It works now but I get data_out file with wrong order of structure fields - the first field is num_page, not title. Is it possible to make it constant?
| [reply] |
No. Perl hashes have no order, so the sequence in which hash keys are serialized is more or less random.
Update: Note that Javascript does not define an order over the properties of objects either, so there is very little guarantee that a JSON document will have the keys in a specific order. It seems that ECMAscript 6 standardizes somewhat on "insertion order".
The JSON definition declares that
An object is an unordered set of name/value pairs.
So, for hashes, JSON does not specify an order of the keys.
| [reply] |
If you wish it to be ordered in your output (more for human consumption), look at the JSON Documentation at the canonical option.
Update: fixed link (Your Mother)
| [reply]
[d/l] |
++Corion, and so if you want ordered pairs (same rules for json as Perl), the most obvious treatment is to replace that hash with an array of little hashes, e.g.:
use strict;
use warnings;
binmode STDOUT, ":utf8";
use utf8;
use JSON;
my $json ={
'book' => [
{'title' => 'smth'},
{'num_page' => 234}
]
};
open my $fh, ">", "data_out.json";
print $fh encode_json($json);
close $fh;
Alternatively, you could sort the hash keys on the receiving end in Javascript into a particular order (put the key names in another hash with the sort positions as values for use in a sort function in Javascript) but that would be outside the scope of the monastery.
| [reply]
[d/l] |
Hi! I'm getting this error while using binmode STDOUT, ":utf8". Please help! :)
Failed to require abc.pm because Can't locate object method "BINMODE" via package "OutputTee" at /home/perl.abc.pm line 33.
| [reply] |