Python 3.7.3 : Using the flask - part 018.

In this tutorial, I will show you how to fix auto increment in Flask SQLAlchemy.
The old source code for the user model from the server.py was this:

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    password = db.Column(db.String(120), unique=True)
    email = db.Column(db.String(120), unique=True)
    gender = db.Column(db.String(5), unique=True)
    work = db.Column(db.String(33), unique=True)
    city = db.Column(db.String(15), unique=True)

The server.sqlite will be this:

[mythcat@desk my_flask]$ sqlite3 server.sqlite 
SQLite version 3.26.0 2018-12-01 12:34:55
Enter ".help" for usage hints.
sqlite> .schema
CREATE TABLE user (
 id INTEGER NOT NULL, 
 username VARCHAR(80), 
 password VARCHAR(120), 
 email VARCHAR(120), 
 gender VARCHAR(5), 
 work VARCHAR(33), 
 city VARCHAR(15), 
 PRIMARY KEY (id), 
 UNIQUE (username), 
 UNIQUE (password), 
 UNIQUE (email), 
 UNIQUE (gender), 
 UNIQUE (work), 
 UNIQUE (city)
);
CREATE TABLE alembic_version (
 version_num VARCHAR(32) NOT NULL, 
 CONSTRAINT alembic_version_pkc PRIMARY KEY (version_num)
);
CREATE TABLE sqlite_stat1(tbl,idx,stat);
sqlite> ^Z 

If you want to change the id into auto increment then you need to follow this steps:

class User(db.Model):
    __tablename__ = 'user'
    __table_args__ = {'sqlite_autoincrement': True}
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    password = db.Column(db.String(120), unique=True)
    email = db.Column(db.String(120), unique=True)
    gender = db.Column(db.String(5), unique=True)
    work = db.Column(db.String(33), unique=True)
    city = db.Column(db.String(15), unique=True)

Delete the server.sqlite file or rename it.
Open python3 and create a new server.sqlite file:

[mythcat@desk my_flask]$ python3
Python 3.7.4 (default, Jul  9 2019, 16:32:37) 
[GCC 9.1.1 20190503 (Red Hat 9.1.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from server import db
>>> db.create_all()
>>> db.engine.table_names()
['sqlite_sequence', 'user']
>>> 
[5]+  Stopat                  python3 

Open the new file to see the changes:

[mythcat@desk my_flask]$ sqlite3 server.sqlite 
SQLite version 3.26.0 2018-12-01 12:34:55
Enter ".help" for usage hints.
sqlite> .schema
CREATE TABLE user (
 id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, 
 username VARCHAR(80), 
 password VARCHAR(120), 
 email VARCHAR(120), 
 gender VARCHAR(5), 
 work VARCHAR(33), 
 city VARCHAR(15), 
 UNIQUE (username), 
 UNIQUE (password), 
 UNIQUE (email), 
 UNIQUE (gender), 
 UNIQUE (work), 
 UNIQUE (city)
);
CREATE TABLE sqlite_sequence(name,seq);
sqlite>