updating EmbeddedDocument in Document with Flask - Mongoengine mongoengine.errors.OperationError

Question

I am developing a project with flask and mongodb(mongoengine drive). The application uses Note model as a embeddedDocument for User Modal.

class User(db.Document, UserMixin):
    fields like created_at, content, slug etc...
    notes = db.ListField(db.EmbeddedDocumentField('Note'))

class Note(db.Document):
     fields like created_at, content, slug, URLLink, isSecret etc...
     content = db.StringField(required=True)
     tags = db.ListField(db.StringField(required=True, max_length=20)

When I try to Update a Note it's okay, but then trying to append the updated note in the User collection I stucked!

views.py

@app.route("/update_quote/<string:id>" ,methods=['POST'])
@login_required
def update_quote(id):
    note = Note.objects(id=id).first()

    form = UpdateNoteForm()
    if request.method == 'POST':
        form = UpdateNoteForm(request.form)

        if form.validate == False:
            flash('Faliure','danger')
            return redirect(url_for('profile')+('/'+current_user.slug))

        if form.validate_on_submit():

            tags = form.tags2.data
            tagList = tags.split(",")

            note = Note.objects.get(id=form.wtf.data)
            note.update(content=form.content2.data, tags=tagList, URLLink=form.URLLink2.data)

            current_user.notes.append(note)
            current_user.update(notes__tags=tagList, notes__content=form.content2.data, notes__URLLink=form.URLLink2.data)

            flash("Success","success")

    return render_template("update.html", title="delete", form=form, note=note )

traceback

   mongoengine.errors.OperationError
OperationError: Update failed (cannot use the part (notes of notes.URLLink) to traverse the element ({notes: [ { _id: ObjectId('57d27bb24d2e9b04e175c0e5'), created_at: new Date(1473422818025), URLLink: "", content: "{
    "_id" : ObjectId("57d27b414d2e9b04d79883b3"),
    "created_at" : ISODate("2016-09-09T12:05:05.164Z"),
    "URLLink" : "",
    "content" : "c...", tags: [ "asd" ], isSecret: false, isArchived: false } ]}))

Traceback (most recent call last)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/flask_login.py", line 792, in decorated_view
return func(*args, **kwargs)
File "/Users/ozer/Google Drive/localhost/copylighter/views.py", line 225, in update_quote

                        note = Note.objects.get(id=form.wtf.data)
                        note.update(content=form.content2.data, tags=tagList, URLLink=form.URLLink2.data)

                        current_user.notes.append(note)
                        current_user.update(notes__tags=tagList, notes__content=form.content2.data, notes__URLLink=form.URLLink2.data)


                        #note.save()


File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/mongoengine/document.py", line 468, in update
return self._qs.filter(**self._object_key).update_one(**kwargs)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/mongoengine/queryset/base.py", line 490, in update_one
upsert=upsert, multi=False, write_concern=write_concern, **update)
File "/Users/ozer/Documents/localhost/copylighter/env/lib/python2.7/site-packages/mongoengine/queryset/base.py", line 472, in update
raise OperationError(u'Update failed (%s)' % unicode(err))
OperationError: Update failed (cannot use the part (notes of notes.URLLink) to traverse the element ({notes: [ { _id: ObjectId('57d27bb24d2e9b04e175c0e5'), created_at: new Date(1473422818025), URLLink: "", content: "{ "_id" : ObjectId("57d27b414d2e9b04d79883b3"), "created_at" : ISODate("2016-09-09T12:05:05.164Z"), "URLLink" : "", "content" : "c...", tags: [ "asd" ], isSecret: false, isArchived: false } ]}))

I think that's the important part that I writed below. I didn't find any quertset about it and there are few documentation about mongoengine. Where would I search for?

current_user.update(notes__tags=tagList, notes__content=form.content2.data, notes__URLLink=form.URLLink2.data)

score 0 · Answer 1 · edited May 23 '17 at 11:51

0

You have a few issues here:

You can use (in the most recent versions of mongoengine) an EmbeddedDocumentListField
The Noteclass needs to inherit EmbeddedDocument
You can't use an update operation on the User object in the way you are attempting

Consider the following example which will add a note to the users note field.

import mongoengine as mdb
from numpy.random.mtrand import randint

mdb.connect("embed-test")


class User(mdb.Document):
    name = mdb.StringField()
    notes = mdb.EmbeddedDocumentListField('Note')


class Note(mdb.EmbeddedDocument):
    content = mdb.StringField(required=True)
    tags = mdb.ListField(mdb.StringField(required=True, max_length=20))


User.drop_collection()

u = User(name="Name").save()

if __name__ == "__main__":
    new_note = Note(content="Some notes here.", tags=['one', 'two'])
    current_user = User.objects.first()
    current_user.notes.append(new_note)
    current_user.save()

You may also want to read this answer on when to you use EmbeddedDocument vs. a ReferenceField.

edited May 23 '17 at 11:51

Community

1
1

answered Sep 09 '16 at 10:50

Steve Rossiter

2,624
21
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Thank @steve-rossiter I maked the changes but still it returns the same error in traceback. – oyilmaztekin Sep 09 '16 at 11:45
Ok can you edit your answer to update it with the changes you've made? – Steve Rossiter Sep 09 '16 at 11:48
I am sorry I can't edit my answer. So I am writing in here. When I check my code for copy it for you I realise I wasn't change my Note modal class as class Note(db.EmbeddedDocument): I did this change but now I am working on inserting Note on the shell. http://prnt.sc/cfzmxa – oyilmaztekin Sep 09 '16 at 12:00
You don't need to save an EmbeddedDocument you just assign it to an EmbeddedDocumentField or append it to an EmbeddedDocumentListField – Steve Rossiter Sep 09 '16 at 12:07
Well, my whole development process crashed right now. I am struggling to change my point of view. Would you help me to understand what is that mean "assigning to EmbeddedDocumentField" or "appending to note EmbeddedDocumentListField" without saving it? – oyilmaztekin Sep 09 '16 at 12:14
1

Can I suggest you read the [user guide](http://docs.mongoengine.org/guide/index.html)? You will need to understand the fundamentals of how mongoengine maps from mongodb documents to python objects. – Steve Rossiter Sep 09 '16 at 12:31
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/122998/discussion-between-steve-rossiter-and-oyilmaztekin). – Steve Rossiter Sep 09 '16 at 13:10

updating EmbeddedDocument in Document with Flask - Mongoengine mongoengine.errors.OperationError

1 Answers1