more constraints added at form and model level

3 files changed, 72 insertions, 2 deletions

diff --git a/ctrack/register/forms.py b/ctrack/register/forms.py
index 1d46c36..1c69bcd 100644
--- a/ctrack/register/forms.py
+++ b/ctrack/register/forms.py
@@ -1,6 +1,7 @@
 from crispy_forms.helper import FormHelper
 from crispy_forms.layout import Button, ButtonHolder, Layout, Submit, Hidden, Field
 from django import forms
+from django.core.exceptions import ValidationError
 from django.shortcuts import get_object_or_404
 from django.urls import reverse
 
@@ -60,6 +61,16 @@ class CAFSingleDateEventForm(forms.ModelForm):
 
 
 class CAFTwinDateEventForm(forms.ModelForm):
+    # This constraint in the form prevents two such objects being created
+    # for the same CAF with the same start date, which does not make sense.
+    def clean_start_date(self):
+        data = self.cleaned_data["start_date"]
+        caf = self.cleaned_data["related_caf"]
+        existing_obj = CAFTwinDateEvent.objects.filter(start_date=data).filter(related_caf=caf).first()
+        if existing_obj:
+            raise ValidationError("You cannot have two CAF events starting on the same date.")
+        return data
+
     class Meta:
         model = CAFTwinDateEvent
         fields = [
diff --git a/ctrack/register/models.py b/ctrack/register/models.py
index 9e0516e..03a7d80 100644
--- a/ctrack/register/models.py
+++ b/ctrack/register/models.py
@@ -5,7 +5,7 @@ from typing import Optional, Dict
 
 from django.contrib.auth import get_user_model
 from django.db import models
-from django.db.models import Q
+from django.db.models import Q, F
 
 from ctrack.caf.models import CAF
 from ctrack.organisations.models import Person
@@ -170,10 +170,22 @@ class CAFTwinDateEvent(EventBase, CAFMixin, TwinDateMixin):
         blank=False, max_length=50, choices=AVAILABLE_TYPES
     )
 
+    def __repr__(self):
+        return "".join(["CAFTwinDateEvent(", self.type_descriptor, ")"])
 
-# OLD CODE BELOW
+    def __str__(self):
+        return f"CAFTwinDateEvent({self.type_descriptor}) starting {self.start_date}"
+
+    class Meta:
+        constraints = [
+            models.CheckConstraint(
+                name="end_date_cannot_precede_start_date",
+                check=~Q(end_date__lt=F("start_date")),
+            )
+        ]
 
 
+# OLD CODE BELOW
 class EngagementType(models.Model):
     """
     Examples here are Phone, Email, Letter, Site visit, Meeting, Audit, Inspection, etc.
diff --git a/ctrack/register/tests/test_forms.py b/ctrack/register/tests/test_forms.py
index f1b8630..401ed2f 100644
--- a/ctrack/register/tests/test_forms.py
+++ b/ctrack/register/tests/test_forms.py
@@ -154,3 +154,50 @@ def test_caf_twin_date_event(user, caf):
         user=user,
     )
     assert form.is_valid()
+
+
+@pytest.mark.parametrize("allowed_type", ["CAF_PEER_REVIEW_PERIOD", "CAF_VALIDATION_PERIOD"])
+def test_cannot_create_twin_date_event_for_caf_whose_end_date_is_open(allowed_type, user, caf):
+    e1 = CAFTwinDateEventForm(
+        {
+            "type_descriptor": allowed_type,
+            "related_caf": caf,
+            "short_description": "caf peer review for x company",
+            "start_date": "2020-10-10",
+            "comments": "nice comments for this event",
+        },
+        user=user,
+    )
+    e2 = CAFTwinDateEventForm(
+        {
+            "type_descriptor": allowed_type,
+            "related_caf": caf,
+            "short_description": "caf peer review for x company",
+            "start_date": "2020-10-10",
+            "comments": "nice comments for this event",
+        },
+        user=user,
+    )
+    assert e1.is_valid()
+    e1.save()
+    assert e2.is_valid() is False
+    assert e2.errors == {
+        "start_date": ["You cannot have two CAF events starting on the same date."]
+    }
+
+
+@pytest.mark.parametrize("allowed_type", ["CAF_PEER_REVIEW_PERIOD", "CAF_VALIDATION_PERIOD"])
+def test_cannot_create_twin_date_event_where_end_date_precedes_start(allowed_type, user, caf):
+    "This one is done with a database integrity check instead of a form validation"
+    with pytest.raises(IntegrityError):
+        CAFTwinDateEventForm(
+            {
+                "type_descriptor": allowed_type,
+                "related_caf": caf,
+                "short_description": "caf peer review for x company",
+                "start_date": "2020-10-10",
+                "end_date": "2020-10-09",
+                "comments": "nice comments for this event",
+            },
+            user=user,
+        ).save()