Enforce that a validated bill has a pdf

- improve data consistence using sql transactions
- make the business logic more explicit in templates

coin/billing/models.py

@@ -7,7 +7,7 @@ import uuid
 import os
 from decimal import Decimal
 
-from django.db import models
+from django.db import models, transaction
 from django.db.models.signals import post_save
 from django.dispatch import receiver
 
@@ -111,15 +111,16 @@ class Invoice(models.Model):
         pdf_file = render_as_pdf('billing/invoice_pdf.html', context)
         self.pdf.save('%s.pdf' % self.number, pdf_file)
 
+    @transaction.atomic
     def validate(self):
         """
         Switch invoice to validate mode. This set to False the draft field
         and generate the pdf
         """
-        if not self.pdf_exists():
-            self.validated = True
-            self.save()
-            self.generate_pdf()
+        self.validated = True
+        self.save()
+        self.generate_pdf()
+        assert self.pdf_exists()
 
     def save(self, *args, **kwargs):
         self.number = Invoice.objects.get_next_invoice_number(self.date)

coin/billing/templates/admin/billing/invoice/change_form.html

@@ -3,7 +3,7 @@
 {% block object-tools-items %}
     {% if not original.validated %}
         <li><a href="{% url 'admin:invoice_validate' id=object_id %}">Valider la facture</a></li>
-    {% elif original.pdf_exists %}
+    {% elif original.validated %}
         <li><a href="{% url 'billing:invoice_pdf' id=object_id %}">Télécharger le PDF</a></li>
     {% endif %}
     {{ block.super }}

coin/billing/templates/billing/invoice.html

@@ -7,7 +7,7 @@
         <p>Émise le {{ invoice.date }}</p>
     </div>
     <div class="large-4 columns">
-        {% if invoice.pdf_exists %}<a href="{% url 'billing:invoice_pdf' id=invoice.number %}" target="_blank" class="button expand"><i class="fa fa-file-pdf-o"></i> Télécharger en PDF</a>{% endif %}
+        {% if invoice.validated %}<a href="{% url 'billing:invoice_pdf' id=invoice.number %}" target="_blank" class="button expand"><i class="fa fa-file-pdf-o"></i> Télécharger en PDF</a>{% endif %}
     </div>
 </div>
 

coin/members/templates/members/invoices.html

@@ -20,7 +20,7 @@
             <td>{{ invoice.date }}</td>
             <td>{{ invoice.amount }}</td>
             <td{% if invoice.amount_remaining_to_pay > 0 %} class="unpaid"{% endif %}>{{ invoice.amount_remaining_to_pay }}</td>
-            <td>{% if invoice.pdf_exists %}<a href="{% url 'billing:invoice_pdf' id=invoice.number %}"><i class="fa fa-file-pdf-o"></i> PDF</a>{% endif %}</td>
+            <td>{% if invoice.validated %}<a href="{% url 'billing:invoice_pdf' id=invoice.number %}"><i class="fa fa-file-pdf-o"></i> PDF</a>{% endif %}</td>
         </tr>
         {% empty %}
         <tr class="placeholder"><td colspan="6">Aucune facture.</td></tr>