Add rendered preview in admin to fix #325

post_office/admin.py

@@ -1,30 +1,38 @@
 import re
 
 from django import forms
-from django.db import models
-from django.contrib import admin
 from django.conf import settings
-from django.conf.urls import re_path
+from django.contrib import admin
 from django.core.exceptions import ValidationError
 from django.core.mail.message import SafeMIMEText
+from django.db import models
 from django.forms import BaseInlineFormSet
 from django.forms.widgets import TextInput
-from django.http.response import HttpResponse, HttpResponseNotFound
-from django.template import Context, Template
+from django.http.response import HttpResponse
+from django.http.response import HttpResponseNotFound
+from django.template import Context
+from django.template import Template
+from django.urls import re_path
 from django.urls import reverse
 from django.utils.html import format_html
 from django.utils.text import Truncator
 from django.utils.translation import gettext_lazy as _
 
+from . import settings as post_office_settings
 from .fields import CommaSeparatedEmailField
-from .models import Attachment, Log, Email, EmailTemplate, STATUS
+from .models import Attachment
+from .models import Email
+from .models import EmailTemplate
+from .models import Log
+from .models import STATUS
 from .sanitizer import clean_html
 
 
 def get_message_preview(instance):
     return ('{0}...'.format(instance.message[:25]) if len(instance.message) > 25
             else instance.message)
 
+
 get_message_preview.short_description = 'Message'
 
 
@@ -42,7 +50,8 @@ def get_queryset(self, request):
             a.id
             for a in queryset
             if isinstance(a.attachment.headers, dict)
-            and a.attachment.headers.get("Content-Disposition", "").startswith("inline")
+               and a.attachment.headers.get("Content-Disposition",
+                                            "").startswith("inline")
         ]
         return queryset.exclude(id__in=inlined_attachments)
 
@@ -78,13 +87,16 @@ def requeue(modeladmin, request, queryset):
     """An admin action to requeue emails."""
     queryset.update(status=STATUS.queued)
 
+
 requeue.short_description = 'Requeue selected emails'
 
 
 class EmailAdmin(admin.ModelAdmin):
-    list_display = ['truncated_message_id', 'to_display', 'shortened_subject', 'status', 'last_updated', 'scheduled_time', 'use_template']
+    list_display = ['truncated_message_id', 'to_display', 'shortened_subject',
+                    'status', 'last_updated', 'scheduled_time', 'use_template']
     search_fields = ['to', 'subject']
-    readonly_fields = ['message_id', 'render_subject', 'render_plaintext_body',  'render_html_body']
+    readonly_fields = ['message_id', 'render_subject', 'render_plaintext_body',
+                       'render_html_body']
     date_hierarchy = 'last_updated'
     inlines = [AttachmentInline, LogInline]
     list_filter = ['status', 'template__language', 'template__name']
@@ -95,7 +107,8 @@ class EmailAdmin(admin.ModelAdmin):
 
     def get_urls(self):
         urls = [
-            re_path(r'^(?P<pk>\d+)/image/(?P<content_id>[0-9a-f]{32})$', self.fetch_email_image, name='post_office_email_image'),
+            re_path(r'^(?P<pk>\d+)/image/(?P<content_id>[0-9a-f]{32})$',
+                    self.fetch_email_image, name='post_office_email_image'),
         ]
         urls.extend(super().get_urls())
         return urls
@@ -120,7 +133,8 @@ def has_add_permission(self, request):
 
     def shortened_subject(self, instance):
         if instance.template:
-            template_cache_key = '_subject_template_' + str(instance.template_id)
+            template_cache_key = '_subject_template_' + str(
+                instance.template_id)
             template = getattr(self, template_cache_key, None)
             if template is None:
                 # cache compiled template to speed up rendering of list view
@@ -141,7 +155,8 @@ def use_template(self, instance):
     use_template.boolean = True
 
     def get_fieldsets(self, request, obj=None):
-        fields = ['from_email', 'to', 'cc', 'bcc', 'priority', ('status', 'scheduled_time')]
+        fields = ['from_email', 'to', 'cc', 'bcc', 'priority',
+                  ('status', 'scheduled_time')]
         if obj.message_id:
             fields.insert(0, 'message_id')
         fieldsets = [(None, {'fields': fields})]
@@ -157,16 +172,19 @@ def get_fieldsets(self, request, obj=None):
 
