adds an age property to the demographcis model

.envrc

@@ -0,0 +1,2 @@
+layout python python3.4
+

changelog.md

@@ -1,5 +1,8 @@
 ### 0.14.0 (Major Release)
 
+
+Adds the `age` property to demographics that returns the patient's age.
+
 A User's UserProfile is now automatically created when you create a user in a post save signal.
 
 ### 0.13.1 (Minor Release)

doc/docs/reference/subrecords.md

@@ -224,3 +224,35 @@ fields external_system and external_identifier to allow us to track where
 they come from and how they are referenced by that system.
 
 These fields are then often used in forms to make the data read only
+
+
+### Specific subrecords
+
+#### Demographics
+Opal ships with a demographics model that models personally identifying information for a patient.
+
+This model maps
+
+ - `hospital_number`
+ - `nhs_number`
+ - `surname`
+ - `first_name`
+ - `middle name`
+ - `title`
+ - `date_of_birth`
+ - `marital_status`
+ - `religion`
+ - `date_of_death`
+ - `post_code`
+ - `birth_place`
+ - `ethnicity`
+ - `death_indicator`
+ - `sex`
+
+It also has the properties:
+
+ - `name` - The first name and the surname combined.
+ - `age` - The current age of the patient (today - their date of birth)
+
+
+

opal/models.py

@@ -9,6 +9,7 @@
 import logging
 import random
 import os
+from dateutil.relativedelta import relativedelta
 
 from django.utils import timezone
 from django.db import models, transaction
@@ -1412,8 +1413,25 @@ class Demographics(PatientSubrecord):
 
     @property
     def name(self):
+        """
+        Property that returns the name of the patient constructed from
+        `first_name` and `surname`
+        """
         return '{0} {1}'.format(self.first_name, self.surname)
 
+    @property
+    def age(self):
+        """
+        Property that returns the age of the patient in years
+        or None if `date_of_birth` is not set.
+        """
+        if self.date_of_birth:
+            today = datetime.date.today()
+            return relativedelta(
+                today,
+                self.date_of_birth
+            ).years
+
     class Meta:
         abstract = True
         verbose_name_plural = "Demographics"

opal/tests/test_models.py

@@ -820,6 +820,16 @@ def test_name(self):
                                 middle_name='Obsidian')
         self.assertEqual('Jane Doe', d.name)
 
+    def test_age_no_date_of_birth(self):
+        d = models.Demographics(date_of_birth=None)
+        self.assertIsNone(d.age)
+
+    @patch("opal.models.datetime")
+    def test_age(self, dt):
+        dt.date.today.return_value = datetime.date(2017, 3, 1)
+        d = models.Demographics(date_of_birth=datetime.date(2016, 1, 28))
+        self.assertEqual(d.age, 1)
+
 
 class ExternalSystemTestCase(OpalTestCase):
     def test_get_footer(self):