Add file metadata app

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

mayan/apps/file_metadata/methods.py

@@ -0,0 +1,63 @@
+from __future__ import unicode_literals
+
+from django.utils.translation import ugettext_lazy as _
+
+from .events import event_file_metadata_document_version_submit
+from .tasks import task_process_document_version
+
+
+def method_document_submit(self):
+    latest_version = self.latest_version
+    # Don't error out if document has no version
+    if latest_version:
+        latest_version.submit_for_file_metadata_processing()
+
+
+def method_document_version_submit(self):
+    event_file_metadata_document_version_submit.commit(
+        action_object=self.document, target=self
+    )
+
+    task_process_document_version.apply_async(
+        kwargs={
+            'document_version_id': self.pk,
+        }
+    )
+
+
+def method_get_document_file_metadata(self, dotted_name):
+    latest_version = self.latest_version
+    # Don't error out if document has no version
+    if latest_version:
+        return latest_version.get_file_metadata(
+            dotted_name=dotted_name
+        )
+
+
+method_get_document_file_metadata.short_description = _(
+    'get_file_metadata(< file metadata dotted path >)'
+)
+method_get_document_file_metadata.help_text = _(
+    'Return the specified document file metadata entry.'
+)
+
+
+def method_get_document_version_file_metadata(self, dotted_name):
+    driver_internal_name, key = dotted_name.split('.')
+
+    try:
+        document_driver = self.file_metadata_drivers.get(
+            driver__internal_name=driver_internal_name
+        )
+    except self.file_metadata_drivers.model.DoesNotExist:
+        return
+    else:
+        try:
+            return document_driver.entries.get(key=key).value
+        except document_driver.entries.model.DoesNotExist:
+            return
+
+
+method_get_document_version_file_metadata.help_text = _(
+    'Return the specified document version file metadata entry.'
+)