Use python-magic to determine a document's mimetype otherwise fallback to use python's mimetypes library

apps/documents/models.py

@@ -7,13 +7,12 @@ from django.contrib.auth.models import User
 from django.contrib.contenttypes import generic
 from django.contrib.comments.models import Comment
 
-from python_magic import magic
-
 from taggit.managers import TaggableManager
 from dynamic_search.api import register
 from converter.api import get_page_count
 from converter import TRANFORMATION_CHOICES
 
+from documents.utils import get_document_mimetype
 from documents.conf.settings import CHECKSUM_FUNCTION
 from documents.conf.settings import UUID_FUNCTION
 from documents.conf.settings import STORAGE_BACKEND
@@ -117,22 +116,15 @@ class Document(models.Model):
     def update_mimetype(self, save=True):
         """
         Read a document's file and determine the mimetype by calling the
-        libmagic library
+        get_mimetype wrapper
         """
         if self.exists():
             try:
-                source = self.open()
+                self.file_mimetype, self.mime_encoding = get_document_mimetype(self)
-                mime = magic.Magic(mime=True)
-                self.file_mimetype = mime.from_buffer(source.read())
-                source.seek(0)
-                mime_encoding = magic.Magic(mime_encoding=True)
-                self.file_mime_encoding = mime_encoding.from_buffer(source.read())
             except:
                 self.file_mimetype = u''
                 self.file_mime_encoding = u''
             finally:
-                if source:
-                    source.close()
                 if save:
                     self.save()
 

apps/documents/utils.py

@@ -2,6 +2,14 @@ import os
 
 from common import TEMPORARY_DIRECTORY
 
+try:
+    from python_magic import magic
+    USE_PYTHON_MAGIC = True
+except:
+    import mimetypes
+    mimetypes.init()
+    USE_PYTHON_MAGIC = False
+
 
 #http://stackoverflow.com/questions/123198/how-do-i-copy-a-file-in-python
 def copyfile(source, dest, buffer_size=1024 * 1024):
@@ -29,3 +37,30 @@ def copyfile(source, dest, buffer_size=1024 * 1024):
 def document_save_to_temp_dir(document, filename, buffer_size=1024 * 1024):
     temporary_path = os.path.join(TEMPORARY_DIRECTORY, filename)
     return document.save_to_file(temporary_path, buffer_size)
+
+
+def get_document_mimetype(document):
+    """
+    Determine a documents mimetype by calling the system's libmagic
+    library via python-magic or fallback to use python's mimetypes
+    library
+    """
+    file_mimetype = u''
+    file_mime_encoding = u''    
+    
+    if USE_PYTHON_MAGIC:
+        if document.exists():
+            try:
+                source = document.open()
+                mime = magic.Magic(mime=True)
+                file_mimetype = mime.from_buffer(source.read())
+                source.seek(0)
+                mime_encoding = magic.Magic(mime_encoding=True)
+                file_mime_encoding = mime_encoding.from_buffer(source.read())
+            finally:
+                if source:
+                    source.close()
+    else:
+        file_mimetype, file_mime_encoding = mimetypes.guess_type(document.get_fullname())
+        
+    return file_mimetype, file_mime_encoding