Can't save Document once a new field added to the sub document. referenced using EmbeddedDocumentListField

Question

I'm having a document and its sub-document, which works fine without changing anything which exists. When I add new field to the sub-document, while saving I got "you can only reference documents once they have been saved to the database"

class SkillDetail(EmbeddedDocument):
    SkillName = StringField()
    EnrollDate = DateField()
    #newfield = ListField()

class Skills(Document):
    id = IntField()
    Name = StringField()
    SkillsDetails = EmbeddedDocumentField(SkillDetail)

    def update_method(self, skillNamevalue, enrolldate, newFieldValues):
        self.SkillsDetails.append(
            SkillDetail(SkillName=skillNamevalue, EnrollDate=enrolldate, newfield=newFieldValues))
        self.save()

which actually works fine without the newfield in embedded document. But, when I add the newfield (highlighted field in the SkillDetail document) and run the program I got the error mentioned above.

NOTE: actually im calling update_method() method in the Skills class to assign values to the embedded document

kindly help me to solve this problem thanks in advance

The code snippet is poor (indentation wrong, typos) and is not complete (e.g: there is no self defined in your example), please provide a reproducible snippet. — bagerard, Sep 18 '19 at 06:34
@bagerard now I've provided enough information on the question. Please give some advice to proceed further with this. MY work got stopped due to this issue. — Gopi P, Sep 19 '19 at 04:36

score 0 · Answer 1 · answered Sep 19 '19 at 09:32

I had to fix a few things in your code (e.g make id primary key, make SkillsDetails a EmbeddedDocumentListField) but the following works for me:

from mongoengine import *
import datetime as dt

conn = connect()

class SkillDetail(EmbeddedDocument):
   skill_name = StringField()
   enroll_date = DateField()
   newfield = ListField()

class Skills(Document):
   id = IntField(primary_key=True)
   name = StringField()
   skills_details = EmbeddedDocumentListField(SkillDetail)

   def update_method(self, skill_name, enroll_date, new_field_values):
       self.skills_details.append(SkillDetail(skill_name = skill_name, enroll_date=enroll_date, newfield = new_field_values))
       self.save()

sk = Skills(id=1, name='myname')
sk.update_method('a', dt.datetime.utcnow(), [1,2])

existing_sk = Skills.objects.first()
existing_sk.newfield
print(existing_sk.skills_details[0].newfield) # prints "[1, 2]"

Can't save Document once a new field added to the sub document. referenced using EmbeddedDocumentListField

1 Answers1