name='report-diaperchange-types-child'),
 
+    url(r'^children/(?P<slug>[^/.]+)/reports/feeding/duration/$',
+        views.FeedingDurationChildReport.as_view(),
+        name='report-feeding-duration-child'),
+
     url(r'^children/(?P<slug>[^/.]+)/reports/sleep/pattern/$',
         views.SleepPatternChildReport.as_view(),
         name='report-sleep-pattern-child'),

reports/views.py

@@ -47,6 +47,30 @@ class DiaperChangeTypesChildReport(PermissionRequiredMixin, DetailView):
         return context
 
 
+class FeedingDurationChildReport(PermissionRequiredMixin, DetailView):
+    """
+    Graph of feeding durations over time.
+    """
+    model = models.Child
+    permission_required = ('core.view_child',)
+    template_name = 'reports/feeding_duration.html'
+
+    def __init__(self):
+        super(FeedingDurationChildReport, self).__init__()
+        self.html = ''
+        self.javascript = ''
+
+    def get_context_data(self, **kwargs):
+        context = super(FeedingDurationChildReport, self).get_context_data(
+            **kwargs)
+        child = context['object']
+        instances = models.Feeding.objects.filter(child=child)
+        if instances:
+            context['html'], context['javascript'] = \
+                graphs.feeding_duration(instances)
+        return context
+
+
 class SleepPatternChildReport(PermissionRequiredMixin, DetailView):
     """
     Graph of sleep pattern comparing sleep to wake times by day.