iterating through json decode

Bobert1234 has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I'm trying to iterate through a json decoded string (using JSON::PP's decode) in order to replace individual elements with corresponding perl objects (e.g. strings starting with ISODate with Time::Moment). i keep running into issues due to the structure of the json_decoded object. i'm new to per and traversing the structure to get to the parts i want to replace is a nightmare of hash/array referencing/dereferencing. here's what i have. could someone please point me to where i'm going wrong?

my $qstr = 'MONGOQUERY[
        {
            $match: {
                $or : [{"prefix" : "27450500"}, {"creationDate": ISODa
+te("2017-06-18T12:52:16.000")}]
            }
        },
        {
            $project: {
                _id:0,
                prefix:1
            }
        },
    ]';


$qstr=~s/MONGOQUERY//gs;
$qstr=~s/ISODate\("([^)]*?)\)/"ISODate$1/gs;


#Timestamp,ISODate, NumberDecimal,NumberLong,NumberInt,Symbol
my $qarrayref = JSON::PP->new->allow_nonref->relaxed->allow_barekey->l
+oose->decode($qstr);

my $rlimit=50;
repl_mongo(\@{$qarrayref},$rlimit);



sub repl_mongo{
 if($_[1]>0){
  open(my $fh, '>>', '/tmp/mongosample.txt');
    if(ref($_[0]) eq 'ARRAY'){
        foreach my $item(@{$_[0]}){
            repl_mongo($item,$_[1]-1 );
        }
    }elsif(ref($_[0]) eq 'HASH'){
        foreach my $item (keys %{$_[0]}){
            repl_mongo($key,$_[1]-1 );
        }
    }else{
            if(index("ISODate", $_[0]) >= 0){
                $_[0] =~s/ISODate//gs;
            #    $_[0] =Time::Moment->from_string($_[0]);
            }
    }
  close $fh;
 }
}

open(my $fh, '>>', '/tmp/mongosample.txt');
    print $fh Dumper($qarrayref);
close $fh;
[download]

Comment on iterating through json decode Download Code

Replies are listed 'Best First'.
Re: iterating through json decode by poj (Abbot) on Feb 08, 2018 at 14:33 UTC
where i'm going wrong? Add `use strict; use warnings;` `#foreach my $item (keys %{$_[0]}){ # repl_mongo($key,$_[1]-1 ); foreach my $key (keys %{$_[0]}){ repl_mongo($_[0]->{$key},$_[1]-1 ); }` [download] Also see index `#if (index("ISODate",$_[0]) >= 0){ if (index($_[0],"ISODate") >= 0){` [download] Note to use Time::Moment`->from_string($string);` The string must consist of a complete date representation and time of day followed by a zone designator. poj	[reply] [d/l] [select]
Re^2: iterating through json decode by Bobert1234 (Novice) on Feb 08, 2018 at 17:43 UTC
Thank you very much poj ! that was super helpful.	[reply]
Re: iterating through json decode by Eily (Monsignor) on Feb 08, 2018 at 14:38 UTC
\@{$ref} is the same as $ref, because @{$ref} accesses the array that $ref points to, and adding a \ gets the same reference. While accessing @_ inside a function does work, I think you should put your arguments in variable (which should be done when @_ isn't a list of similar things but each argument has its own meaning. So: `sub repl_mongo{ my ($ref, $depth) = @_; return unless $depth; if (ref($ref) eq 'ARRAY') { ... }` [download] (and basically replace every use of $_[0] by $ref, and $_[1] by $depth). `foreach my $item (keys %{$_[0]}){ repl_mongo($key,$_[1]-1 ); }` The loop variable is $item, but you access $key. Do you have strict on? It should have told you about that. And for the date conversion, after you have found that a string starts with ISODate (that's index exactly 0 by the way) you can use substr to extract the date part (which will always be at the same positions, starting from the 8th character).	[reply] [d/l] [select]
Re: iterating through json decode by QM (Parson) on Feb 08, 2018 at 13:54 UTC
Can you not: `use JSON;` [download] -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l]
Re: iterating through json decode by hippo (Bishop) on Feb 08, 2018 at 14:24 UTC
Your `repl_mongo` looks to be a reinvention of Data::Leaf::Walker`->each()`. It might be simpler just to use that instead?	[reply] [d/l] [select]

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