Added a Django storage backend.

- New GridFSStorage storage backend
- New FileDocument document for storing files in GridFS
- Whitespace cleaned up in various files

mongoengine/django/storage.py

@@ -0,0 +1,112 @@
+import os
+import itertools
+import urlparse
+
+from mongoengine import *
+from django.conf import settings
+from django.core.files.storage import Storage
+from django.core.exceptions import ImproperlyConfigured
+
+
+class FileDocument(Document):
+    """A document used to store a single file in GridFS.
+    """
+    file = FileField()
+
+
+class GridFSStorage(Storage):
+    """A custom storage backend to store files in GridFS
+    """
+
+    def __init__(self, base_url=None):
+
+        if base_url is None:
+            base_url = settings.MEDIA_URL
+        self.base_url = base_url
+        self.document = FileDocument
+        self.field = 'file'
+
+    def delete(self, name):
+        """Deletes the specified file from the storage system.
+        """
+        if self.exists(name):
+            doc = self.document.objects.first()
+            field = getattr(doc, self.field)
+            self._get_doc_with_name(name).delete()  # Delete the FileField
+            field.delete()                          # Delete the FileDocument
+
+    def exists(self, name):
+        """Returns True if a file referened by the given name already exists in the
+        storage system, or False if the name is available for a new file.
+        """
+        doc = self._get_doc_with_name(name)
+        if doc:
+            field = getattr(doc, self.field)
+            return bool(field.name)
+        else:
+            return False
+
+    def listdir(self, path=None):
+        """Lists the contents of the specified path, returning a 2-tuple of lists;
+        the first item being directories, the second item being files.
+        """
+        def name(doc):
+            return getattr(doc, self.field).name
+        docs = self.document.objects
+        return [], [name(d) for d in docs if name(d)]
+
+    def size(self, name):
+        """Returns the total size, in bytes, of the file specified by name.
+        """
+        doc = self._get_doc_with_name(name)
+        if doc:
+            return getattr(doc, self.field).length
+        else:
+            raise ValueError("No such file or directory: '%s'" % name)
+
+    def url(self, name):
+        """Returns an absolute URL where the file's contents can be accessed
+        directly by a web browser.
+        """
+        if self.base_url is None:
+            raise ValueError("This file is not accessible via a URL.")
+        return urlparse.urljoin(self.base_url, name).replace('\\', '/')
+
+    def _get_doc_with_name(self, name):
+        """Find the documents in the store with the given name
+        """
+        docs = self.document.objects
+        doc = [d for d in docs if getattr(d, self.field).name == name]
+        if doc:
+            return doc[0]
+        else:
+            return None
+
+    def _open(self, name, mode='rb'):
+        doc = self._get_doc_with_name(name)
+        if doc:
+            return getattr(doc, self.field)
+        else:
+            raise ValueError("No file found with the name '%s'." % name)
+
+    def get_available_name(self, name):
+        """Returns a filename that's free on the target storage system, and
+        available for new content to be written to.
+        """
+        file_root, file_ext = os.path.splitext(name)
+        # If the filename already exists, add an underscore and a number (before
+        # the file extension, if one exists) to the filename until the generated
+        # filename doesn't exist.
+        count = itertools.count(1)
+        while self.exists(name):
+            # file_ext includes the dot.
+            name = os.path.join("%s_%s%s" % (file_root, count.next(), file_ext))
+
+        return name
+
+    def _save(self, name, content):
+        doc = self.document()
+        getattr(doc, self.field).put(content, filename=name)
+        doc.save()
+
+        return name