Refactor and implement download code natively

- Use modified port of Django 2.2 FileResponse.
- Remove Django DownloadView library.

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

mayan/apps/common/compat.py

@@ -1,8 +1,14 @@
 from __future__ import unicode_literals
 
+import os
 import types
 
+from django.conf import settings
+from django.http.response import StreamingHttpResponse
 from django.utils import six
+from django.utils.six.moves.urllib.parse import quote
+
+from mayan.apps.mimetype.api import get_mimetype
 
 if six.PY3:
     dict_type = dict
@@ -22,3 +28,75 @@ except NameError:
     FileNotFoundErrorException = IOError
 else:
     FileNotFoundErrorException = FileNotFoundError  # NOQA
+
+
+class FileResponse(StreamingHttpResponse):
+    """
+    Port of Django's 2.2 FileResponse
+    Modified to allows downloading non file like content as attachment
+    A streaming HTTP response class optimized for files.
+    TODO: To be remove when the code moves to Django 2.2
+    """
+    block_size = 4096
+
+    def __init__(self, as_attachment=False, filename='', *args, **kwargs):
+        self.as_attachment = as_attachment
+        self.filename = filename
+        super(FileResponse, self).__init__(*args, **kwargs)
+
+    def _set_as_attachment(self, filename):
+        if self.as_attachment:
+            filename = self.filename or os.path.basename(filename)
+            if filename:
+                try:
+                    filename.encode('ascii')
+                    file_expr = 'filename="{}"'.format(filename)
+                except UnicodeEncodeError:
+                    file_expr = "filename*=utf-8''{}".format(quote(filename))
+                self['Content-Disposition'] = 'attachment; {}'.format(file_expr)
+
+    def _set_streaming_content(self, value):
+        if not hasattr(value, 'read'):
+            self.file_to_stream = None
+            result = super(FileResponse, self)._set_streaming_content(value)
+            self._set_as_attachment(filename=self.filename)
+
+            return result
+
+        self.file_to_stream = filelike = value
+        if hasattr(filelike, 'close'):
+            self._closable_objects.append(filelike)
+        value = iter(lambda: filelike.read(self.block_size), b'')
+        self.set_headers(filelike)
+        super(FileResponse, self)._set_streaming_content(value)
+
+    def set_headers(self, filelike):
+        """
+        Set some common response headers (Content-Length, Content-Type, and
+        Content-Disposition) based on the `filelike` response content.
+        """
+        encoding_map = {
+            'bzip2': 'application/x-bzip',
+            'gzip': 'application/gzip',
+            'xz': 'application/x-xz',
+        }
+        filename = getattr(filelike, 'name', None)
+        filename = filename if (isinstance(filename, str) and filename) else self.filename
+        if os.path.isabs(filename):
+            self['Content-Length'] = os.path.getsize(filelike.name)
+        elif hasattr(filelike, 'getbuffer'):
+            self['Content-Length'] = filelike.getbuffer().nbytes
+
+        if self.get('Content-Type', '').startswith(settings.DEFAULT_CONTENT_TYPE):
+            if self.file_to_stream:
+                content_type, encoding = get_mimetype(
+                    file_object=self.file_to_stream, mimetype_only=True
+                )
+                # Encoding isn't set to prevent browsers from automatically
+                # uncompressing files.
+                content_type = encoding_map.get(encoding, content_type)
+                self['Content-Type'] = content_type or 'application/octet-stream'
+            else:
+                self['Content-Type'] = 'application/octet-stream'
+
+        self._set_as_attachment(filename=filename)

mayan/apps/common/generics.py

@@ -11,15 +11,13 @@ from django.utils.translation import ugettext_lazy as _
 from django.views.generic import (
     FormView as DjangoFormView, DetailView, TemplateView
 )
+from django.views.generic.base import View
 from django.views.generic.detail import SingleObjectMixin
 from django.views.generic.edit import (
     CreateView, DeleteView, FormMixin, ModelFormMixin, UpdateView
 )
 from django.views.generic.list import ListView
 
