正在更正scrip中的属性和/或UnboundLocalError

2024-03-28 22:24:49 发布

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这个脚本接受用户输入(对于雇员)并通过SQLAlchemy添加到sqlite3.db中。直到我在age字段的add\u data方法中添加了try: except子句(计划在其他字段中添加更多try/except子句)之后,它才正常工作。年龄字段必须是用户选择的整数。我意识到我需要一种方法来捕捉用户在字段中添加字符串而不是数字所导致的任何错误。相关代码。你知道吗

try:
        self.age = self.age_var.get()
    except ValueError:
        showinfo("Error:", "Please Enter A Number In Age Field.")

但是当我这样做的时候,它会产生一个问题,因为age现在变成了一个局部变量(正如回溯在另一篇文章中指出的),并且我得到了UnboundLocalError:在赋值之前引用的局部变量'age'。我尝试通过分离数据的检索和添加到数据库来更改代码,就像这样。你知道吗

def get_data(self):        
    self.name = self.name_var.get()
    try:
        self.age = self.age_var.get()
    except ValueError:
        showinfo("Error:", "Please Enter A Number In Age Field.")
    self.addr = self.address_var.get()
    self.city = self.city_var.get()
    self.state = self.state_var.get()
    self.zip = self.zip_var.get()   
    self.ssn = self.ssn_var.get()
    self.phone = self.phone_var.get()
    self.cell = self.cell_var.get()

def add_data(self):
    self.get_data()
    # create new Employee in .db
    new_person = Employee(name=self.name, age=self.age, address=self.addr, city=self.city, state=self.state, zip=self.zip, ssn=self.ssn, phone=self.phone, cell=self.cell)
    session.add(new_person)
    session.commit()
    session.close()
    self.callback()
    return

然而,我有同样的问题在不同的伪装。现在我得到了AttributeError: GUI instance has no attribute 'age'。我不知道如何避开这些问题。我尝试在try/except子句self.age=0之前为age添加一个默认值,它确实纠正了错误,但是产生了另一个问题。如果用户输入的是字符串而不是int,则showinfo框会显示警告,但当用户单击“确定”时,默认值“0”会自动添加到数据库中,而不是给用户再次输入年龄数字的机会。当然,我可以在类Employee中将age字段更改为字符串,但这不是我想要的。我不知道该怎么办。非常感谢您的帮助!不管怎样,这是原始代码。你知道吗

from datetime import datetime
from Tkinter import *
from tkMessageBox import *
import sqlite3, sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, DateTime, Integer, String, MetaData
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

# map classes to tables through Base Class
Base = declarative_base()


class Employee(Base):
    __tablename__ = 'employee'
    id = Column(Integer, primary_key=True)
    name = Column(String(250))
    age = Column(Integer)
    address = Column(String(250))
    city = Column(String(10))
    state = Column(String(2))
    zip = Column(Integer)
    ssn = Column(String(12))
    phone = Column(String(12))
    cell = Column(String(12))

# create engine for Session connection
engine = create_engine('sqlite:///employee.db')

# create all tables in engine ('CREATE TABLE' in raw SQL)
Base.metadata.create_all(engine)

# create configured 'Session' class
Session = sessionmaker(bind=engine)

# create session
session = Session()


class GUI:
    def __init__(self, parent):
        self.parent = parent

        # create top frame
        frame = Frame(parent)
        frame.pack(expand=YES, fill=BOTH, padx=5, pady=5)

        # create bottom frame
        btm_frame = Frame(parent, relief=SUNKEN, borderwidth=1)
        btm_frame.pack(side=BOTTOM, expand=YES, fill=BOTH, padx=5, pady=5)

