How to fetch existing table from database using sqlalchemy in python?

Question

I have 'device' table in my database, I am trying to fetch the that device object so i can update some record to that table . I have tried meta = MetaData(bind=engine, reflect=True) its working fine but showing some warning "SADeprecationWarning: The MetaData.reflect flag is deprecated and will be removed in a future release. Please use the MetaData.reflect() method." When i am trying with MetaData.reflect() not getting the expected output .

from sqlalchemy import create_engine, inspect
from sqlalchemy.orm import sessionmaker
from sqlalchemy.engine.url import URL
from sqlalchemy import MetaData

db_url = {
         'drivername': 'postgres',
          'username': 'postgres',
          'password': '***',
          'host': 'localhost',
        'database': "test_db",
          'port': 5432}
engine = create_engine(URL(**db_url))
session_obj = sessionmaker(bind=engine)
meta = MetaData().reflect(bind=engine)
print(meta)
user_t = meta.tables['device']
sel_st = user_t.select()
conn = engine.connect()
res = conn.execute(sel_st)
for _row in res:
    print(_row)

Let me know what i am missing .

meta = MetaData(), then meta.reflect(bind=engine). Now you bind the return value of reflect(), which is probably None. It is common in Python that methods that mutate the object return None: stackoverflow.com/questions/11205254/… — Ilja Everilä
– Ilja Everilä, Commented Mar 4, 2020 at 14:03
@IljaEverilä yeah that's correct. But do you know how to implement the above scenario ? — Vivek Kumar
– Vivek Kumar, Commented Mar 5, 2020 at 5:03

xariasu · Accepted Answer · 2020-11-12 11:48:36Z

2

change this line

meta = MetaData().reflect(bind=engine)
print(meta)
user_t = meta.tables['device']

into

meta = MetaData()
meta.reflect(bind=engine)
user_t= meta.tables.get('device')

answered Nov 12, 2020 at 11:48

xariasu

212 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user14520680 Over a year ago

Welcome to Stackoverflow! When answering a question, try to explain what you are trying to achieve in your answer. Code only answers do not help the OP as much as code answers with explanations because the OP understands why they must do what you have done.

Collectives™ on Stack Overflow

How to fetch existing table from database using sqlalchemy in python?

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related