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

[Fabian Grünbichler]

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}));