My Python dicitionary storing only the last key value pair.

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i have a function to check for some data in few tables and create a dictionary using its two specific values.i am only able to add the current value and the previous value is deleted.

What I have tried:

def update_dict(detail):
    printerdict={}
    toner_printer_id=Toners.objects.get(id=detail.toner_model_id)
    printdescription=Items.objects.get(id=toner_printer_id.toner_printer.id)
    print_description=printdescription.description
    print(print_description)
    tonerid=update_items.detailId
    ptdescription=print_description
    # for tonerid,ptdescription in printerdict:
    if tonerid not in printerdict:
            printerdict[tonerid]=ptdescription
    for k,v in printerdict.items():
        print(k,v)

Posted 26-Aug-22 7:12am

Muneer Mohd

Updated 27-Aug-22 8:57am

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2 solutions

Solution 2

printerdict={}
def update_dict(detail):
    printerdict={}
    toner_printer_id=Toners.objects.get(id=detail.toner_model_id)
    printdescription=Items.objects.get(id=toner_printer_id.toner_printer.id)
    print_description=printdescription.description
    print(print_description)
    tonerid=update_items.detailId
    ptdescription=print_description
    # for tonerid,ptdescription in printerdict:
    if tonerid not in printerdict:
            printerdict[tonerid]=ptdescription
    for k,v in printerdict.items():
        print(k,v)

Posted 27-Aug-22 8:57am

Muneer Mohd

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Richard MacCutchan · Accepted Answer · 2022-08-26T22:28:00

The problem is that every time you call update_dict it creates a new printerdict variable. So it only ever adds one item to the dictionary and then terminates the function. You need to create the dictionary as a global, so it exists beyond the lifetime of the function. So change it to:

Python

printerdict={}
def update_dict(detail):
    # rest of the code here

See 9.2. Python Scopes and Namespaces at 9. Classes — Python 3.10.6 documentation[^]