Develop Reference

Delete a list item from an Embedded Document MongoEngine

I'm having trouble to find the way to delete a list item inside an Embedded document using mongo engine.
Document structure:
{
"_id" : "id",
"user" : ObjectId("xxxxxxx"),
"invoice" : false,
"coupon" : ObjectId("xxxxxxx"),
"date" : ISODate("2017-03-31T11:32:57.467Z"),
"orders" : [
{
"products" : [
ObjectId("xxxxxxx")
]
}
],
"shipping_address" : {
},
}
Using this structure, what I want to achieve, is to delete the id inside the products list inside the orders embedded document.
Any idea? any help would be really appreciated

MongoEngine EmbeddedDocument query with array value

I have an object that looks something like this in the database, with corresponding MongoEngine models:
{
...
"config" : {
"inner_group" : {
"individuals" : [
{
"entity_id" : "54321",
}
],
},
...
}
...
}
I am trying to query this data using the entity_id field in the object which is part of the individuals collection.
I have tried querying according to the MongoEngine docs but I have not been able to pull the data using the following:
data = Model.objects(config__inner_group__individuals__S__entity_id="54321")
How can I query the entire parent based on the entity_id?

Pull from a list in a dict using mongoengine

I have this Document in mongo engine:
class Mydoc(db.Document):
x = db.DictField()
item_number = IntField()
And I have this data into the Document
{
"_id" : ObjectId("55e360cce725070909af4953"),
"x" : {
"mongo" : [
{
"list" : "lista"
},
{
"list" : "listb"
}
],
"hello" : "world"
},
"item_number" : 1
}
Ok if I want to push to mongo list using mongoengine, i do this:
Mydoc.objects(item_number=1).update_one(push__x__mongo={"list" : "listc"})
That works pretty well, if a query the database again i get this
{
"_id" : ObjectId("55e360cce725070909af4953"),
"x" : {
"mongo" : [
{
"list" : "lista"
},
{
"list" : "listb"
},
{
"list" : "listc"
}
],
"hello" : "world"
},
"item_number" : 1
}
But When I try to pull from same list using pull in mongo engine:
Mydoc.objects(item_number=1).update_one(pull__x__mongo={'list': 'lista'})
I get this error:
mongoengine.errors.OperationError: Update failed (Cannot apply $pull
to a non-array value)
comparising the sentences:
Mydoc.objects(item_number=1).update_one(push__x__mongo={"list" : "listc"}) # Works
Mydoc.objects(item_number=1).update_one(pull__x__mongo={"list" : "listc"}) # Error
How can I pull from this list?
I appreciate any help

I believe that the problem is that mongoengine doesn't know the structure of your x document. You declared it as DictField, so mongoengine thinks you are pulling from DictField not from ListField. Declare x as ListField and both queries should work just fine.
I suggest you should also create an issue for this:
https://github.com/MongoEngine/mongoengine/issues
As a workaround, you can use a raw query:
Mydoc.objects(item_number=1).update_one(__raw__={'$pull': {'x.mongo': {'list': 'listc'}}})

Dereference relations in MongoEngine embedded documents

I have a schema that using MongoEngine that looks like this
class User(db.Document)
email = db.EmailField(unique=True)
class QueueElement(db.EmbeddedDocument):
accepts = db.ListField(db.ReferenceField('Resource'))
user = db.ReferenceField(User)
class Resource(db.Document):
name = db.StringField(max_length=255, required=True)
current_queue_element = db.EmbeddedDocumentField('QueueElement')
class Queue(db.EmbeddedDocument):
name = db.StringField(max_length=255, required=True)
resources = db.ListField(db.ReferenceField(Resource))
queue_elements = db.ListField(db.EmbeddedDocumentField('QueueElement'))
class Room(db.Document):
name = db.StringField(max_length=255, required=True)
queues = db.ListField(db.EmbeddedDocumentField('Queue'))
and I would like to return a JSON object of a Room object that would include the information about its queues (together with the referenced resources), and the nested queue_elements ( together with their referenced "accepts" references, and user references)
However, when I want to return a Room with its relationships dereferenced:
room = Room.objects(slug=slug).select_related()
if (room):
return ast.literal_eval(room.to_json())
abort(404)
I don't get any dereferencing. I get:
{
"_cls":"Room",
"_id":{
"$oid":"552ab000605cd92f22347d79"
},
"created_at":{
"$date":1428842482049
},
"name":"second",
"queues":[
{
"created_at":{
"$date":1428842781490
},
"name":"myQueue",
"queue_elements":[
{
"accepts":[
{
"$oid":"552aafb3605cd92f22347d78"
},
{
"$oid":"552aafb3605cd92f22347d78"
},
{
"$oid":"552ab1f8605cd92f22347d7a"
}
],
"created_at":{
"$date":1428849389503
},
"user":{
"$oid":"552ac8c7605cd92f22347d7b"
}
}
],
"resources":[
{
"$oid":"552aafb3605cd92f22347d78"
},
{
"$oid":"552aafb3605cd92f22347d78"
},
{
"$oid":"552ab1f8605cd92f22347d7a"
}
]
}
],
"slug":"secondslug"
}
even though I'm using the select_related() function. I believe this is because MongoEngine may not follow references on embedded documents. Note, I can actually dereference in the python if I do something like this:
room = Room.objects(slug=slug).first().queues[0].queue_elements[0].accepts[0]
return ast.literal_eval(room.to_json())
which yields
{
"_id":{
"$oid":"552aafb3605cd92f22347d78"
},
"created_at":{
"$date":1428842849393
},
"name":"myRes"
}
which is clearly the dereferenced Resource document.
Is there a way I can follow references on embedded documents? Or is this coming up because I'm following a bad pattern, and should be finding a different way to store this information in MongoDB (or indeed, switch to a Relational DB) ? Thanks!

filtering query for django mongoengine

I have two views with embedded document and list field and need filteringquery
for below criteria:
class myfriends(EmbeddedDocument):
myfriends_ids = StringField()
status = StringField()
class Friends(Document):
friend1 = ReferenceField(User)
myfriendslist = ListField(EmbeddedDocumentField(myfriends))
And stored values just like:
{ "_id" : ObjectId("542506f9bed069156ddd4476"),
"friend1" : ObjectId("542314b7bed0691c5302662c"),
"myfriendslist" : [
{
"myfriends_ids" : "5421ae74bed0691471e95b92",
"status" : "1"
} ]
}
I want query to get specific record based on friend1 and myfriends_ids in django mongoengine.

Friends.objects(myfriendslist__match={"myfriends_ids": "5421ae74bed0691471e95b92", "status": "1"}, friend1=FriendObject)