SqlAlchemy(Flask+Postgres) : How to update only a specific attribute of a json field?

I have a table that has one column declared as a json and I need to update records by adding a key-value to the json value.

model

class User(db.Model):

    __tablename__ = 'users'

    loginId         = db.Column(db.String(128),  nullable=False, primary_key=True)
    _password       = db.Column(db.String(128),  nullable=True)
    views           = db.Column(JSON,         nullable=True)

controller

@mod_event.route('/view', methods=['POST'])
def view():
    try:
        params = request.json
        loginId = params['dream']['loginId']
        users.update().\
            where(users.c.loginId==loginId).\
            values(views=<query>))

Assume current value in views is {'1001' : 1} What should be the query if views has to be updated to -

• {'1001' : 2}
• {'1001' : 1, '1002' : 1}

if i don't want to query the value first, change and update back.

I'm having a hard time figuring how to do this in a single query, please help, thanks!