[patch] Admin interface doesn't handle negative FloatFields

[Eddy Mulyono <eddymulyono@…>]

1. Create a model with

   FloatField(max_digits=8, decimal_places=5, blank=True)
   

2. Use the Admin interface to set the FloatField to '-122.19217'

Expected:
Changes saved.

Bug:

• "Please correct the error below."
• "Please enter a valid decimal number with a whole part of at most 3 digits."
• Entry truncated to '-122.1921', because the HTML input can only take 9 characters (max_digits=8 plus the decimal separator '.')

[James Bennett]

Patch which hopefully fixes this

[James Bennett]

I've attached a patch which changes the IsValidFloat validator to allow an extra character in the float if it starts with a '-'; I'm not 100% certain, but I think this fixes the bug.

[Eddy Mulyono <eddymulyono@…>]

Thanx for the speedy patch. Patch didn't fix the issue, because the HTML <input> still only allows 9 characters, so len(data) POSTed to the view still is 9 chars long, so we never enter the negative-sign-handling code.

if len(data) > (self.max_digits + 1):
    max_allowed_length = data.startswith('-') and (self.max_digits + 2) or ...

We probably need to change the template/widget to have <input size="{{ max_digits + 2 }}">.

[Malcolm Tredinnick]

(In [3788]) Fixed #2760 -- Fixed validation of negative float amounts in forms. Thanks,
James Bennett and Eddy Mulyono.

[Eddy Mulyono <eddymulyono@…>]

bug still present in r3843.

[Eddy Mulyono <eddymulyono@…>]

This works for me.

[Malcolm Tredinnick]

The asymmetry (both in the original patch and in this revised one) bothers me. It looks like we should be using max_allowed_length or self.max_digits consistently.

I'll test this out and commit a patch shortly. Sorry about screwing it up the first time; I didn't check it with my brain switched on.

[Malcolm Tredinnick]

(In [3845]) Fixed #2760 -- Fixed FloatField validator right (take two!) for negative
float amounts.

[Malcolm Tredinnick]

So r3845 seems to allow all legal combinations and rejects -1234, -123.456789, 1234, and 123.456789. I think that's got all the possibilities.

If I have missed a case, can you post the float that fails when you reopen, please.