NDB JsonProperty and Cloud Datastore library compatibility

Question

I have code running on Standar GAE using NDB and code running in flexible env using Google Cloud datastore library. Both accessing to the same entities.

I have problems dealing with ndb.JsonProperty. As far as I read those properties are stored as blob, so I tried to simulate that property using cloud library. Before store the value I do the following:

value_to_store = json.dumps(value, separators=[',',':'])
value_to_store = base64.b64encode(value_to_store)

And the opposite when I read a property:

read_value = base64.b64decode(from_db_value)
read_value = json.loads(read_value)

Everything works fine in this situations:

Insert using NDB ---> Read using Cloud Library
Insert using Cloud Library ---> Read using Cloud Library

But fails when:

Insert using Cloud Library --> Read using NDB

What's the right way to store those kind of properties to make them compatibles with NDB?

Thanks.

Answer 1

Finally I found the solution.

The point is that NDB is storing the value as blob while the library is storing as string.

The solution is just do not encode/decode the string value, the library will do it and will store the value as blob, that is what NDB expects.

Writing:

value_to_store = json.dumps(value, separators=[',',':'])

Reading:

read_value = json.loads(read_value)

Easy!