Integration of Resource and Record

consumption/migrations/0004_alter_record_options.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.0.2 on 2022-02-25 08:29
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('consumption', '0003_record'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='record',
+            options={'ordering': ['-timestamp'], 'verbose_name': 'Record', 'verbose_name_plural': 'Records'},
+        ),
+    ]

consumption/models/record.py

@@ -39,6 +39,7 @@ class Meta:  # noqa: D106
         app_label = "consumption"
         verbose_name = _("Record")
         verbose_name_plural = _("Records")
+        ordering = ["-timestamp"]
 
     def __str__(self):  # noqa: D105
         return "{}: {} ({}, {})".format(

consumption/templates/consumption/resource_detail.html

@@ -14,4 +14,29 @@ <h2>{{ resource_instance.name }}</h2>
   <p>This resource is tracked for <a href="{% url "consumption:subject-detail" resource_instance.subject.id %}">{{ resource_instance.subject.name }}</a>.</p>
   <p>The unit of this resource is <strong>{{ resource_instance.unit }}</strong></p>
 </div>
+
+<div class="resource-records">
+  <a href="{% url "consumption:record-create" resource_instance.id %}">
+    <button>add Record for this Resource</button>
+  </a>
+  {% if records %}
+  <table>
+    <tr>
+      <th>Date/Time</th>
+      <th>Value</th>
+      <th>Actions</th>
+    </tr>
+    {% for record in records %}
+      <tr>
+        <td>{{ record.timestamp }}</td>
+        <td>{{ record.reading }} {{ resource_instance.unit }}</td>
+        <td>
+          <a href="{% url "consumption:record-update" record.id %}">update</a> |
+          <a href="{% url "consumption:record-delete" record.id %}">delete</a>
+        </td>
+      </tr>
+    {% endfor %}
+  </table>
+  {% endif %}
+</div>
 {% endblock main %}

consumption/urls.py

@@ -66,6 +66,11 @@
     ),
     # Record-related URLs
     path("record/create/", RecordCreateView.as_view(), name="record-create"),
+    path(
+        "record/create/<int:resource_id>/",
+        RecordCreateView.as_view(),
+        name="record-create",
+    ),
     path(
         "record/<int:record_id>/",
         RecordDetailView.as_view(),

consumption/views/record.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: MIT
 
-"""Views related to the :class:`~consumption.models.subject.Subject` model."""
+"""Views related to the :class:`~consumption.models.record.Record` model."""
 
 # Django imports
 from django.contrib.auth.mixins import LoginRequiredMixin
@@ -18,6 +18,15 @@ class RecordCreateView(LoginRequiredMixin, generic.CreateView):
     (as of now), meaning: every (authenticated) user is able to create
     :class:`~consumption.models.record.Record` objects.
 
+    The view supports two different operation modes:
+
+        - create a new
+          :class:`~consumption.models.record.Record` instance *from scratch*;
+        - create a new instance of
+          :class:`~consumption.models.record.Record` with a pre-defined
+          :class:`~consumption.models.resource.Resource` instance to associate
+          the new instance to.
+
     After successfully creating a new instance of
     :class:`~consumption.models.record.Record` the user will be redirected
     to the URL as provided by
@@ -41,6 +50,37 @@ class RecordCreateView(LoginRequiredMixin, generic.CreateView):
     template_name_suffix = "_create"
     """Uses the template ``templates/consumption/record_create.html``."""
 
+    def get_form_kwargs(self):
+        """Provide *initial values* for the form.
+
+        This method implements the two operation modes.
+
+        If a ``resource_id`` is provided as an URL parameter, the referenced
+        :class:`~consumption.models.resource.Resource` instance is provided as
+        initial value while rendering the form (template).
+        """
+        kwargs = super().get_form_kwargs()
+
+        try:
+            kwargs["initial"]["resource"] = self.kwargs["resource_id"]
+        except KeyError:
+            pass
+
+        return kwargs
+
+    def get_success_url(self):  # pragma: nocover
+        """Determine the URL for redirecting after successful deletion.
+
+        This has to be done dynamically with a method instead of statically
+        with the ``success_url`` attribute, because the user should be
+        redirected to the *parent*
+        :class:`~consumption.models.resource.Resource` instance.
+        """
+        resource = self.object.resource
+        return reverse_lazy(
+            "consumption:resource-detail", kwargs={"resource_id": resource.id}
+        )
+
 
 class RecordDetailView(generic.DetailView):
     """Provide the details of :class:`~consumption.models.record.Record` instances.
@@ -120,7 +160,7 @@ class RecordDeleteView(LoginRequiredMixin, generic.DeleteView):
     pk_url_kwarg = "record_id"
     """The keyword argument as provided in :mod:`consumption.urls`."""
 
-    def get_success_url(self):
+    def get_success_url(self):  # pragma: nocover
         """Determine the URL for redirecting after successful deletion.
 
         This has to be done dynamically with a method instead of statically

consumption/views/resource.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: MIT
 
-"""Views related to the :class:`~consumption.models.subject.Subject` model."""
+"""Views related to the :class:`~consumption.models.resource.Resource` model."""
 
 # Django imports
 from django.contrib.auth.mixins import LoginRequiredMixin
@@ -57,6 +57,53 @@ class ResourceDetailView(generic.DetailView):
     pk_url_kwarg = "resource_id"
     """The keyword argument as provided in :mod:`consumption.urls`."""
 
+    def get_queryset(self):
+        """Optimize database queries.
+
+        Override to the default implementation of ``get_queryset()`` to
+        select the referenced instance of
+        :class:`~consumption.models.subject.Subject` (referenced by
+        :attr:`Resource.subject <consumption.models.resource.Resource.subject>`)
+        and prefetch all associated instances of
+        :class:`~consumption.models.record.Record` (that is: all instances of
+        :class:`~consumption.models.record.Record` that reference this instance
+        of :class:`~consumption.models.resource.Resource` by their
+        :attr:`~consumption.models.record.Record.resource` attribute).
+
+        Warning
+        -------
+        This method does only modify / extend / prepare the actual database
+        queries, it does not provide the resulting objects in the rendering
+        context for the template (actually the
+        :class:`~consumption.models.subject.Subject` instance will be easily
+        accessible by using ``resource_instance.subject`` in the template).
+
+        See
+        :meth:`~consumption.views.resource.ResourceDetailView.get_context_data`
+        for that.
+        """
+        return (
+            super()
+            .get_queryset()
+            .select_related("subject")
+            .prefetch_related("record_set")
+        )
+
+    def get_context_data(self, **kwargs):
+        """Add a list of related ``Record`` instances to the context.
+
+        :meth:`~consumption.views.resource.ResourceDetailView.get_queryset`
+        will optimize the database access, but the list of
+        :class:`~consumption.models.record.Record` instances must still be
+        added to the rendering context.
+        """
+        context = super().get_context_data(**kwargs)
+
+        if self.object:
+            context["records"] = self.object.record_set.all()
+
+        return context
+
 
 class ResourceUpdateView(LoginRequiredMixin, generic.UpdateView):
     """Generic class-based view to update :class:`~consumption.models.resource.Resource` objects.
@@ -120,7 +167,7 @@ class ResourceDeleteView(LoginRequiredMixin, generic.DeleteView):
     pk_url_kwarg = "resource_id"
     """The keyword argument as provided in :mod:`consumption.urls`."""
 
-    def get_success_url(self):
+    def get_success_url(self):  # pragma: nocover
         """Determine the URL for redirecting after successful deletion.
 
         This has to be done dynamically with a method instead of statically