-from django_downloadview import (
-    TextIteratorIO, VirtualDownloadView, VirtualFile
-)
 from pure_pagination.mixins import PaginationMixin
 
 from mayan.apps.acls.models import AccessControlList
@@ -36,11 +34,10 @@ from .literals import (
     TEXT_SORT_ORDER_VARIABLE_NAME
 )
 from .mixins import (
-    DeleteExtraDataMixin, DynamicFormViewMixin, ExternalObjectMixin,
-    ExtraContextMixin, FormExtraKwargsMixin, MultipleObjectMixin,
-    ObjectActionMixin, ObjectNameMixin,
-    ObjectPermissionCheckMixin, RedirectionMixin, RestrictedQuerysetMixin,
-    ViewPermissionCheckMixin
+    DeleteExtraDataMixin, DownloadMixin, DynamicFormViewMixin,
+    ExternalObjectMixin, ExtraContextMixin, FormExtraKwargsMixin,
+    MultipleObjectMixin, ObjectActionMixin, ObjectNameMixin,
+    RedirectionMixin, RestrictedQuerysetMixin, ViewPermissionCheckMixin
 )
 
 from .settings import setting_paginate_by
@@ -491,7 +488,9 @@ class MultipleObjectConfirmActionView(
 
 
 class SimpleView(ViewPermissionCheckMixin, ExtraContextMixin, TemplateView):
-    pass
+    """
+    Basic template view class with permission check and extra context
+    """
 
 
 class SingleObjectCreateView(
@@ -657,9 +656,52 @@ class SingleObjectDetailView(
             return super(SingleObjectDetailView, self).get_queryset()
 
 
-class SingleObjectDownloadView(ViewPermissionCheckMixin, ObjectPermissionCheckMixin, VirtualDownloadView, SingleObjectMixin):
-    TextIteratorIO = TextIteratorIO
-    VirtualFile = VirtualFile
+class BaseDownloadView(DownloadMixin, ViewPermissionCheckMixin, View):
+    def get(self, request, *args, **kwargs):
+        return self.render_to_response()
+
+
+class SingleObjectDownloadView(
+    RestrictedQuerysetMixin, SingleObjectMixin, BaseDownloadView
+):
+    def get(self, request, *args, **kwargs):
+        self.object = self.get_object()
+        return super(SingleObjectDownloadView, self).get(
+            request, *args, **kwargs
+        )
+
+    def get_download_file_object(self):
+        return self.object.open()
+
+    def get_download_label(self):
+        return force_text(self.object)
+
+
+class MultipleObjectDownloadView(
+    RestrictedQuerysetMixin, MultipleObjectMixin, BaseDownloadView
+):
+    """
+    View that support receiving multiple objects via a pk_list query.
+    """
+    def __init__(self, *args, **kwargs):
+        result = super(MultipleObjectDownloadView, self).__init__(*args, **kwargs)
+
+        if self.__class__.mro()[0].get_queryset != MultipleObjectDownloadView.get_queryset:
+            raise ImproperlyConfigured(
+                '%(cls)s is overloading the get_queryset method. Subclasses '
+                'should implement the get_source_queryset method instead. ' % {
+                    'cls': self.__class__.__name__
+                }
+            )
+
+        return result
+
+    def get_queryset(self):
+        try:
+            return super(MultipleObjectDownloadView, self).get_queryset()
+        except ImproperlyConfigured:
+            self.queryset = self.get_source_queryset()
+            return super(MultipleObjectDownloadView, self).get_queryset()
 
 
 class SingleObjectDynamicFormCreateView(

mayan/apps/common/mixins.py

@@ -13,6 +13,7 @@ from mayan.apps.acls.classes import ModelPermission
 from mayan.apps.acls.models import AccessControlList
 from mayan.apps.permissions import Permission
 
+from .compat import FileResponse
 from .exceptions import ActionError
 from .forms import DynamicForm
 from .literals import PK_LIST_SEPARATOR
@@ -56,6 +57,29 @@ class DeleteExtraDataMixin(object):
         return HttpResponseRedirect(redirect_to=success_url)
 
 
+class DownloadMixin(object):
+    as_attachment = True
+
+    def get_as_attachment(self):
+        return self.as_attachment
+
+    def get_download_file_object(self):
+        raise NotImplementedError(
+            'Class must provide a .get_download_file_object() method that '
+            'return a file like object.'
+        )
+
+    def get_download_filename(self):
+        return None
+
+    def render_to_response(self, **response_kwargs):
+        return FileResponse(
+            as_attachment=self.get_as_attachment(),
+            filename=self.get_download_filename(),
+            streaming_content=self.get_download_file_object()
+        )
+
+
 class DynamicFormViewMixin(object):
     form_class = DynamicForm
 
