chore: refactor instance creation view

dash/utils.py

@@ -0,0 +1,54 @@
+# Copyright © 2022 Aravinth Manivannan <realaravinth@batsense.net>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+from enum import Enum, unique
+
+from django.contrib.auth.models import User
+
+from .models import Instance, InstanceConfiguration
+
+
+@unique
+class VmErrors(Enum):
+    NAME_EXISTS = "Instance name exists, please try again with a different name"
+    NO_CONFIG = "Configuration doesn't exist, please try again."
+
+    def __str__(self) -> str:
+        return self.name
+
+
+class VmException(Exception):
+    error: str
+    code: VmErrors
+
+    def __init__(self, code: VmErrors):
+        self.error = str(code)
+        self.code = code
+
+
+def create_instance(vm_name: str, configuration_name: str, user: User) -> Instance:
+    """
+    Create instance view
+    """
+
+    if Instance.objects.filter(name=vm_name).exists():
+        raise VmException(code=VmErrors.NAME_EXISTS)
+
+    if not InstanceConfiguration.objects.filter(name=configuration_name).exists():
+        raise VmException(code=VmErrors.NO_CONFIG)
+
+    configuration = InstanceConfiguration.objects.get(name=configuration_name)
+    instance = Instance(name=vm_name, configuration_id=configuration, owned_by=user)
+    instance.save()
+    return instance

dash/views.py

@@ -21,10 +21,11 @@ from django.http import HttpResponse
 from django.views.decorators.csrf import csrf_protect
 from django.urls import reverse
 
-from .models import Instance, InstanceConfiguration
-
 from accounts.decorators import confirm_access
 
+from .models import Instance, InstanceConfiguration
+from .utils import create_instance as create_instance_util, VmErrors, VmException
+
 
 def default_ctx(title: str, username: str):
     """
@@ -73,32 +74,25 @@ def create_instance(request):
         return render(request, "dash/instances/new/index.html", context=ctx)
 
     name = request.POST["name"]
-    if Instance.objects.filter(name=name).exists():
-        ctx = get_ctx()
-        ctx["error"] = {
-            "title": "Can't create instance",
-            "reason": "Instance name exists, please try again with a different name",
-        }
-        print(ctx["error"]["reason"])
-        return render(request, "dash/instances/new/index.html", status=400, context=ctx)
-
     configuration = request.POST["configuration"]
-    if not InstanceConfiguration.objects.filter(name=configuration).exists():
+    try:
+        instance = create_instance_util(
+            vm_name=name, configuration_name=configuration, user=request.user
+        )
+        return redirect(reverse("billing.invoice.generate", args=(instance.name,)))
+    except VmException as e:
         ctx = get_ctx()
+        if e.code == VmErrors.NAME_EXISTS:
+            reason = ("Instance name exists, please try again with a different name",)
+        elif e.code == VmErrors.NO_CONFIG:
+            reason = "Configuration doesn't exist, please try again."
+
         ctx["error"] = {
             "title": "Can't create instance",
-            "reason": "Configuration doesn't exist, please try again.",
+            "reason": reason,
         }
-        print(ctx["error"]["reason"])
         return render(request, "dash/instances/new/index.html", status=400, context=ctx)
 
-    configuration = get_object_or_404(InstanceConfiguration, name=configuration)
-    instance = Instance(
-        name=name, configuration_id=configuration, owned_by=request.user
-    )
-    instance.save()
-    return redirect(reverse("billing.invoice.generate", args=(instance.name,)))
-
 
 @login_required
 def list_instances(request):