         if has_html_content:
             fieldsets.append(
-                (_("HTML Email"), {'fields': ['render_subject', 'render_html_body']})
+                (_("HTML Email"),
+                 {'fields': ['render_subject', 'render_html_body']})
             )
             if has_plaintext_content:
                 fieldsets.append(
-                    (_("Text Email"), {'classes': ['collapse'], 'fields': ['render_plaintext_body']})
+                    (_("Text Email"), {'classes': ['collapse'],
+                                       'fields': ['render_plaintext_body']})
                 )
         elif has_plaintext_content:
             fieldsets.append(
-                (_("Text Email"), {'fields': ['render_subject', 'render_plaintext_body']})
-             )
+                (_("Text Email"),
+                 {'fields': ['render_subject', 'render_plaintext_body']})
+            )
 
         return fieldsets
 
@@ -178,17 +196,20 @@ def render_subject(self, instance):
 
     def render_plaintext_body(self, instance):
         for message in instance.email_message().message().walk():
-            if isinstance(message, SafeMIMEText) and message.get_content_type() == 'text/plain':
+            if isinstance(message,
+                          SafeMIMEText) and message.get_content_type() == 'text/plain':
                 return format_html('<pre>{}</pre>', message.get_payload())
 
     render_plaintext_body.short_description = _("Mail Body")
 
     def render_html_body(self, instance):
         pattern = re.compile('cid:([0-9a-f]{32})')
-        url = reverse('admin:post_office_email_image', kwargs={'pk': instance.id, 'content_id': 32 * '0'})
+        url = reverse('admin:post_office_email_image',
+                      kwargs={'pk': instance.id, 'content_id': 32 * '0'})
         url = url.replace(32 * '0', r'\1')
         for message in instance.email_message().message().walk():
-            if isinstance(message, SafeMIMEText) and message.get_content_type() == 'text/html':
+            if isinstance(message,
+                          SafeMIMEText) and message.get_content_type() == 'text/html':
                 payload = message.get_payload(decode=True).decode('utf-8')
                 return clean_html(pattern.sub(url, payload))
 
@@ -197,8 +218,10 @@ def render_html_body(self, instance):
     def fetch_email_image(self, request, pk, content_id):
         instance = self.get_object(request, pk)
         for message in instance.email_message().message().walk():
-            if message.get_content_maintype() == 'image' and message.get('Content-Id')[1:33] == content_id:
-                return HttpResponse(message.get_payload(decode=True), content_type=message.get_content_type())
+            if message.get_content_maintype() == 'image' and message.get(
+                    'Content-Id')[1:33] == content_id:
+                return HttpResponse(message.get_payload(decode=True),
+                                    content_type=message.get_content_type())
         return HttpResponseNotFound()
 
 
@@ -239,7 +262,8 @@ class EmailTemplateAdminForm(forms.ModelForm):
 
     class Meta:
         model = EmailTemplate
-        fields = ['name', 'description', 'subject', 'content', 'html_content', 'language',
+        fields = ['name', 'description', 'subject', 'content', 'html_content',
+                  'language',
                   'default_template']
 
     def __init__(self, *args, **kwargs):
@@ -249,48 +273,127 @@ def __init__(self, *args, **kwargs):
             self.fields['language'].disabled = True
 
 
+def _create_iframe(src, height):
+    return format_html('''
+        <iframe
+            style="width: 80%; height: {height}px;"
+            src="{src}">'
+            sandbox
+        </iframe>
+        ''', height=height, src=src)
+
+
 class EmailTemplateInline(admin.StackedInline):
     form = EmailTemplateAdminForm
     formset = EmailTemplateAdminFormSet
     model = EmailTemplate
     extra = 0
-    fields = ('language', 'subject', 'content', 'html_content',)
+    fields = ('language', 'subject', 'content', 'html_content',
+              'rendered_content', 'rendered_html_content',)
+    readonly_fields = 'rendered_content', 'rendered_html_content'
     formfield_overrides = {
         models.CharField: {'widget': SubjectField}
     }
 
