[Tutor] Pickle Class Instances
andreas.perstinger at gmx.net
Tue Nov 1 07:53:04 CET 2011
On 2011-11-01 06:31, Rinu Boney wrote:
> def add_book(b):
> The Display After Unpickling Shows only the last Class Instance.
> How To Display All The Data In The File ?
You haven't shown us the complete program (how to you call "add_book"
and "display_books"?) but I guess that you call "add_book" with one
instance (if not, you can ignore the rest). In that case there is no
more data in the file.
In your "add_book" function you open the file "books.at" and just save
one instance. The next time you call the function with another instance
you overwrite the former, because opening the same file with the
parameter "w" (or in your case "wb") deletes any already existing content.
What you probably want is to put all the instances into a list and save
this list. When you later read the file, you'll get the list back and
you can iterate over it for displaying.
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