Backport workflow preview refactor

GitLab issue #532.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -5,6 +5,7 @@
   links.
 - Use Select2 widget for the document type selection form.
 - Backport the vertical main menu update.
+- Backport workflow preview refactor. GitLab issue #532.
 
 3.2.5 (2019-07-05)
 ==================

docs/releases/3.3.rst

@@ -17,6 +17,7 @@ Changes
   The vertical menu remain open even when clicking on items and upon
   a browser refresh will also restore its state to match the selected
   view.
+- Backport workflow preview refactor. GitLab issue #532.
 
 Removals
 --------
@@ -105,6 +106,6 @@ Backward incompatible changes
 Bugs fixed or issues closed
 ---------------------------
 
-- :gitlab-issue:`XX` 
+- :gitlab-issue:`532` Workflow preview isn't updated right after transitions are modified
 
 .. _PyPI: https://pypi.python.org/pypi/mayan-edms/

mayan/apps/document_states/api_views.py

@@ -1,6 +1,8 @@
 from __future__ import absolute_import, unicode_literals
 
+from django.http import HttpResponse
 from django.shortcuts import get_object_or_404
+from django.views.decorators.cache import cache_control, patch_cache_control
 
 from rest_framework import generics
 
@@ -10,6 +12,7 @@ from mayan.apps.documents.permissions import permission_document_type_view
 from mayan.apps.rest_api.filters import MayanObjectPermissionsFilter
 from mayan.apps.rest_api.permissions import MayanPermission
 
+from .literals import WORKFLOW_IMAGE_TASK_TIMEOUT
 from .models import Workflow
 from .permissions import (
     permission_workflow_create, permission_workflow_delete,
@@ -23,6 +26,10 @@ from .serializers import (
     WritableWorkflowTransitionSerializer
 )
 
+from .settings import settings_workflow_image_cache_time
+from .storages import storage_workflowimagecache
+from .tasks import task_generate_workflow_image
+
 
 class APIDocumentTypeWorkflowListView(generics.ListAPIView):
     """
@@ -172,6 +179,41 @@ class APIWorkflowDocumentTypeView(generics.RetrieveDestroyAPIView):
         self.get_workflow().document_types.remove(instance)
 
 
+class APIWorkflowImageView(generics.RetrieveAPIView):
+    """
+    get: Returns an image representation of the selected workflow.
+    """
+    filter_backends = (MayanObjectPermissionsFilter,)
+    mayan_object_permissions = {
+        'GET': (permission_workflow_view,),
+    }
+    queryset = Workflow.objects.all()
+
+    def get_serializer(self, *args, **kwargs):
+        return None
+
+    def get_serializer_class(self):
+        return None
+
+    @cache_control(private=True)
+    def retrieve(self, request, *args, **kwargs):
+        task = task_generate_workflow_image.apply_async(
+            kwargs=dict(
+                document_state_id=self.get_object().pk,
+            )
+        )
+
+        cache_filename = task.get(timeout=WORKFLOW_IMAGE_TASK_TIMEOUT)
+        with storage_workflowimagecache.open(cache_filename) as file_object:
+            response = HttpResponse(file_object.read(), content_type='image')
+            if '_hash' in request.GET:
+                patch_cache_control(
+                    response,
+                    max_age=settings_workflow_image_cache_time.value
+                )
+            return response
+
+
 class APIWorkflowListView(generics.ListCreateAPIView):
     """
     get: Returns a list of all the workflows.

mayan/apps/document_states/fields.py

@@ -0,0 +1,9 @@
+from __future__ import absolute_import, unicode_literals
+
+from django import forms
+
+from .widgets import WorkflowImageWidget
+
+
+class WorfklowImageField(forms.fields.Field):
+    widget = WorkflowImageWidget

mayan/apps/document_states/forms.py

@@ -12,10 +12,10 @@ from django.utils.translation import ugettext_lazy as _
 from mayan.apps.common.forms import DynamicModelForm
 
 from .classes import WorkflowAction
+from .fields import WorfklowImageField
 from .models import (
     Workflow, WorkflowState, WorkflowStateAction, WorkflowTransition
 )
-from .widgets import WorkflowImageWidget
 
 
 class WorkflowActionSelectionForm(forms.Form):
@@ -188,9 +188,9 @@ class WorkflowInstanceTransitionForm(forms.Form):
 
 
 class WorkflowPreviewForm(forms.Form):
-    preview = forms.CharField(widget=WorkflowImageWidget())
+    workflow = WorfklowImageField()
 
