Mongoengine：为什么to_json返回$ oid或$ date键？

Question

Using python and mongodb with mongoengine, I wonder why "to_json" function doesn't work as excepted.

For exemple,with "Comments" as a Document, comments. to_json() returns me :

  {
  "_id": {
    "$oid": "53eb97a312f8035580b92241"
  },
  "created": {
    "$date": 1407955862027
  }

And I except to get :

  {
  "_id":"53eb97a312f8035580b92241",
  "created": 1407955862027
  }

Do I really need to parse all the json data to get what I want ?

Answer 1

JSON supports simple datatypes only and as such there is no native JSON support for ObjectId's or for dates. BSON the binary json supertype that MongoDB stores its data in has support for more datatypes.

To allow lossless BSON -> JSON -> BSON conversion there is an extended json format and this is what MongoEngine uses.