如何修复python中的'list index out of range‘错误？

Question

我正在设置考勤系统的RFID阅读器。但是当我把我的标签放到阅读器上时，它被标签id中断了-我把它外部存储到数据库中。

#//////place your tag//////

print("Now place your tag to write")
rdr.wait_for_tag()

(error, data) = rdr.request()
if not error:
    print("\nDetected: " + format(data, "02x"))

(error, uid) = rdr.anticoll()
if not error:
    print("Card read UID: " +str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]))

tagid = str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]) 

print("Written..!")
print(tagid)


cursor.execute("insert into rfid_check (uid,firstname,age,tag_id) values ('%s','%s','%s','%s')" %(user_id,fname, ag_e, tagid))
connection.commit()
print("Data was successfully Added...!")

tagid = str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]) 
IndexError: list index out of range

Answer 1

代码结构不正确。尝试用这个来缩进rdr.anticoll()，只要标记请求不正确，就不会发生任何处理。

尝试下面这行代码，以获得更好的可视化效果：

print("Now place your tag to write")
rdr.wait_for_tag()

(error, data) = rdr.request()
if not error:
    print("\nDetected: " + format(data, "02x"))

    (error, uid) = rdr.anticoll()
    if not error:
        print("Card read UID: " +str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]))

        tagid = str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]) 

        print("Written..!")
        print(tagid)
        cursor.execute("insert into rfid_check (uid,firstname,age,tag_id) values ('%s','%s','%s','%s')" %(user_id,fname, ag_e, tagid))
        connection.commit()
        print("Data was successfully Added...!")
else:
    print("Unsuccessful")