     def __init__(self, *args, **kwargs):
         instance = kwargs.pop('instance', None)
         super(WorkflowPreviewForm, self).__init__(*args, **kwargs)
-        self.fields['preview'].initial = instance
+        self.fields['workflow'].initial = instance

mayan/apps/document_states/literals.py

@@ -9,3 +9,4 @@ WORKFLOW_ACTION_WHEN_CHOICES = (
     (WORKFLOW_ACTION_ON_ENTRY, _('On entry')),
     (WORKFLOW_ACTION_ON_EXIT, _('On exit')),
 )
+WORKFLOW_IMAGE_TASK_TIMEOUT = 60

mayan/apps/document_states/models.py

@@ -1,12 +1,16 @@
 from __future__ import absolute_import, unicode_literals
 
+import hashlib
 import json
 import logging
 
+from furl import furl
 from graphviz import Digraph
 
 from django.conf import settings
+from django.core import serializers
 from django.core.exceptions import PermissionDenied, ValidationError
+from django.core.files.base import ContentFile
 from django.db import IntegrityError, models, transaction
 from django.db.models import F, Max, Q
 from django.urls import reverse
@@ -27,6 +31,7 @@ from .literals import (
 )
 from .managers import WorkflowManager
 from .permissions import permission_workflow_transition
+from .storages import storage_workflowimagecache
 
 logger = logging.getLogger(__name__)
 
@@ -63,9 +68,49 @@ class Workflow(models.Model):
     def __str__(self):
         return self.label
 
+    def generate_image(self):
+        cache_filename = '{}-{}'.format(self.id, self.get_hash())
+        image = self.render()
+
+        # Since open "wb+" doesn't create files, check if the file
+        # exists, if not then create it
+        if not storage_workflowimagecache.exists(cache_filename):
+            storage_workflowimagecache.save(
+                name=cache_filename, content=ContentFile(content='')
+            )
+
+        with storage_workflowimagecache.open(cache_filename, mode='wb+') as file_object:
+            file_object.write(image)
+
+        return cache_filename
+
+    def get_api_image_url(self, *args, **kwargs):
+        final_url = furl()
+        final_url.args = kwargs
+        final_url.path = reverse(
+            viewname='rest_api:workflow-image',
+            kwargs={'pk': self.pk}
+        )
+        final_url.args['_hash'] = self.get_hash()
+
+        return final_url.tostr()
+
     def get_document_types_not_in_workflow(self):
         return DocumentType.objects.exclude(pk__in=self.document_types.all())
 
+    def get_hash(self):
+        objects_lists = list(
+            Workflow.objects.filter(pk=self.pk)
+        ) + list(
+            WorkflowState.objects.filter(workflow__pk=self.pk)
+        ) + list(
+            WorkflowTransition.objects.filter(workflow__pk=self.pk)
+        )
+
+        return hashlib.sha256(
+            serializers.serialize('json', objects_lists)
+        ).hexdigest()
+
     def get_initial_state(self):
         try:
             return self.states.get(initial=True)

mayan/apps/document_states/queues.py

@@ -3,12 +3,21 @@ from __future__ import absolute_import, unicode_literals
 from django.utils.translation import ugettext_lazy as _
 
 from mayan.apps.task_manager.classes import CeleryQueue
-from mayan.apps.task_manager.workers import worker_slow
+from mayan.apps.task_manager.workers import worker_fast, worker_slow
 
 queue_document_states = CeleryQueue(
-    name='document_states', label=_('Document states'), worker=worker_slow
+    label=_('Document states'), name='document_states', worker=worker_slow
 )
+queue_document_states_fast = CeleryQueue(
+    label=_('Document states fast'), name='document_states_fast',
+    worker=worker_fast
+)
+
 queue_document_states.add_task_type(
-    dotted_path='mayan.apps.document_states.tasks.task_launch_all_workflows',
-    label=_('Launch all workflows')
+    label=_('Launch all workflows'),
+    dotted_path='mayan.apps.document_states.tasks.task_launch_all_workflows'
+)
+queue_document_states_fast.add_task_type(
+    label=_('Generate workflow previews'),
+    dotted_path='mayan.apps.document_states.tasks.task_generate_workflow_image'
 )