        # create datetime object
        d = datetime.today()
        date = d.strftime("%Y-%m-%d")


#------------------------Create Labels-------------------------------#


        # label to display date
        date_label = Label(btm_frame, text=date)
        date_label.pack(side=LEFT)

        # name label
        name_label = Label(frame, text="Enter Name:")
        name_label.grid(row=0, sticky=W)

        # age label
        age_label = Label(frame, text="Enter Age:")
        age_label.grid(row=1, sticky=W)

        # address label
        addr_label = Label(frame, text="Enter Address:")
        addr_label.grid(row=2, sticky=W)

        # city label
        city_label = Label(frame, text="Enter City:")
        city_label.grid(row=3, sticky=W)

        # state label
        state_label = Label(frame, text="Enter State:")
        state_label.grid(row=4, sticky=W)

        # zip code label
        zip_label = Label(frame, text="Enter Zip Code:")
        zip_label.grid(row=5, sticky=W)

        # ssn label
        ssn_label = Label(frame, text="Enter Social Security #:")
        ssn_label.grid(row=6, sticky=W)

        # phone label
        phone_label = Label(frame, text="Enter Phone #:")
        phone_label.grid(row=7, sticky=W)

        # cell label
        cell_label = Label(frame, text="Enter Cell #:")
        cell_label.grid(row=8, sticky=W)


#----------------------Create Vars and Entry-------------------------#


        # name variable and entry
        self.name_var = StringVar()
        self.e1 = Entry(frame, textvariable=self.name_var)
        self.e1.grid(row=0, column=1)

        # age variable and entry
        self.age_var =  IntVar()
        self.e2 = Entry(frame, textvariable=self.age_var)
        self.e2.grid(row=1, column=1)

        # address variable and entry
        self.address_var = StringVar()
        self.e3 = Entry(frame, textvariable=self.address_var)
        self.e3.grid(row=2, column=1)

        # city variable and entry
        self.city_var = StringVar()
        self.e4 = Entry(frame, textvariable=self.city_var)
       self.e4.insert(0, "Roanoke")        # insert default value
       self.e4.grid(row=3, column=1)

        # state variable and entry
        self.state_var = StringVar()
        self.e5 = Entry(frame, textvariable=self.state_var)
        self.e5.insert(0, "VA")             # insert default value
        self.e5.grid(row=4, column=1)

        # zip code variable and entry
        self.zip_var = IntVar()
        self.e6 = Entry(frame, textvariable=self.zip_var)
        self.e6.grid(row=5, column=1)

        # s.s.n variable and entry
        self.ssn_var = StringVar()
        self.e7 = Entry(frame, textvariable=self.ssn_var)
        self.e7.grid(row=6, column=1)

    # phone variable and entry
        self.phone_var = StringVar()
        self.e8 = Entry(frame, textvariable=self.phone_var)
        self.e8.grid(row=7, column=1)

        # cell variable and entry
        self.cell_var = StringVar()
        self.e9 = Entry(frame, textvariable=self.cell_var)
        self.e9.grid(row=8, column=1)

        # quit, search, clear, add, delete buttons
        quit_button = Button(btm_frame, text="Quit", relief=GROOVE, command=parent.destroy)
        quit_button.pack(side=RIGHT)        

        search_button = Button(btm_frame, text="Search", relief=GROOVE, command=self.search)
        search_button.pack(side=RIGHT, padx=1, pady=1)

        clear_button = Button(btm_frame, text="Clear", relief=GROOVE, command=self.clear_entries)
        clear_button.pack(side=RIGHT, padx=1, pady=1)        

        del_button = Button(btm_frame, text="Delete", relief=GROOVE, command=self.del_employee)
        del_button.pack(side=RIGHT, padx=1, pady=1)

        add_button = Button(btm_frame, text="Add", relief=GROOVE, command=self.add_data)
        add_button.pack(side=RIGHT, padx=1, pady=1)


    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        

    def callback(self):        
        showinfo("New Employee", "Data Added")
        self.clear_entries()
        return        

    def clear_entries(self):
        entries = [self.e1, self.e2, self.e3, self.e4, self.e5, self.e6, self.e7, self.e8, self.e9]
        for entry in entries:
            entry.delete(0, END)
        return            

    def search(self):
        search_win = Toplevel()
        search_win.title("Employee Search")

        # create labels for each employee attribute
        attr =   ["Id","Name","Age","Address","City","State","Zip","SSN","Cell","Phone"]
        column = 0
        for a in attr:
                Label(search_win, text=a).grid(row=0,column=column,padx=2, pady=2)
                column += 1

