GridFS

New in version 0.4.

Writing

GridFS support comes in the form of the FileField field object. This field acts as a file-like object and provides a couple of different ways of inserting and retrieving data. Arbitrary metadata such as content type can also be stored alongside the files. In the following example, a document is created to store details about animals, including a photo:

class Animal(Document):
    genus = StringField()
    family = StringField()
    photo = FileField()

marmot = Animal('Marmota', 'Sciuridae')

marmot_photo = open('marmot.jpg', 'r')      # Retrieve a photo from disk
marmot.photo = marmot_photo                 # Store photo in the document
marmot.photo.content_type = 'image/jpeg'    # Store metadata

marmot.save()

Another way of writing to a FileField is to use the put() method. This allows for metadata to be stored in the same call as the file:

marmot.photo.put(marmot_photo, content_type='image/jpeg')

marmot.save()

Retrieval

So using the FileField is just like using any other field. The file can also be retrieved just as easily:

marmot = Animal.objects(genus='Marmota').first()
photo = marmot.photo.read()
content_type = marmot.photo.content_type

Streaming

Streaming data into a FileField is achieved in a slightly different manner. First, a new file must be created by calling the new_file() method. Data can then be written using write():

marmot.photo.new_file()
marmot.photo.write('some_image_data')
marmot.photo.write('some_more_image_data')
marmot.photo.close()

marmot.photo.save()

Deletion

Deleting stored files is achieved with the delete() method:

marmot.photo.delete()

Note

The FileField in a Document actually only stores the ID of a file in a separate GridFS collection. This means that Animal.drop_collection() will not delete any files. Care should be taken to manually remove associated files before dropping a collection.

Replacing files

Files can be replaced with the replace() method. This works just like the put() method so even metadata can (and should) be replaced:

another_marmot = open('another_marmot.png', 'r')
marmot.photo.replace(another_marmot, content_type='image/png')

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