mayan/apps/document_states/settings.py

@@ -0,0 +1,32 @@
+from __future__ import unicode_literals
+
+import os
+
+from django.conf import settings
+from django.utils.translation import ugettext_lazy as _
+
+from mayan.apps.smart_settings import Namespace
+
+namespace = Namespace(label=_('Workflows'), name='document_states')
+
+settings_workflow_image_cache_time = namespace.add_setting(
+    global_name='WORKFLOWS_IMAGE_CACHE_TIME', default='31556926',
+    help_text=_(
+        'Time in seconds that the browser should cache the supplied workflow '
+        'images. The default of 31559626 seconds corresponde to 1 year.'
+    )
+)
+setting_workflowimagecache_storage = namespace.add_setting(
+    global_name='WORKFLOWS_IMAGE_CACHE_STORAGE_BACKEND',
+    default='django.core.files.storage.FileSystemStorage', help_text=_(
+        'Path to the Storage subclass to use when storing the cached '
+        'workflow image files.'
+    )
+)
+setting_workflowimagecache_storage_arguments = namespace.add_setting(
+    global_name='WORKFLOWS_IMAGE_CACHE_STORAGE_BACKEND_ARGUMENTS',
+    default={'location': os.path.join(settings.MEDIA_ROOT, 'workflows')},
+    help_text=_(
+        'Arguments to pass to the WORKFLOWS_IMAGE_CACHE_STORAGE_BACKEND.'
+    )
+)

mayan/apps/document_states/storages.py

@@ -0,0 +1,12 @@
+from __future__ import unicode_literals
+
+from django.utils.module_loading import import_string
+
+from .settings import (
+    setting_workflowimagecache_storage,
+    setting_workflowimagecache_storage_arguments
+)
+
+storage_workflowimagecache = import_string(
+    dotted_path=setting_workflowimagecache_storage.value
+)(**setting_workflowimagecache_storage_arguments.value)

mayan/apps/document_states/tasks.py

@@ -9,6 +9,17 @@ from mayan.celery import app
 logger = logging.getLogger(__name__)
 
 
+@app.task()
+def task_generate_workflow_image(document_state_id):
+    Workflow = apps.get_model(
+        app_label='document_states', model_name='Workflow'
+    )
+
+    workflow = Workflow.objects.get(pk=document_state_id)
+
+    return workflow.generate_image()
+
+
 @app.task(ignore_result=True)
 def task_launch_all_workflows():
     Document = apps.get_model(app_label='documents', model_name='Document')

mayan/apps/document_states/templates/document_states/forms/widgets/workflow_image.html

@@ -0,0 +1,2 @@
+<img class="img-responsive" name="{{ widget.name }}" {% include "django/forms/widgets/attrs.html" %} src="{{ widget.value.get_api_image_url }}" style="margin:auto;" />
+

mayan/apps/document_states/urls.py

@@ -4,9 +4,10 @@ from django.conf.urls import url
 
 from .api_views import (
     APIDocumentTypeWorkflowListView, APIWorkflowDocumentTypeList,
-    APIWorkflowDocumentTypeView, APIWorkflowInstanceListView,
-    APIWorkflowInstanceView, APIWorkflowInstanceLogEntryListView,
-    APIWorkflowListView, APIWorkflowStateListView, APIWorkflowStateView,
+    APIWorkflowDocumentTypeView, APIWorkflowImageView,
+    APIWorkflowInstanceListView, APIWorkflowInstanceView,
+    APIWorkflowInstanceLogEntryListView, APIWorkflowListView,
+    APIWorkflowStateListView, APIWorkflowStateView,
     APIWorkflowTransitionListView, APIWorkflowTransitionView, APIWorkflowView
 )
 from .views import (
@@ -22,7 +23,7 @@ from .views import (
     SetupWorkflowTransitionEditView,
     SetupWorkflowTransitionTriggerEventListView, ToolLaunchAllWorkflows,
     WorkflowDocumentListView, WorkflowInstanceDetailView,
-    WorkflowImageView, WorkflowInstanceTransitionView, WorkflowListView,
+    WorkflowInstanceTransitionView, WorkflowListView,
     WorkflowPreviewView, WorkflowStateDocumentListView, WorkflowStateListView,
 )
 from .views.workflow_views import SetupDocumentTypeWorkflowsView
@@ -167,11 +168,6 @@ urlpatterns = [
         view=WorkflowStateListView.as_view(),
         name='workflow_state_list'
     ),
-    url(
-        regex=r'^(?P<pk>\d+)/image/$',
-        view=WorkflowImageView.as_view(),
-        name='workflow_image'
-    ),
     url(
         regex=r'^(?P<pk>\d+)/preview/$',
         view=WorkflowPreviewView.as_view(),
@@ -204,6 +200,10 @@ api_urls = [
         view=APIWorkflowDocumentTypeView.as_view(),
         name='workflow-document-type-detail'
     ),
+    url(
+        regex=r'^workflows/(?P<pk>\d+)/image/$',
+        name='workflow-image', view=APIWorkflowImageView.as_view()
+    ),
     url(
         regex=r'^workflows/(?P<pk>[0-9]+)/states/$',
         view=APIWorkflowStateListView.as_view(), name='workflowstate-list'

