Pluralize filter shouldn't pluralize decimal/float values between 1 and 2

[Ryan Fugger]

The pluralize filter's support for floating point/decimal numbers is buggy. Its check for plurality is:

if int(value) != 1

which unfortunately catches floats 1.0 < x < 2.0 that shouldn't be pluralized in English.

Example:

pound{{ weight|pluralize:"s" }}

When weight is 1.3, this gives "1.3 pound", which is incorrect. "1.3 pounds" is the expected result.

The filter should probably also pluralize 1.0 when it is given as a floating point/decimal number, because native speakers will generally pluralize all decimal numbers. ("One-point-oh hours," not "One-point-oh hour".)

Reference:
​http://www.englishforums.com/English/1119PluralOrSingular/wdvmb/post.htm#684376

[Adam Gomaa]

Patch to fix w/ tests attached.

I agree that it would make sense for 1.0 to also be pluralized, however, I didnt make that change in this patch for three reasons:

• It turns this from a one-line change to something significantly more complex, since we have to treat the strings "1" and "1.0" differently
• It could break people's existing code, if they don't realize they're passing in a float
• Where "1.0 pounds" is desired instead of "1 pound"/"1.1 pounds", pluralize wouldn't be needed in the first place, the template would just be:

{{ weight|floatformat:1 }} pounds

With this patch, for "1 pound" & "1.1 pounds", we can do:

{{ weight|floatformat }} pound{{ weight|pluralize }}

This is consistent with the decision made in #12380.

[Aymeric Augustin]

The docs say that pluralize "returns a plural suffix if the value is not 1".

It looks like int(value) is only intended to convert a string to an int and pluralize wasn't designed to deal with float values.

An alternative fix could be to change the check to if str(value) != "1". Thus 1.0 will be pluralized and it's still a one-liner.

[Aymeric Augustin]

Re-reading the original report and the first comment closely, they actually say that all floats should trigger pluralization, even 1.0.

This makes the pluralize filter unnecessary when used with floats.

[Daniel Watkins]

This does cause a problem with DecimalField. If I do:

MyModel.objects.create(decimal_field=Decimal('1.0'))

then this comes out of the ORM as:

Decimal('1')

which the templating system will display as "1" (rather than "1.0" or another float-y representation). (This is also the case if I pass in the float 1.0.)

Therefore, I can't "hard-code" the pluralised noun, because I might end up with "1 widgets" rather than "1 widget". If I use |pluralize, then I end up with "1 widget" but also "1.2 widget".

I'm happy to be corrected, but it seems to me that this is a valid bug.

[Aymeric Augustin]

I don't understand the last comment, Decimal('1.0') is handled by the |pluralize filter as a singular value and is displayed as 1 in the template. So everything is correct. I'm going to add a test.

[Aymeric Augustin <aymeric.augustin@…>]

In 1a01e24331194a8580d9f16b02e02f8403680942:

Tested pluralization of decimals.

Refs #16723.