Rename module async to tasks (#994)

Fixes #993

src/pretix/base/views/tasks.py

@@ -0,0 +1,139 @@
+import logging
+
+import celery.exceptions
+from celery.result import AsyncResult
+from django.conf import settings
+from django.contrib import messages
+from django.http import JsonResponse
+from django.shortcuts import redirect, render
+from django.utils.translation import ugettext as _
+
+from pretix.celery_app import app
+
+logger = logging.getLogger('pretix.base.tasks')
+
+
+class AsyncAction:
+    task = None
+    success_url = None
+    error_url = None
+    known_errortypes = []
+
+    def do(self, *args, **kwargs):
+        if not isinstance(self.task, app.Task):
+            raise TypeError('Method has no task attached')
+
+        res = self.task.apply_async(args=args, kwargs=kwargs)
+
+        if 'ajax' in self.request.GET or 'ajax' in self.request.POST:
+            data = self._return_ajax_result(res)
+            data['check_url'] = self.get_check_url(res.id, True)
+            return JsonResponse(data)
+        else:
+            if res.ready():
+                if res.successful() and not isinstance(res.info, Exception):
+                    return self.success(res.info)
+                else:
+                    return self.error(res.info)
+            return redirect(self.get_check_url(res.id, False))
+
+    def get_success_url(self, value):
+        return self.success_url
+
+    def get_error_url(self):
+        return self.error_url
+
+    def get_check_url(self, task_id, ajax):
+        return self.request.path + '?async_id=%s' % task_id + ('&ajax=1' if ajax else '')
+
+    def get(self, request, *args, **kwargs):
+        if 'async_id' in request.GET and settings.HAS_CELERY:
+            return self.get_result(request)
+        return self.http_method_not_allowed(request)
+
+    def _ajax_response_data(self):
+        return {}
+
+    def _return_ajax_result(self, res, timeout=.5):
+        if not res.ready():
+            try:
+                res.get(timeout=timeout, propagate=False)
+            except celery.exceptions.TimeoutError:
+                pass
+
+        ready = res.ready()
+        data = self._ajax_response_data()
+        data.update({
+            'async_id': res.id,
+            'ready': ready
+        })
+        if ready:
+            if res.successful() and not isinstance(res.info, Exception):
+                smes = self.get_success_message(res.info)
+                if smes:
+                    messages.success(self.request, smes)
+                # TODO: Do not store message if the ajax client states that it will not redirect
+                # but handle the mssage itself
+                data.update({
+                    'redirect': self.get_success_url(res.info),
+                    'success': True,
+                    'message': str(self.get_success_message(res.info))
+                })
+            else:
+                messages.error(self.request, self.get_error_message(res.info))
+                # TODO: Do not store message if the ajax client states that it will not redirect
+                # but handle the mssage itself
+                data.update({
+                    'redirect': self.get_error_url(),
+                    'success': False,
+                    'message': str(self.get_error_message(res.info))
+                })
+        return data
+
+    def get_result(self, request):
+        res = AsyncResult(request.GET.get('async_id'))
+        if 'ajax' in self.request.GET:
+            return JsonResponse(self._return_ajax_result(res, timeout=0.25))
+        else:
+            if res.ready():
+                if res.successful() and not isinstance(res.info, Exception):
+                    return self.success(res.info)
+                else:
+                    return self.error(res.info)
+            return render(request, 'pretixpresale/waiting.html')
+
+    def success(self, value):
+        smes = self.get_success_message(value)
+        if smes:
+            messages.success(self.request, smes)
+        if "ajax" in self.request.POST or "ajax" in self.request.GET:
+            return JsonResponse({
+                'ready': True,
+                'success': True,
+                'redirect': self.get_success_url(value),
+                'message': str(self.get_success_message(value))
+            })
+        return redirect(self.get_success_url(value))
+
+    def error(self, exception):
+        messages.error(self.request, self.get_error_message(exception))
+        if "ajax" in self.request.POST or "ajax" in self.request.GET:
+            return JsonResponse({
+                'ready': True,
+                'success': False,
+                'redirect': self.get_error_url(),
+                'message': str(self.get_error_message(exception))
+            })
+        return redirect(self.get_error_url())
+
+    def get_error_message(self, exception):
+        if isinstance(exception, dict) and exception['exc_type'] in self.known_errortypes:
+            return exception['exc_message']
+        elif exception.__class__.__name__ in self.known_errortypes:
+            return str(exception)
+        else:
+            logger.error('Unexpected exception: %r' % exception)
+            return _('An unexpected error has occurred.')
+
+    def get_success_message(self, value):
+        return _('The task has been completed.')