Question

I have method like this , and want to return as Json , but it writes that Posts object is not Json serializable :S

def show_results_async(text):
   query  =  { '$or':[{'title':{'$regex':text}},{'author':{'$regex':text}} ]}
   posts = Posts.objects(__raw__=(query))
   return jsonify(result = posts)

Answer 1

tl,dr: There is no built-in function that’ll convert a MongoEngine document to JSON. So you’ll need to write your own.

In views.py:

def show_results_async(text):
   query  =  { '$or':[{'title':{'$regex':text}},{'author':{'$regex':text}} ]}
   posts = Posts.objects(__raw__=(query))
   return jsonify(result=posts.to_dict())

In post.py, add:

def to_dict(self):
   return helper.mongo_to_dict(self)

In helper.py:

def mongo_to_dict(obj):
    return_data = []

    if isinstance(obj, Document):
        return_data.append(("id",str(obj.id)))

    for field_name in obj._fields:

        if field_name in ("id",):
            continue

        data = obj._data[field_name]

        if isinstance(obj._fields[field_name], DateTimeField):
            return_data.append((field_name, str(data.isoformat())))
        elif isinstance(obj._fields[field_name], StringField):
            return_data.append((field_name, str(data)))
        elif isinstance(obj._fields[field_name], FloatField):
            return_data.append((field_name, float(data)))
        elif isinstance(obj._fields[field_name], IntField):
            return_data.append((field_name, int(data)))
        elif isinstance(obj._fields[field_name], ListField):
            return_data.append((field_name, data))
        elif isinstance(obj._fields[field_name], EmbeddedDocumentField):
            return_data.append((field_name, mongo_to_dict(data)))

    return dict(return_data)

A couple of notes:

• If your document has additional field types, you need to enhance the helper function above.
• The helper method above was inspired by Thomas’ answer to a question. Additional functionality includes: recursively print out EmbeddedDocuments and include the id of the document.