class MyUser (Model):
   name=TextField()
   city=TextField()
   age=IntegerField(constraints=[Check('name<10')])
   class Meta:
      database=db
      db_table='MyUser'

CREATE TABLE MyUser (
   id INTEGER NOT NULL
   PRIMARY KEY,
   name TEXT NOT NULL,
   city TEXT NOT NULL,
   age INTEGER NOT NULL
   CHECK (name < 10)
);

MyUser.create(name="Rajesh", city="Mumbai",age=9)
peewee.IntegrityError: CHECK constraint failed: MyUser

city=TextField(constraints=[SQL("DEFAULT 'Mumbai'")])