How to fix 'list index out of range' error in python?

Question

I'm setting up the RFID reader for the attendance system. But when I place my tag to the reader, it was interrupted with the Tag id - which I externally stored to a database.

#//////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

Arben John Avillanosa · Accepted Answer · 2019-05-28 09:26:13Z

2

Your code structure is not correct. Try to indent rdr.anticoll() with this whenever the tag request is incorrect no process will occur.

Try the line of codes for better visualization:

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")

edited May 28, 2019 at 9:26

answered May 28, 2019 at 9:20

Arben John Avillanosa

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3 Comments

Arben John Avillanosa Over a year ago

The thing is whenever the tag is incorrect instead of not processing the incorrect request it still process that incorrect request

Dilux Over a year ago

Still, I have the same error [tap_id = str(uid[0])+str(uid[1])+str(uid[2])+str(uid[3]) IndexError: list index out of range]

Arben John Avillanosa Over a year ago

Try to print the length of uid. I think the fetched data is not enough

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