[pve-devel] [PATCH v2 common] cli-formatter: avoid warning when trying to sort on undefined key

[Fabian Grünbichler]

On November 28, 2019 10:12 am, Thomas Lamprecht wrote:
> On 11/28/19 10:08 AM, Fabian Grünbichler wrote:
>> On November 27, 2019 4:59 pm, Thomas Lamprecht wrote:
>>> On 11/26/19 1:10 PM, Christian Ebner wrote:
>>>> Example:
>>>>     pvesh get /nodes/{node}/qemu/{vmid}/rrddata --timeframe day
>>>>
>>>> If the sorting key is not defined in the dataset, e.g. when a VM was not running
>>>> for some time within the given timeframe, this resulted in several ugly warnings.
>>>>
>>>> Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
>>>> ---
>>>>
>>>> v2: Oops, v1 is nonsense and breaks sorting.
>>>>
>>>>  src/PVE/CLIFormatter.pm | 6 ++++--
>>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/src/PVE/CLIFormatter.pm b/src/PVE/CLIFormatter.pm
>>>> index 0e9cbe6..21fa2df 100644
>>>> --- a/src/PVE/CLIFormatter.pm
>>>> +++ b/src/PVE/CLIFormatter.pm
>>>> @@ -175,9 +175,11 @@ sub print_text_table {
>>>>      if (defined($sort_key) && $sort_key ne 0) {
>>>>  	my $type = $returnprops->{$sort_key}->{type} // 'string';
>>>>  	if ($type eq 'integer' || $type eq 'number') {
>>>> -	    @$data = sort { $a->{$sort_key} <=> $b->{$sort_key} } @$data;
>>>> +	    @$data = sort { $a->{$sort_key} <=> $b->{$sort_key}
>>>> +		if defined $a->{$sort_key} && defined $b->{$sort_key} } @$data;
>>>>  	} else {
>>>> -	    @$data = sort { $a->{$sort_key} cmp $b->{$sort_key} } @$data;
>>>> +	    @$data = sort { $a->{$sort_key} cmp $b->{$sort_key}
>>>> +		if defined $a->{$sort_key} && defined $b->{$sort_key} } @$data;
>>>
>>>
>>> a post-if in a sort condition feels a bit awkward and does not
>>> clearly tells a reader what the behavior for undefined cases is, IMO
>>>
>>> Maybe use a ternary operation here:
>>> sort {
>>>     defined $a->{$sort_key} && defined $b->{$sort_key}
>>>         ? $a->{$sort_key} cmp $b->{$sort_key}
>>>         : 1
>>> }
>>>
>>>
>>> or as alternative a sorter method:
>>>
>>> my $hashsort = sub {
>>>     my ($a, $b, $key) = @_;
>>>     return 1 if !(defined $a->{$key} && defined $b->{$key});
>>>     return $a->{$key} cmp $b->{$key};
>>> }
>>>
>>> and use that?
>>>
>>> Or even:
>>>
>>> return 1 if defined $a->{$key} && !defined $b->{$key});
>>> return -1 if !defined $a->{$key} && defined $b->{$key};
>>> return 0 if defined $a->{$key} && defined $b->{$key};
>>>
>>> ?? that stuff confuses me after a longer day, sorry ^^
>> 
>> complete would actually be, with the (hopefully) most likely  case up 
>> front, and the assumption that undef is less than anything defined ;)
>> could of course also be written as if / elsif / elsif / else, to make it 
>> more obvious that all cases are handled.
>> 
>> return $a->{$key} cmp $b->{key} if defined($a->{key}) && defined($b->{key});
>> return 1 if defined($a->{$key}) && !defined($b->{$key});
>> return -1 if !defined($a->{$key}) && defined($b->{$key});
>> return 0 if !(defined($a->{$key}) && defined($b->{$key}));
>> 
> 
> That's the exact same I proposed?? or do I miss something?

your first variants only cover two cases (both defined, or both undef), 
your second variant only covers three cases and does no comparison when 
both are defined ;) there are actually four cases (think of definedness 
as bool).