error while inserting values into a table from form in flask in postgreSQL

[sahilsiddharth]

my question here
forms.py---

class SignUpForm(Form):
first_name = StringField('First name', validators=[DataRequired("Please enter your first name")])
last_name = StringField('Last name', validators=[DataRequired("Please enter your last name")])
email = StringField('email', validators=[DataRequired("Please enter valid email address"), Email("Enter valid email address")])
password = PasswordField('password', validators=[DataRequired("Please enter your password"),Length(min=6, message="Password must be minimum 6 characters")])
submit=SubmitField('Sign Up')

python code -  

     newuser = USERS(form.first_name.data, form.last_name.data, form.email.data, form.password.data )
     db.session.add(newuser)
     db.session.commit()
     return 'Success!'

Error --

Error:
sqlalchemy.exc.IntegrityError
sqlalchemy.exc.IntegrityError: (psycopg2.IntegrityError) null value in column "FIRST_NAME" violates not-null constraint
DETAIL:  Failing row contains (11, null, null, null, null).
[SQL: 'INSERT INTO "USERS" ("FIRST_NAME", "LAST_NAME", "EMAIL_ID", "PWDHASH") VALUES (%(FIRST_NAME)s, %(LAST_NAME)s, %(EMAIL_ID)s, %(PWDHASH)s) RETURNING "USERS"."USER_ID"'] [parameters: {'FIRST_NAME': None, 'LAST_NAME': None, 'EMAIL_ID': None, 'PWDHASH': None}]

[nilamo]

sqlalchemy.exc.IntegrityError: (psycopg2.IntegrityError) null value in column "FIRST_NAME" violates not-null constraint

Don't insert nulls. You're welcome :)

[snippsat]

class SignUpForm(Form):

Flask-WTF has changes Form to FlaskForm.
Then not getting any values from client side form submit and insert to PostgreSQL will be wrong.
class SignUpForm(FlaskForm):

[sahilsiddharth]

After changing from Form to FlaskForm , getting same error . I can print the value of form.first_name.data, form.last_name.data, form.email.data, form.password.data but when it is going to add into the table , giving error .

Do i have to do migration in Flask like we have to do in django.