+    def rendered_content(self, instance):
+        if instance.content:
+            src = '?preview=text&language={}'.format(instance.language)
+            height = instance.content.count('\n') * 25
+            return _create_iframe(src, height)
+        else:
+            return ''
+
+    def rendered_html_content(self, instance):
+        if instance.html_content:
+            src = '?preview=text&language={}'.format(instance.language)
+            return _create_iframe(src, 800)
+        else:
+            return ''
+
     def get_max_num(self, request, obj=None, **kwargs):
         return len(settings.LANGUAGES)
 
 
 class EmailTemplateAdmin(admin.ModelAdmin):
     form = EmailTemplateAdminForm
-    list_display = ('name', 'description_shortened', 'subject', 'languages_compact', 'created')
+    list_display = (
+        'name', 'description_shortened', 'subject', 'languages_compact',
+        'created')
     search_fields = ('name', 'description', 'subject')
+    readonly_fields = 'rendered_content', 'rendered_html_content'
     fieldsets = [
         (None, {
             'fields': ('name', 'description'),
         }),
         (_("Default Content"), {
             'fields': ('subject', 'content', 'html_content'),
         }),
+        (_("Preview"), {
+            'fields': ('example_context', 'rendered_content',
+                       'rendered_html_content'),
+        }),
     ]
     inlines = (EmailTemplateInline,) if settings.USE_I18N else ()
     formfield_overrides = {
         models.CharField: {'widget': SubjectField}
     }
+    change_form_template = 'admin/post_office/EmailTemplate/change_form.html'
+
+    def change_view(self, request, object_id, form_url='', extra_context=None):
+        if request.GET.get('preview'):
+            instance = self.model.objects.get(id=object_id)
+            engine = post_office_settings.get_template_engine()
+
+            if request.GET.get('language'):
+                template_instance = instance.translated_templates.filter(
+                    language=request.GET.get('language'),
+                ).first()
+            else:
+                template_instance = instance
+
+            if request.GET.get('preview') == 'html':
+                template = engine.from_string(
+                    template_instance.html_content
+                        .replace('inline_image', 'static')
+                        .replace(' post_office ', ' static '))
+            else:
+                template = engine.from_string(
+                    '<pre>%s</pre>' % template_instance.content)
+
+            return HttpResponse(clean_html(template.render(
+                instance.example_context)))
+
+        return super(EmailTemplateAdmin, self).change_view(
+            request, object_id, form_url=form_url, extra_context=extra_context)
+
+    def rendered_content(self, instance):
+        if instance.content:
+            src = '?preview=text'
+            height = instance.content.count('\n') * 25
+            return _create_iframe(src, height)
+        else:
+            return ''
+
+    def rendered_html_content(self, instance):
+        if instance.html_content:
+            return _create_iframe('?preview=html', 800)
+        else:
+            return ''
 
     def get_queryset(self, request):
         return self.model.objects.filter(default_template__isnull=True)
 
     def description_shortened(self, instance):
         return Truncator(instance.description.split('\n')[0]).chars(200)
+
     description_shortened.short_description = _("Description")
     description_shortened.admin_order_field = 'description'
 
     def languages_compact(self, instance):
-        languages = [tt.language for tt in instance.translated_templates.order_by('language')]
+        languages = [tt.language for tt in
+                     instance.translated_templates.order_by('language')]
         return ', '.join(languages)
+
     languages_compact.short_description = _("Languages")
 
     def save_model(self, request, obj, form, change):
@@ -305,6 +408,7 @@ class AttachmentAdmin(admin.ModelAdmin):
     list_display = ['name', 'file']
     filter_horizontal = ['emails']
 
+
 admin.site.register(Email, EmailAdmin)
 admin.site.register(Log, LogAdmin)
 admin.site.register(EmailTemplate, EmailTemplateAdmin)

post_office/migrations/0012_add_example_context.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.2.10 on 2021-12-12 02:17
+
+from django.db import migrations, models
+import jsonfield.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('post_office', '0011_models_help_text'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='emailtemplate',
+            name='example_context',
+            field=jsonfield.fields.JSONField(blank=True, null=True, verbose_name='Context'),
+        ),
+    ]

post_office/models.py

@@ -269,6 +269,7 @@ class EmailTemplate(models.Model):
         default='', blank=True)
     default_template = models.ForeignKey('self', related_name='translated_templates',
         null=True, default=None, verbose_name=_('Default template'), on_delete=models.CASCADE)
+    example_context = context_field_class(_('Context'), blank=True, null=True)
 
     objects = EmailTemplateManager()