Use TemplateField for Index expression field

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

HISTORY.rst

@@ -129,6 +129,8 @@
   now get the permission inheritance from their base models.
 - Update common.http.URL to allow passing a query dictionary.
 - Add the document template sandbox feature.
+- Use the generic TemplateField for the expression field
+  of index tree templates.
 
 3.2.10 (2019-XX-XX)
 ===================

mayan/apps/document_indexing/forms.py

@@ -1,52 +1,16 @@
 from __future__ import absolute_import, unicode_literals
 
 from django import forms
-from django.utils.encoding import force_text
 from django.utils.translation import ugettext_lazy as _
 
-from mayan.apps.common.classes import ModelProperty
 from mayan.apps.common.forms import FilteredSelectionForm
 from mayan.apps.documents.models import Document
+from mayan.apps.templating.fields import TemplateField
 
 from .models import Index, IndexTemplateNode
 from .permissions import permission_document_indexing_rebuild
 
 
-class DocumentTemplateSandboxForm(forms.Form):
-    template = forms.CharField(
-        help_text=_(
-            'The template string to be evaluated. The current document '
-            'is available as the {{ document }} variable.'
-        ), label=_('Template'), widget=forms.widgets.Textarea(
-            attrs={'rows': 5}
-        )
-    )
-    result = forms.CharField(
-        help_text=_('Resulting text from the evaluated template.'),
-        label=_('Result'), required=False, widget=forms.widgets.Textarea(
-            attrs={'rows': 5}
-        )
-    )
-
-    def __init__(self, *args, **kwargs):
-        super(DocumentTemplateSandboxForm, self).__init__(*args, **kwargs)
-        self.fields['template'].help_text = ' '.join(
-            [
-                force_text(self.fields['template'].help_text),
-                force_text(
-                    _(
-                        'Use Django\'s default templating language '
-                        '(https://docs.djangoproject.com/en/1.11/ref/templates/builtins/)'
-                    ),
-                ),
-                '<br>',
-                ModelProperty.get_help_text_for(
-                    model=Document, show_name=True
-                ).replace('\n', '<br>')
-            ]
-        )
-
-
 class IndexTemplateFilteredForm(FilteredSelectionForm):
     class Meta:
         allow_multiple = True
@@ -66,14 +30,9 @@ class IndexTemplateNodeForm(forms.ModelForm):
         super(IndexTemplateNodeForm, self).__init__(*args, **kwargs)
         self.fields['index'].widget = forms.widgets.HiddenInput()
         self.fields['parent'].widget = forms.widgets.HiddenInput()
-        self.fields['expression'].help_text = ' '.join(
-            [
-                force_text(self.fields['expression'].help_text),
-                '<br>',
-                ModelProperty.get_help_text_for(
-                    model=Document, show_name=True
-                ).replace('\n', '<br>')
-            ]
+        self.fields['expression'] = TemplateField(
+            label=_('Template'), model=Document,
+            model_variable='document', required=False
         )
 
     class Meta:

mayan/apps/document_indexing/views.py

@@ -1,11 +1,8 @@
 from __future__ import absolute_import, unicode_literals
 
 from django.contrib import messages
-from django.http import HttpResponseRedirect
 from django.shortcuts import get_object_or_404
-from django.template import (
-    Context, RequestContext, Template, TemplateSyntaxError
-)
+from django.template import RequestContext
 from django.urls import reverse, reverse_lazy
 from django.utils.html import mark_safe
 from django.utils.translation import ugettext_lazy as _, ungettext
@@ -15,8 +12,6 @@ from mayan.apps.common.generics import (
     AddRemoveView, ConfirmView, FormView, SingleObjectCreateView,
     SingleObjectDeleteView, SingleObjectEditView, SingleObjectListView
 )
-from mayan.apps.common.http import URL
-from mayan.apps.common.mixins import ExternalObjectMixin
 from mayan.apps.documents.events import event_document_type_edited
 from mayan.apps.documents.models import Document, DocumentType
 from mayan.apps.documents.permissions import (