I'm looking to make a library type program that allows you to take out a book from a small "database" text file, and then amend the line in the file to include the user ID previously entered to show that it's taken.
The user ID when entered has to be an integer and 4 digits long, which I've got the program to work out with a try/except, except now when it comes to moving on to actually write the file, it no longer seems to run past asking for the book_id although it was functional before I put in everything checking for the right length of ID.
Also this is all meant to be inside a "def checkout()" function (so i can later right a main program including the search function I wrote and one that allows you to 'return' the books) but if I try to put it inside it all I get are indent errors, and whenever I tried to use breaks in order to stop the program from repeating "Sorry, either the book ID was not found or the book is unavailable" for every book or every other book the whole thing would die. At this point I'm just looking for basic functionality even if it doesn't work perfectly so the main priority is to get it actually running.
while True:
txt = open("book_list.txt", "r+")
try:
user_id = int((raw_input("Please enter your ID: ")))
if len(str(user_id)) != 4:
print "Sorry, that was an invalid ID. Please try again."
continue
break
except:
print "Sorry, that was an invalid ID. Please try again."
book_id = (raw_input("Please enter the book ID no. you would like to take out: "))
for line in txt:
if book_id == line[0] and line[-1] == " ":
txt.write(line.replace(line,user_id))
print "You have successfully taken out the book."
else:
print "Sorry, either the book ID was not found or the book is unavailable."
txt.close()
The text file in question is just:
1 Book_1 Author_1 1234
2 Book_1 Author_1
3 Book_2 Author_2
4 Book_3 Author_3 2000
5 Book_4 Author_3
The book ID is the number on the left and the user ID (or space " " which means that the book is available) is the right hand number.
It's probably something really simple that I'm missing and have done to make it not work because I'm a beginner but I appreciate any input, cheers.
First of all remove open statement from while loop , it keeps opening file unnecessarily.
while True:
try:
user_id = int((raw_input("Please enter your ID: ")))
if len(str(user_id)) != 4:
print "Sorry, that was an invalid ID. Please try again."
continue
break
except:
print "Sorry, that was an invalid ID. Please try again."
book_id = (raw_input("Please enter the book ID no. you would like to take out: "))
Secondly use with statement while dealing with files so you dont have to keep track of closing it.
Also opening your file in "r+" mode is going to complicate the issue as data is going to be appended in the end, you may utilize seek and tell but it is not going to make things any easier also you may overwrite your data, so i suggest you to use a temporary file
out_txt = open("temp.txt","w")
found = False
with open("book_list.txt", "r") as txt:
for line in txt:
if book_id == line[0] and line[-1] == " ": # are you sure that every line that does not have an user_id associated to it is going to have a " "(space) at the end of it, if not think of some other condition to do this
line = line.strip() + " " + str(user_id) + "\n"
print "You have successfully taken out the book."
found = True
out_txt.write(line)
out_txt.close()
if found:
import os
os.remove("book_list.txt")
os.rename(out_txt.name, "book_list.txt")
else:
print "Sorry, either the book ID was not found or the book is unavailable."