Updates to JSON field don't persist to DB

If you are using Postgres < 9.4 you can't update JSON field directly. You need flag_modified function to report the change to SQLAlchemy:

from sqlalchemy.orm.attributes import flag_modified
model.data['key'] = 'New value'
flag_modified(model, "data")
session.add(model)
session.commit()

I'm using JSON field and I referred below document.

https://docs.sqlalchemy.org/en/13/core/type_basics.html?highlight=json#sqlalchemy.types.JSON

It shows how to make JSON-dict field mutable. (Default is immutable)

like this..

from sqlalchemy.ext.mutable import MutableDict
from sqlalchemy import Column, Integer, JSON

class TableABC(Base):
    __tablename__ = 'table_abc'
    id = Column(Integer, primary_key=True)
    info = Column(MutableDict.as_mutable(JSON))

Then I could update json field as ORM.

My issue was referencing the row object returned from SQLAlchemy when creating the new row. e.g. this does not work:

row = db.session.query(SomeTable).filter_by(id=someId).first()
print(row.details)
newDetails = row.details
newDetails['key'] = 'new data'
row.details = newDetails
db.session.commit()

but creating a new dict does work

row = db.session.query(SomeTable).filter_by(id=someId).first()
print(row.details)
newDetails = dict(row.details)
newDetails['key'] = 'new data'
row.details = newDetails
db.session.commit()

notice dict(row.details)