How to update SQLAlchemy row entry

Question

Assume table has three columns  username  password and no of logins   When user tries to login  it s checked for an entry with a query like  user   User query filter by username form username data  first     If password matches  he proceeds further  What I would like to do is count how many times the user logged in  Thus whenever he successfully logs in  I would like to increment the no of logins field and store it back to the user table  I m not sure how to run update query with SqlAlchemy

User · Accepted Answer

user no of logins    1 session commit

User · Answer

With the help of user User query filter by username form username data  first   statement you will get the specified user in user variable    Now you can change the value of the new object variable like user no of logins    1 and save the changes with the session s commit method

User · Answer

I wrote telegram bot  and have some problem with update rows   Use this example  if you have Model  def update state chat id  state       try          value   Users query filter Users chat id    str chat id   first           value state   str state          db session flush           db session commit            db session close       except          print  Error in def update state     Why use db session flush    That s why     SQLAlchemy  What  39 s the difference between flush   and commit

User · Answer

There are several ways to UPDATE using sqlalchemy  1  user no of logins    1    session commit    2  session query            filter User username    form username data           update   no of logins    User no of logins  1       session commit    3  conn   engine connect      stmt   User update            values no of logins  User no of logins   1            where User username    form username data     conn execute stmt   4  setattr user   no of logins   user no of logins 1     session commit

User · Answer

Examples to clarify the important issue in accepted answer s comments  I didn t understand it until I played around with it myself  so I figured there would be others who were confused as well   Say you are working on the user whose id    6 and whose no of logins    30 when you start     1  bad  user no of logins    1   result  UPDATE user SET no of logins   31 WHERE user id   6    2  bad  user no of logins   user no of logins   1   result  UPDATE user SET no of logins   31 WHERE user id   6    3  bad  setattr user   no of logins   user no of logins   1    result  UPDATE user SET no of logins   31 WHERE user id   6    4  ok  user no of logins   User no of logins   1   result  UPDATE user SET no of logins   no of logins   1 WHERE user id   6    5  ok  setattr user   no of logins   User no of logins   1    result  UPDATE user SET no of logins   no of logins   1 WHERE user id   6   The point  By referencing the class instead of the instance  you can get SQLAlchemy to be smarter about incrementing  getting it to happen on the database side instead of the Python side   Doing it within the database is better since it s less vulnerable to data corruption  e g  two clients attempt to increment at the same time with a net result of only one increment instead of two    I assume it s possible to do the incrementing in Python if you set locks or bump up the isolation level  but why bother if you don t have to   A caveat  If you are going to increment twice via code that produces SQL like SET no of logins   no of logins   1  then you will need to commit or at least flush in between increments  or else you will only get one increment in total     6  bad  user no of logins   User no of logins   1 user no of logins   User no of logins   1 session commit     result  UPDATE user SET no of logins   no of logins   1 WHERE user id   6    7  ok  user no of logins   User no of logins   1 session flush     result  UPDATE user SET no of logins   no of logins   1 WHERE user id   6 user no of logins   User no of logins   1 session commit     result  UPDATE user SET no of logins   no of logins   1 WHERE user id   6

[python] How to update SQLAlchemy row entry?

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