How to get subfield value in mongo base when using flask-admin?

Question

MongoDB

I have a mongo base with the following structure:

{
    card: {
            title: {
                type: String,
                default: "Course title"
            }
    }
}

I connected using pymongo and tried to write to the database, but it didn't work out what I wanted:

{
    {   
        "title": "fgd"
    }
}

Here is my code:

conn = pymongo.MongoClient(uri)
db = conn.get_default_database()
class CoursesForm(form.Form):   
    title = fields.TextField('Title')    
class CoursesView(ModelView):  
    column_list = ('title')    
    form = CoursesForm

Please tell me how to fix this error?