        # search all employees, put each emp. in Entry Widget with For Loop
        res = session.query(Employee).all()
        row = 1
        column = 0
        for employee in res:
            txt = [employee.id, employee.name, employee.age, employee.address, employee.city, employee.state, employee.zip, employee.ssn, employee.phone, employee.cell]
            for t in txt:
                ent = Entry(search_win, relief=RIDGE, width=19)
                ent.grid(row=row, column=column, sticky=W, padx=1, pady=1)
                ent.insert(0, t)
                column += 1
            row += 1
            column = 0
        return

    def del_employee(self):
        del_win = Toplevel()
        del_win.title("Delete Employee")

        id_label = Label(del_win, text="Enter Employee Id:")
        id_label.grid(row=0, column=0, padx=5, pady=5)

        self.employee_id = IntVar()
        self.e10 = Entry(del_win, textvariable=self.employee_id)
        self.e10.grid(row=0, column=1, padx=5, pady=5)

        del_button = Button(del_win, text="Delete Employee", relief=GROOVE, command=self.erase)
        del_button.grid(row=0, column=2, padx=5, pady=5)
        return

    def erase(self):
        emp_id = self.employee_id.get()
        res = session.query(Employee).filter(Employee.id==emp_id).first()
        session.delete(res)
        session.commit()
        showinfo("Employee", "Data Deleted")
        return



if __name__ == '__main__':
    root = Tk()
    root.geometry("310x270")
    root.title("Employee Info")
    mygui = GUI(root)
    root.mainloop()

这是我在修改上面的代码后遇到的第一个错误,在add\u data方法中将try:except子句添加到age变量中。换句话说,将上面的add\u data方法更改为:

def add_data(self):        
    name = self.name_var.get()
    try:
        age = self.age_var.get()
    except ValueError:
        showinfo("Error:", "Please Enter A Number In Age Field.")
    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

当用户在“年龄”字段中输入一个字符串,然后单击showinfo对话框中的“确定”时,就会出现此错误):

    Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python27\lib\lib-tk\Tkinter.py", line 1532, in __call__
    return self.func(*args)
  File "C:\Python27\test2_gui.py", line 182, in add_data
    new_person = Employee(name=name, age=age, address=addr, city=city, state=state, zip=zip, ssn=ssn, phone=phone, cell=cell)
UnboundLocalError: local variable 'age' referenced before assignment

Tags: nameselfcityagegetvarphonecell
1条回答
网友
1楼 · 发布于 2024-03-28 22:24:49

在问题的开头有一段代码,后面加上“age现在变成局部变量”。这是不可能的,因为a)您显示的代码既不设置也不使用名为age的变量,b)try不是这样做的。您的代码设置了self.age,但这与名为age的局部变量完全不同。你知道吗

错误消息将告诉您所有需要知道的信息。如果它说“赋值前引用的局部变量‘age’”,那么你可以相信它说的是事实。你必须扪心自问:“为什么age不是self.age)是局部的,而我认为它是全局的?”,或“为什么我认为age没有设置?”。try语句本身不会神奇地使变量成为局部变量。

让我重复最后一行:try语句本身不会神奇地使变量成为局部变量。你在评论中链接到的另一个答案给了你不好的建议。你知道吗

理解正在发生的事情的一个简单的低技术方法是在分配局部变量age之后放置一个print语句,您将看到这行代码没有被执行。你需要通过你的逻辑来看看为什么它没有被执行。你知道吗

如果真正的问题是它在抱怨一个局部变量age,而您正在设置一个名为self.age的属性,那么问题就在于将age更改为self.age,然后再次在设置self.age的位置放置一个print语句,以在您得到错误之前向自己证明是否设置了它。你知道吗

不幸的是,你把问题弄得一团糟。我认为代码有两个不同的版本,错误消息与“原始版本”一起出现,与当前版本没有错误。我想。真的很难理解。你知道吗

问题很可能是,如果您的try在设置变量时发现错误,那么该变量就不会被设置。如果try后面有其他代码并使用该变量,则会失败,因为try块无法设置该变量。一个简单的解决方案可能是在catch块中将变量设置为零。你知道吗

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