Prevent multiple TaskState approvals/rejections. Allow TaskState to be passed through to workflow_action to prevent race conditions: ie reviewer approving while in the meantime edits have been made. Add a new task preview view to allow preview of the revision in moderation in a specific task.

wagtail/admin/templates/wagtailadmin/notifications/task_state_approved.html

@@ -3,6 +3,5 @@
 
 {% block content %}
     <p>{% blocktrans with title=page.get_admin_display_title task=task.name %}The page "{{ title }}" has been approved in moderation stage "{{ task }}".{% endblocktrans %}</p>
-    <p>{% trans "You can preview the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}</a><br/></p>
     <p>{% trans "You can edit the page here:"%} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}</a></p>
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/task_state_approved.txt

@@ -3,6 +3,5 @@
 
 {% block content %}
 {% blocktrans with title=page.get_admin_display_title|safe task=task.name %}The page "{{ title }}" has been approved in moderation stage "{{ task }}".{% endblocktrans %}
-{% trans "You can preview the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}
 {% trans "You can edit the page here:"%} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/task_state_rejected.txt

@@ -3,6 +3,5 @@
 
 {% block content %}
 {% blocktrans with title=page.get_admin_display_title|safe task=task.name %}The page "{{ title }}" has been rejected in moderation stage "{{ task }}".{% endblocktrans %}
-
 {% trans "You can edit the page here:"%} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/task_state_submitted.html

@@ -6,7 +6,7 @@
     <p>{% blocktrans with task=task.name title=page.get_admin_display_title %}The page "{{ title }}" has been submitted for approval in moderation stage "{{ task }}".{% endblocktrans %}</p>
 
     <p>
-        {% trans "You can preview the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}</a><br/>
+        {% trans "You can preview the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:workflow_preview' page.id task.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:workflow_preview' page.id task.id %}</a><br/>
         {% trans "You can edit the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}</a>
     </p>
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/task_state_submitted.txt

@@ -6,7 +6,7 @@
 {% blocktrans with task=task.name title=page.get_admin_display_title %}The page "{{ title }}" has been submitted for approval to moderation stage "{{ task }}".{% endblocktrans %}
 
 
-{% trans "You can preview the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}
+{% trans "You can preview the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:workflow_preview' page.id task.id %}
 {% trans "You can edit the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}
 
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/workflow_state_submitted.html

@@ -6,7 +6,6 @@
     <p>{% blocktrans with workflow=workflow.name title=page.get_admin_display_title %}The page "{{ title }}" has been submitted for moderation to workflow "{{ workflow }}".{% endblocktrans %}</p>
 
     <p>
-        {% trans "You can preview the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}</a><br/>
         {% trans "You can edit the page here:" %} <a href="{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}">{{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}</a>
     </p>
 {% endblock %}

wagtail/admin/templates/wagtailadmin/notifications/workflow_state_submitted.txt

@@ -6,7 +6,6 @@
 {% blocktrans with workflow=workflow.name title=page.get_admin_display_title %}The page "{{ title }}" has been submitted for moderation to workflow "{{ workflow }}".{% endblocktrans %}
 
 
-{% trans "You can preview the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_on_edit' page.id %}
 {% trans "You can edit the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' page.id %}
 
 {% endblock %}

wagtail/admin/templates/wagtailadmin/pages/edit.html

@@ -174,12 +174,11 @@
                     actionFieldElement.value = buttonElement.dataset.workflowAction;
                     formElement.appendChild(actionFieldElement);
 
-                    var nextFieldElement = document.createElement('input');
+                    var taskFieldElement = document.createElement('input');
-                    nextFieldElement.type = 'hidden';
+                    taskFieldElement.type = 'hidden';
-                    nextFieldElement.name = 'next';
+                    taskFieldElement.name = 'task_id';
-                    {% url 'wagtailadmin_home' as dashboard_url %}
+                    taskFieldElement.value = {{ current_task_state.id }};
-                    nextFieldElement.value = '{{ dashboard_url|escapejs }}';
+                    formElement.appendChild(taskFieldElement);
-                    formElement.appendChild(nextFieldElement);
 
                     document.body.appendChild(formElement);
                     formElement.submit();

wagtail/admin/urls/pages.py

@@ -26,6 +26,7 @@ urlpatterns = [
     path('<int:page_id>/copy/', pages.copy, name='copy'),
 
     path('workflow/action/<int:page_id>/', pages.workflow_action, name='workflow_action'),
+    path('workflow/preview/<int:page_id>/<int:task_id>/', pages.preview_revision_for_task, name='workflow_preview'),
 
     path('moderation/<int:revision_id>/approve/', pages.approve_moderation, name='approve_moderation'),
     path('moderation/<int:revision_id>/reject/', pages.reject_moderation, name='reject_moderation'),

wagtail/admin/views/pages.py

@@ -651,11 +651,7 @@ def edit(request, page_id):
         'has_unsaved_changes': has_unsaved_changes,
         'page_locked': page_perms.page_locked(),
         'workflow_actions': page.current_workflow_task.get_actions(page, request.user) if page.current_workflow_task else [],
-        'task_statuses': task_statuses,
+        'current_task_state': page.current_workflow_task_state
-        'current_task_number': current_task_number,
-        'task_name': task_name,
-        'workflow_name': workflow_name,
-        'total_tasks': total_tasks
     })
 
