Add code to check if there is existing data before executing a bootstrap setup

apps/bootstrap/classes.py

@@ -1,5 +1,9 @@
 from __future__ import absolute_import
 
+from django.db import models
+
+from .exceptions import ExistingData
+
 
 class Cleanup(object):
     """
@@ -25,6 +29,13 @@ class BootstrapModel(object):
     """
     _registry = {}
 
+    @classmethod
+    def check_for_data(cls):
+        for model in cls.get_all():
+            model_instance = models.get_model(model.app_name, model.model_name)
+            if model_instance.objects.all().count():
+                raise ExistingData
+
     @classmethod
     def get_all(cls):
         return cls._registry.values()

apps/bootstrap/exceptions.py

@@ -0,0 +1,10 @@
+from __future__ import absolute_import
+
+
+class ExistingData(Exception):
+    """
+    Raised when an attempt to execute a bootstrap setup is made and there is
+    existing data that would be corrupted or damaged by the loading the 
+    bootstrap's fixture
+    """
+    pass

apps/bootstrap/models.py

@@ -10,6 +10,7 @@ from django.core import management
 from .literals import (FIXTURE_TYPES_CHOICES, FIXTURE_FILE_TYPE,
     FIXTURE_TYPE_PK_NULLIFIER, COMMAND_LOADDATA)
 from .managers import BootstrapSetupManager
+from .classes import BootstrapModel
 
 
 class BootstrapSetup(models.Model):
@@ -30,6 +31,7 @@ class BootstrapSetup(models.Model):
         return FIXTURE_FILE_TYPE[self.type]
 
     def execute(self):
+        BootstrapModel.check_for_data()
         handle, filepath = tempfile.mkstemp()
         # Just need the filepath, close the file description
         os.close(handle)

apps/bootstrap/views.py

@@ -16,6 +16,7 @@ from .permissions import (PERMISSION_BOOTSTRAP_VIEW, PERMISSION_BOOTSTRAP_CREATE
     PERMISSION_BOOTSTRAP_EXECUTE, PERMISSION_NUKE_DATABASE, PERMISSION_BOOTSTRAP_DUMP)
 from .icons import icon_bootstrap_setup_execute, icon_nuke_database, icon_bootstrap_setup_delete
 from .forms import BootstrapSetupForm, BootstrapSetupForm_view, BootstrapSetupForm_dump
+from .exceptions import ExistingData
 
 
 def bootstrap_setup_list(request):
@@ -155,6 +156,8 @@ def bootstrap_setup_execute(request, bootstrap_setup_pk):
     if request.method == 'POST':
         try:
             bootstrap_setup.execute()
+        except ExistingData:
+            messages.error(request, _(u'Cannot execute bootstrap setup, there is existing data.  Erase database and try again.'))
         except Exception, exc:
             messages.error(request, _(u'Error executing bootstrap setup; %s') % exc)
         else: