On 2015-03-18 02:41, Chris Kavanagh wrote:
I have a simple script that takes user input (for an Employee) such as
name, age, etc then puts in an sqlite3 database. The script worked fine
until I realized one problem. The age input field is defined in
SQLAlchemy as an Integer, so if a user inputs a string instead of a
number in that field, an error will occur (in IDLE). . .
So, I put a try: except clause in the code for the age field in the
add_data method. . .
try:
age = self.age_var.get()
except ValueError:
showinfo("Error:", "Please Enter A Number In Age Field.")
If the user inputs a string (instead of an Int) the showinfo dialogue
box opens as it should, but when the user clicks "ok" in the box, I get
the error "UnboundLocalError: local variable 'age' referenced before
assignment". I tried using a default value above the try: except clause
(age=0), which corrects the error, but causes "0" to be saved in the
database instead of letting the user choose another value. I want to
figure why I get the error (with the try: except clause) and what
exactly to do about it. Thanks in advance for any help!
Here's the original code (without the try: except clause above). . .Just
put the try: except clause in the age variable in the add_data method as
shown above to get the error.
[snip]
def add_data(self):
name = self.name_var.get()
age = self.age_var.get()
addr = self.address_var.get()
city = self.city_var.get()
state = self.state_var.get()
zip = self.zip_var.get()
ssn = self.ssn_var.get()
phone = self.phone_var.get()
cell = self.cell_var.get()
# create new Employee in .db
new_person = Employee(name=name, age=age, address=addr,
city=city, state=state, zip=zip, ssn=ssn, phone=phone, cell=cell)
session.add(new_person)
session.commit()
session.close()
self.callback()
return
Try stepping through the method in your head.
What happens if the user enters a non-number? A ValueError exception
occurs. You catch that, show a dialog, but then continue on with the
remainder of the method.
Because of the exception, you haven't assigned to 'age', hence the
UnboundLocalError exception.
If you assign a default value to age, it'll continue on to where you
put it into the database.
Why not just return from the method after showing the dialog?
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