Make Weight use simpler view pattern

Author: Themitchell

features/weight.feature

@@ -1,3 +1,4 @@
+@Weight
 Feature: Weight page
   Scenario: The page is accessible
     Given I am logged in
@@ -62,8 +63,17 @@ Feature: Weight page
     And I see "/weight?change=True" as a link to change "Weight" under "About you"
     When I click the link to change "Weight" under "About you"
     Then I am on "/weight?change=True"
+    And I see "70.0" filled in for "Kilograms"
     When I click "Switch to stone and pounds"
     And I fill in and submit my weight with "5" stone and "10" pounds
     Then I am on "/check-your-answers"
     And I see "5 stone 10 pounds" as a response to "Weight" under "About you"
+    When I click the link to change "Weight" under "About you"
+    Then I am on "/weight?change=True"
+    And I see "5" filled in for "Stone"
+    And I see "10" filled in for "Pounds"
+    When I click "Switch to kilograms"
+    And I fill in and submit my weight with "70.4"
+    Then I am on "/check-your-answers"
+    And I see "70.4 kg" as a response to "Weight" under "About you"
 

lung_cancer_screening/questions/tests/unit/forms/test_imperial_weight_form.py

@@ -1,10 +1,11 @@
-from django.test import TestCase
+from django.test import TestCase, tag
 
 from ...factories.response_set_factory import ResponseSetFactory
 from ....models.weight_response import WeightResponse
 from ....forms.imperial_weight_form import ImperialWeightForm
 
 
+@tag("Weight")
 class TestImperialWeightForm(TestCase):
     def setUp(self):
         self.response_set = ResponseSetFactory()

lung_cancer_screening/questions/tests/unit/forms/test_metric_weight_form.py

@@ -1,10 +1,11 @@
-from django.test import TestCase
+from django.test import TestCase, tag
 
 from ...factories.response_set_factory import ResponseSetFactory
 from ....models.weight_response import WeightResponse
 from ....forms.metric_weight_form import MetricWeightForm
 
 
+@tag("Weight")
 class TestMetricWeightForm(TestCase):
     def setUp(self):
         self.response_set = ResponseSetFactory()

lung_cancer_screening/questions/tests/unit/models/test_weight_response.py

@@ -1,11 +1,12 @@
-from django.test import TestCase
+from django.test import TestCase, tag
 
 from ...factories.response_set_factory import ResponseSetFactory
 from ...factories.weight_response_factory import WeightResponseFactory
 
 from ....models.weight_response import WeightResponse
 
 
+@tag("Weight")
 class TestWeightResponse(TestCase):
     def setUp(self):
         self.response_set = ResponseSetFactory()

lung_cancer_screening/questions/tests/unit/views/test_weight.py

@@ -1,4 +1,4 @@
-from django.test import TestCase
+from django.test import TestCase, tag
 from django.urls import reverse
 from dateutil.relativedelta import relativedelta
 from django.utils import timezone
@@ -7,6 +7,7 @@
 from lung_cancer_screening.questions.models.weight_response import WeightResponse
 
 
+@tag("Weight")
 class TestGetWeight(TestCase):
     def setUp(self):
         self.user = login_user(self.client)
@@ -72,6 +73,7 @@ def test_get_renders_the_imperial_form_if_specified(self):
         self.assertContains(response, "Pounds")
 
 
+@tag("Weight")
 class TestPostWeight(TestCase):
     def setUp(self):
         self.user = login_user(self.client)

lung_cancer_screening/questions/views/weight.py

@@ -1,4 +1,4 @@
-from django.shortcuts import render
+from django.urls import reverse_lazy
 
 from .question_base_view import QuestionBaseView
 from lung_cancer_screening.questions.forms.metric_weight_form import (
@@ -11,69 +11,27 @@
 
 
 class WeightView(QuestionBaseView):
-    def get(self, request):
-        response, _ = WeightResponse.objects.get_or_build(
-            response_set=request.response_set
+    template_name = "weight.jinja"
+    model = WeightResponse
+    success_url = reverse_lazy("questions:sex_at_birth")
+    back_link_url = reverse_lazy("questions:height")
+
+    def get_form_class(self):
+        unit = self.get_unit()
+        return ImperialWeightForm if unit == "imperial" else MetricWeightForm
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        unit = self.get_unit()
+        context["unit"] = unit
+        context["switch_to_unit"] = (
+            "metric" if unit == "imperial" else "imperial"
         )
+        return context
 
-        unit = self.get_unit(request, response)
-
-        form_klass = (
-            ImperialWeightForm if unit == "imperial" else MetricWeightForm
-        )
-
-        return render(
-            request,
-            "weight.jinja",
-            {
-                "form": form_klass(instance=response),
-                "unit": unit,
-                "switch_to_unit": (
-                    "metric" if unit == "imperial" else "imperial"
-                )
-            }
-        )
-
-    def post(self, request):
-        response, _ = WeightResponse.objects.get_or_build(
-            response_set=request.response_set
-        )
-        unit = self.get_unit(request, response)
-
-
-        form_klass = (
-            ImperialWeightForm if unit == "imperial" else MetricWeightForm
-        )
-
-        form = form_klass(
-            instance=response,
-            data=request.POST
-        )
-
-        if form.is_valid():
-            form.save()
-            return self.redirect_to_response_or_next_question(
-                request,
-                "questions:sex_at_birth"
-            )
-        else:
-            return render(
-                request,
-                "weight.jinja",
-                {
-                    "form": form,
-                    "unit": unit,
-                    "switch_to_unit": (
-                        "metric" if unit == "imperial" else "imperial"
-                    )
-                },
-                status=422
-            )
-
-    def get_unit(self, request, response):
-        unit = request.GET.get('unit')
-
+    def get_unit(self):
+        unit = self.request.GET.get('unit')
+        response = self.get_object()
         if response.imperial and unit != "metric":
             unit = "imperial"
-
         return unit