widthratio templatetag fails to handle NaN ratio

[rmoe]

When value or max_value are float('inf') or float('nan') the ratio calculation can raise an exception.

[jwiel86]

Hi, thanks for reporting. Do you mind giving more information on how to reproduce this exception so a newbie could partake? Thanks!

[rmoe]

You just need to call widthratio with float('inf') as both the value and max_value. like so:

{% widthratio 'inf' 'inf' 100 %}

Which will raise this (because ratio is NaN and can't be converted to an integer):

ValueError at /project/
cannot convert float NaN to integer

Request Method:	GET
Django Version:	1.5.4
Exception Type:	ValueError
Exception Value: cannot convert float NaN to integer
Exception Location: /usr/lib/python2.7/dist-packages/django/template/defaulttags.py in render, line 467

For some additional context, this was encountered in the Horizon component of the OpenStack project. ​https://github.com/openstack/horizon/blob/master/horizon/templates/horizon/common/_limit_summary.html#L6

When disabling quotas in the Nova component (the data it's trying to build the pie charts for) all quota values are set to -1 which equates to an infinite quota. So in the case where quotas are disabled usage.limits.totalInstancesUsed and usage.limits.maxTotalInstances are both float('inf'). This breaks the project overview page because of the exception raised from the widthratio templatetag.

[Aymeric Augustin <aymeric.augustin@…>]

In 07ae47f7f8b5d5f80238ea3018163cad12917852:

Fixed #21959 -- Handled Inf/NaN in widthratio tag.

Thanks rmoe for the report and the patch.