Adding a document in Mongoengine
To add a document in Mongoengine, you first need to define a document class that inherits from the Document class provided by Mongoengine. You can then create an instance of this class and populate it with the necessary data. Finally, you can call the save() method on the instance to save it to the database. Here's an example:
```python
from mongoengine import Document, StringField
class User(Document):
name = StringField(required=True)
# Create a new User document
new_user = User(name="John Doe")
new_user.save()
```
Updating a reference field in another document
When you want to update a reference field in another document in Mongoengine, you first need to retrieve the document that contains the reference field. You can then update the reference field with the new value and call the save() method on the document to save the changes to the database. Here's an example:
```python
from mongoengine import ReferenceField
class Post(Document):
title = StringField(required=True)
author = ReferenceField(User)
# Retrieve a Post document
post = Post.objects.first()
# Update the reference field with the new User instance
post.author = new_user
post.save()
```
In this example, we first retrieve a Post document from the database and then update the author reference field with the new User instance that we created earlier. Finally, we call the save() method on the Post document to save the changes to the database.