mayan/apps/document_states/views/workflow_views.py

@@ -1,7 +1,6 @@
 from __future__ import absolute_import, unicode_literals
 
 from django.contrib import messages
-from django.core.files.base import ContentFile
 from django.db import transaction
 from django.http import Http404, HttpResponseRedirect
 from django.shortcuts import get_object_or_404
@@ -13,7 +12,7 @@ from mayan.apps.common.generics import (
     AddRemoveView, ConfirmView, FormView, SingleObjectCreateView,
     SingleObjectDeleteView, SingleObjectDetailView,
     SingleObjectDynamicFormCreateView, SingleObjectDynamicFormEditView,
-    SingleObjectDownloadView, SingleObjectEditView, SingleObjectListView
+    SingleObjectEditView, SingleObjectListView
 )
 from mayan.apps.common.mixins import ExternalObjectMixin
 from mayan.apps.documents.events import event_document_type_edited
@@ -49,7 +48,6 @@ from ..permissions import (
 from ..tasks import task_launch_all_workflows
 
 __all__ = (
-    'WorkflowImageView', 'WorkflowPreviewView',
     'SetupWorkflowListView', 'SetupWorkflowCreateView', 'SetupWorkflowEditView',
     'SetupWorkflowDeleteView', 'SetupWorkflowDocumentTypesView',
     'SetupWorkflowStateActionCreateView', 'SetupWorkflowStateActionDeleteView',
@@ -59,7 +57,8 @@ __all__ = (
     'SetupWorkflowStateListView', 'SetupWorkflowTransitionCreateView',
     'SetupWorkflowTransitionDeleteView', 'SetupWorkflowTransitionEditView',
     'SetupWorkflowTransitionListView',
-    'SetupWorkflowTransitionTriggerEventListView', 'ToolLaunchAllWorkflows'
+    'SetupWorkflowTransitionTriggerEventListView', 'ToolLaunchAllWorkflows',
+    'WorkflowPreviewView'
 )
 
 
@@ -750,26 +749,15 @@ class ToolLaunchAllWorkflows(ConfirmView):
         )
 
 
-class WorkflowImageView(SingleObjectDownloadView):
-    attachment = False
-    model = Workflow
-    object_permission = permission_workflow_view
-
-    def get_file(self):
-        workflow = self.get_object()
-        return ContentFile(workflow.render(), name=workflow.label)
-
-    def get_mimetype(self):
-        return 'image'
-
-
 class WorkflowPreviewView(SingleObjectDetailView):
     form_class = WorkflowPreviewForm
     model = Workflow
     object_permission = permission_workflow_view
+    pk_url_kwarg = 'pk'
 
     def get_extra_context(self):
         return {
             'hide_labels': True,
+            'object': self.get_object(),
             'title': _('Preview of: %s') % self.get_object()
         }

mayan/apps/document_states/widgets.py

@@ -1,8 +1,7 @@
 from __future__ import unicode_literals
 
 from django import forms
-from django.urls import reverse
-from django.utils.html import format_html_join, mark_safe
+from django.utils.html import format_html_join
 
 
 def widget_transition_events(transition):
@@ -15,23 +14,10 @@ def widget_transition_events(transition):
     )
 
 
-def widget_workflow_diagram(workflow):
-    return mark_safe(
-        '<img class="img-responsive" src="{}" style="margin:auto;">'.format(
-            reverse(
-                viewname='document_states:workflow_image', kwargs={
-                    'pk': workflow.pk
-                }
-            )
-        )
-    )
-
-
 class WorkflowImageWidget(forms.widgets.Widget):
-    def render(self, name, value, attrs=None):
-        if value:
-            output = []
-            output.append(widget_workflow_diagram(value))
-            return mark_safe(''.join(output))
-        else:
-            return ''
+    template_name = 'document_states/forms/widgets/workflow_image.html'
+
+    def format_value(self, value):
+        if value == '' or value is None:
+            return None
+        return value