KeyError when adding item to cart

[sect2k]

After an item is added to cart, KeyError is raised on subsequent pages. This is because keys in cart_representation dictionary are strings and if product.pk is a number, the key is not found in the dict.

The fix is simple, change

 item = cart_representation[product.pk]

to

 item = cart_representation[str(product.pk)]

Pushed a fix.

[lazybird]

I'm not sure why we need to cast product.pk to a string. It seems to me that the key in cart_representation is already a numeric.

In fact I actually get a key error when I use item = cart_representation[str(product.pk)].

For now, I will revert the change - since it break tests and it's committed on master.

sect2k, I'm curious to understand how you ran into this issue and how come you had to cast the key into a string.

Thanks.

[sect2k]

Not sure what exactly causes this issue, but the behavior is strange, as sometimes the key in cart_representation is a string and other times it's a number.

In my case, I started getting the error I described in OP, then it worked fine for a while after I cast the key into string and then a few days a go I started getting KeyError again, this time because the key was again a number.

My solution was to cast also explicitly cast the key to string when creating cart_representation, this way the key is always a string, and since string is more versatile then number (some products might actually have a string for a primary key) I believe this is the best fix for the issue.

Do to a busy schedule this week, I sort of forgot to push the fix to github.

[lazybird]

I'm wondering if the issue on your side could come from old cached data. I would suggest to keep the key to product.pk without casting it, both when storing the data in the session and also when retrieving it.

[lazybird]

Looking again at the way you've described the inconsistencies, it's possible that the issue on your end is at product model's level... May be something to with pk field.

[sect2k]

I doubt it's cached data and it's not my product pk, it's a standard django auto id, more likely it has to do with JSON decoding/decoding, since session data is JSON serialized.

Might be some inconsistencies in how handles numbers as keys, since in JSON keys are always converted to strings and from a quick experiment in python shell:

d = {123: 'Product'}
j = json.dumps(d)
d2 = json.loads(j)
d2
{u'123':  u'Product'}

Numeric key from d gets converted to unicode string in d2.

I still think the safest option is to cast the key to string explicitly as is seems that JSON serialization does not produce 100% consistent results. Best to be on the safe side.

[lazybird]

I have made a change to use string instead of numeric for the dict key before going thought JSON serialization.

Thanks flagging that issue and being patient and precise on the discussion.