flask chained dropdown with selectfield Not a valid choice
You must also fill in the form.area.choices before validation. Or else there is no valid choice for area ... and so you've got an error message if your form provide one.
@users.route("/finish_registration", methods=['GET', 'POST'])def finish_registration(): cur = mysql.connection.cursor() result1 = cur.execute("select * from region") results = cur.fetchall() form = RegistrationDDForm(request.form) form.region.choices = [('0', 'Select Region')] + [(x['region_id'], x['region']) for x in results] if request.method == 'POST': cur = mysql.connection.cursor() results = cur.execute("select * from area where region_id=%s", request.form.region_id) results = cur.fetchall() # Add choices to area to allow validation form.area.choices = [(x['area_id'], x['area']) for x in results] if form.validate(): # Eventually add data to database table pass return render_template('finish_registration.html', title='Register', form=form)