@@ -345,26 +369,6 @@ class ObjectNameMixin(object):
         return object_name
 
 
-# TODO: Remove this mixin and replace with restricted queryset
-class ObjectPermissionCheckMixin(object):
-    object_permission = None
-
-    def get_permission_object(self):
-        return self.get_object()
-
-    def dispatch(self, request, *args, **kwargs):
-        if self.object_permission:
-            AccessControlList.objects.check_access(
-                obj=self.get_permission_object(),
-                permissions=(self.object_permission,),
-                user=request.user
-            )
-
-        return super(
-            ObjectPermissionCheckMixin, self
-        ).dispatch(request, *args, **kwargs)
-
-
 class RedirectionMixin(object):
     action_cancel_redirect = None
     next_url = None

mayan/apps/common/tests/base.py

@@ -2,8 +2,6 @@ from __future__ import absolute_import, unicode_literals
 
 from django.test import TestCase
 
-from django_downloadview import assert_download_response
-
 from mayan.apps.acls.tests.mixins import ACLTestCaseMixin
 from mayan.apps.converter.tests.mixins import LayerTestCaseMixin
 from mayan.apps.permissions.tests.mixins import PermissionTestCaseMixin
@@ -14,7 +12,7 @@ from mayan.apps.user_management.tests.mixins import UserTestMixin
 
 from .mixins import (
     ClientMethodsTestCaseMixin, ConnectionsCheckTestCaseMixin,
-    ContentTypeCheckTestCaseMixin, ModelTestCaseMixin,
+    ContentTypeCheckTestCaseMixin, DownloadTestCaseMixin, ModelTestCaseMixin,
     OpenFileCheckTestCaseMixin, RandomPrimaryKeyModelMonkeyPatchMixin,
     SilenceLoggerTestCaseMixin, TempfileCheckTestCasekMixin,
     TestViewTestCaseMixin
@@ -22,7 +20,8 @@ from .mixins import (
 
 
 class BaseTestCase(
-    LayerTestCaseMixin, SilenceLoggerTestCaseMixin, ConnectionsCheckTestCaseMixin,
+    LayerTestCaseMixin, SilenceLoggerTestCaseMixin,
+    ConnectionsCheckTestCaseMixin, DownloadTestCaseMixin,
     RandomPrimaryKeyModelMonkeyPatchMixin, ACLTestCaseMixin,
     ModelTestCaseMixin, OpenFileCheckTestCaseMixin, PermissionTestCaseMixin,
     SmartSettingsTestCaseMixin, TempfileCheckTestCasekMixin, UserTestMixin,
@@ -31,7 +30,6 @@ class BaseTestCase(
     """
     This is the most basic test case class any test in the project should use.
     """
-    assert_download_response = assert_download_response
 
 
 class GenericViewTestCase(

mayan/apps/common/tests/mixins.py

@@ -18,12 +18,16 @@ from django.http import HttpResponse
 from django.template import Context, Template
 from django.test.utils import ContextList
 from django.urls import clear_url_caches, reverse
-from django.utils.encoding import force_bytes
+from django.utils.encoding import (
+    DjangoUnicodeDecodeError, force_bytes, force_text
+)
 from django.utils.six import PY3
 
 from mayan.apps.acls.classes import ModelPermission
 from mayan.apps.storage.settings import setting_temporary_directory
 
+from ..compat import FileResponse
+
 from .literals import (
     TEST_SERVER_HOST, TEST_SERVER_SCHEME, TEST_VIEW_NAME, TEST_VIEW_URL
 )
@@ -141,6 +145,37 @@ class ContentTypeCheckTestCaseMixin(object):
         self.client = CustomClient()
 
 
+class DownloadTestCaseMixin(object):
+    def assert_download_response(
+        self, response, content=None, filename=None, is_attachment=None,
+        mime_type=None
+    ):
+        self.assertTrue(isinstance(response, FileResponse))
+
+        if filename:
+            self.assertEqual(
+                response[
+                    'Content-Disposition'
+                ].split('filename="')[1].split('"')[0], filename
+            )
+
+        if content:
+            response_content = b''.join(list(response))
+
+            try:
+                response_content = force_text(response_content)
+            except DjangoUnicodeDecodeError:
+                """Leave as bytes"""
+
+            self.assertEqual(response_content, content)
+
+        if is_attachment is not None:
+            self.assertEqual(response['Content-Disposition'], 'attachment')
+
+        if mime_type:
+            self.assertTrue(response['Content-Type'].startswith(mime_type))
+
+
 class EnvironmentTestCaseMixin(object):
     def setUp(self):
         super(EnvironmentTestCaseMixin, self).setUp()