Error getting MongoDB by _Id in Flask - mongodb

Question

I can query my MongoDB and I see the "_id" value like this:
"_id" : BinData(3,"sFgVQWMKzUiWl5dql62j2g==")
Using Flask 0.10.1 and PyMongo 3.0.3 I attempt to "find_one" like this:
record = db.collection.find_one({'_id': ObjectId("sFgVQWMKzUiWl5dql62j2g==")})
And I get this error:
bson.errors.InvalidId: 'sFgVQWMKzUiWl5dql62j2g==' is not a valid ObjectId, it must be a 12-byte input or a 24-character hex string
Any help would be appreciated.

Answer 1

Try this:
record = db.collection.find_one({'_id': BinData(3, "sFgVQWMKzUiWl5dql62j2g==")})

Answer 2

Ok here is how I got this working. From my PyMongo client I queried the result and got this:
_id: "497ffaf0-5ed3-3a4e-99ae-6b5c5f9b431e"
Note how that is not like the MongoDB console client which returns this:
_id : BinData(3,"sFgVQWMKzUiWl5dql62j2g==")
So seeing that the value looked like a GUID I started digging around and found that is a UUID and with that I did this:
import uuid
record = db.collection.find_one({'_id': uuid.UUID("497ffaf0-5ed3-3a4e-99ae-6b5c5f9b431e")})
This worked! Hazzah.

Answer 3

You are storing _id as bindata and trying to retrive it as ObjectId,
instead of ObjectId.
First you need to convert your base64string to binary and then try to search.
bi = binary.Binary("sFgVQWMKzUiWl5dql62j2g==");
record = db.collection.find_one({'_id': bi});
This will work for you.
It will convert your id to binary then compare to get result.

Answer 4

Using Flask, MongoEngine I also was receiving errors searching by _id: mongoengine.errors.ValidationError: "DBRef('m_turk', ObjectId('5966b478b929570647f51a5c'))" is not a valid ObjectId, it must be a 12-byte input or a 24-character hex string
In my case, the object id from MongoEngine.Document is of type bson.dbref.DBREF, whereas MongoEngine.Document expects type bson.objectid.ObjectId, despite returning bson.dbref.DBREF on MongoEngine.Document.objects(...).*. I'm not sure if this is an API inconsistency or simply my fault.
The fix was:
from flask_mongoengine import MongoEngine
from bson.objectid import ObjectId
... set Flask up ...
db = MongoEnginee(app)
class MiniFoo(db.Document):
foo = db.StringField()
class MyDoc(db.Docment):
key = db.StringField()
myself = db.ReferenceField(MiniFoo)
other_foos = db.ReferenceField(MiniFoo)
myobj = MyDoc.objects.get(key="over the rainbow")
# want to find other foos!
# Will fail with exception above
try:
MiniFoo.objects.with_id(myobj.other_foos[0].id)
except:
MiniFoo.objects.with_id(ObjectId(obj.id))

Answer 5

with MongoEngine
from flask_mongoengine import MongoEngine
from bson.objectid import ObjectId
db = MongoEngine()
db.init_app(app)
class Model(db.Document):
_id = db.ObjectIdField()
name = db.StringField(required=True)
#classmethod
def findById(cls, _id: str):
return cls.objects(_id=ObjectId(_id)).first()
modelById = Model.findById('601ec2d13ad7559bf7ebad76')