 
@@ -1196,20 +1192,27 @@ def workflow_action(request, page_id):
 
     redirect_to = request.POST.get('next', None)
     if not redirect_to or not is_safe_url(url=redirect_to, allowed_hosts={request.get_host()}):
-        redirect_to = reverse('wagtailadmin_explore', args=[page.get_parent().id])
+        redirect_to = reverse('wagtailadmin_pages:edit', args=[page_id])
 
     if not page.workflow_in_progress():
         messages.error(request, _("The page '{0}' is not currently awaiting moderation.").format(page.get_admin_display_title()))
         return redirect(redirect_to)
 
-    actions = page.current_workflow_task.get_actions(page, request.user)
+    task_state_id = request.POST.get('task_state_id', None)
+
+    task_state = TaskState.objects.get(id=task_state_id) if task_state_id else page.current_workflow_task_state
+    task_state = task_state.specific
+
+    task = task_state.task.specific
+
+    actions = task.get_actions(page, request.user)
 
     action_name = request.POST.get('action')
 
     if action_name not in set(action[0] for action in actions):
         raise PermissionDenied
 
-    page.current_workflow_task.on_action(page.current_workflow_task_state, request.user, action_name)
+    task.on_action(task_state, request.user, action_name)
 
     return redirect(redirect_to)
 
@@ -1236,6 +1239,33 @@ def preview_for_moderation(request, revision_id):
     })
 
 
+@require_GET
+def preview_revision_for_task(request, page_id, task_id):
+    """Preview the revision linked to the in-progress TaskState of a specified Task. This enables pages in moderation
+    to be edited and new TaskStates linked to the new revisions created, with preview links remaining valid"""
+
+    page = Page.objects.get(id=page_id)
+    task = Task.objects.get(id=task_id).specific
+    try:
+        task_state = TaskState.objects.get(page_revision__page=page, task=task, status=TaskState.STATUS_IN_PROGRESS)
+    except TaskState.DoesNotExist:
+        messages.error(request, _("The page '{0}' is not currently awaiting moderation in task '{1}'.").format(page.get_admin_display_title(), task.name))
+        return redirect('wagtailadmin_home')
+
+    revision = task_state.page_revision
+
+    if not task.get_actions(page, request.user):
+        raise PermissionDenied
+
+    page_to_view = revision.as_page_object()
+
+    # TODO: provide workflow actions within this view
+
+    return page_to_view.make_preview_request(request, page.default_preview_mode, extra_request_attrs={
+        'revision_id': revision.id
+    })
+
+
 @require_POST
 def lock(request, page_id):
     # Get the page

wagtail/core/models.py

@@ -9,7 +9,7 @@ from django.contrib.auth.models import Group, Permission
 from django.contrib.contenttypes.models import ContentType
 from django.core import checks
 from django.core.cache import cache
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ValidationError, PermissionDenied
 from django.core.handlers.base import BaseHandler
 from django.core.handlers.wsgi import WSGIRequest
 from django.db import models, transaction
@@ -2742,12 +2742,16 @@ class WorkflowState(models.Model):
         return Task.objects.filter(workflow_tasks__workflow=self.workflow, active=True).exclude(Q(task_states__page_revision=self.page.get_latest_revision()), Q(task_states__status=TaskState.STATUS_APPROVED) | Q(task_states__status=TaskState.STATUS_SKIPPED)).order_by('workflow_tasks__sort_order').first()
 
     def cancel(self, user=None):
+        if self.status != self.STATUS_IN_PROGRESS:
+            raise PermissionDenied
         self.status = 'cancelled'
         self.save()
         workflow_cancelled.send(sender=self.__class__, instance=self, user=user)
 
     @transaction.atomic
     def finish(self, user=None):
+        if self.status != self.STATUS_IN_PROGRESS:
+            raise PermissionDenied
         self.status = 'approved'
         self.save()
         self.on_finish()
@@ -2827,6 +2831,8 @@ class TaskState(models.Model):
 
     @transaction.atomic
     def approve(self, user=None):
+        if self.status != self.STATUS_IN_PROGRESS:
+            raise PermissionDenied
         self.status = 'approved'
         self.finished_at = timezone.now()
         self.save()
@@ -2836,6 +2842,8 @@ class TaskState(models.Model):
 
     @transaction.atomic
     def reject(self, user=None):
+        if self.status != self.STATUS_IN_PROGRESS:
+            raise PermissionDenied
         self.status = 'rejected'
         self.finished_at = timezone.now()
         self.save()