使用python GridFS检索文件元数据

Question

I am accessing GridFS using Python, and would like both access to a file and its metadata.

Python version is 2.7, MongoDB version is 3.0.7. OS is Ubuntu 14.04.

The file is stored as follows:

>>> fs = GridFS(db, "gridfstest")
>>> fs.put(
            "HELLO WORLD", 
             test_metadata ="testing", 
             other_metadata="other"
           )

And retrieved as follows:

>>> retrieved_file = fs.find_one()
>>> retrieved_file.read()
b'HELLO WORLD'
>>> print(retrieved_file.metadata)
None

I was expecting .metadata to be a dictionary of metadata. retrieved_file._file stores the metadata I was looking for, along with additional metadata, but I assume accessing anything beginning with an underscore is a hack at best.

So, how can I get the file and the metadata I originally set?

Answer 1

You metadata live in the files Collection which means in "gridfstest.files" so to retrieve your metadata you need to query that collection.

In [54]: col = db.gridfstest.files.findOne()

In [55]: col.find_one()
Out[55]: 
{'_id': ObjectId('5644e9220acf451b36f22438'),
 'chunkSize': 261120,
 'encoding': 'utf8',
 'length': 11,
 'md5': '361fadf1c712e812d198c4cab5712a79',
 'other_metadata': 'other',
 'test_metadata': 'testing',
 'uploadDate': datetime.datetime(2015, 11, 12, 19, 31, 46, 175000)}