It's difficult to give advice because the code you need to write will be highly dependent on the data structure returned by decode_json, which is highly dependent on the structure of your JSON string.
If you are going to be extracting data from complex JSON strings, then it may be helpful to use a module that helps you extract the data (without having to worry about the perl data structure). One such module is JSON::Path. It lets your write a JSONPath string to extract the data. This way you can write a JSONPath string that will extract only the portion of data that you are interested in and it will reduce the amount of perl code you need to write. I have converted your script of use JSON::Path to give you an example to work from.
#!/usr/bin/env perl
use strict;
use warnings;
use JSON::Path;
my $json = '{
"_embded" : {
"stes" : [ {
"SampleSize" : "3,117 ",
"ge" : false,
"gx" : false,
"Count" : 1922309,
"qualifier" : null,
"imputed" : true,
"pooled" : false,
"Comment" : null,
"Id" : "G00854",
"full" : false,
"Requested" : false,
"forms" : [ {
"manufacturer" : "ymetrix"
} ],
"ries" : [ {
"te" : "initial",
"Individuals" : 4390,
"Groups" : [ {
"Group" : "European"
} ],
"Origin" : [ ],
"Recruitment" : [ {
"majorArea" : "Europe",
"region" : "Northern Europe",
"countryName" : "U.K."
} ]
}, {
"te" : "epion",
"Individuals" : 2698,
"Groups" : [ {
"Group" : "European"
} ],
"country" : [ ],
"Recruitment" : [ {
"majorArea" : "Europe",
"region" : "Western Europe",
"countryName" : "Germany"
} ]
}, {
"te" : "ation",
"Individuals" : 1649,
"Groups" : [ {
"Group" : "NR"
} ],
"country" : [ ],
"Recruitment" : [ ]
} ],
"sea" : {
"trt" : "risk"
},
"Technologies" : [ {
"Technology" : "GW"
} ],
"SampleSize" : "2,698 ",
"publicationInfo" : {
"Id" : "247",
"publicationDate" : "2016-12-01",
"publication" : "Psychiat",
"title" : "GTW.",
"author" : {
"fullname" : "Perlis RH",
"orcid" : null
},
"_links" : {
"stes" : {
"href" : " ",
"teated" : true
}
}
},
"_links" : {
"self" : {
"href" : ""
},
"sd" : {
"href" : "",
"templated" : true
},
"asmary" : {
"href" : ""
},
"ets" : {
"href" : ""
},
"ss" : {
"href" : ""
},
"aons" : {
"href" : ""
}
}
} ]
},
"_links" : {
"self" : {
"href" : ""
}
}
}';
my $jpath_stes = JSON::Path->new('$._embded.stes[*]');
# @vals will contain all of the elements of 'stes'
my @vals = $jpath_stes->values($json);
my $jpath_ge = JSON::Path->new('$._embded.stes[0].SampleSize');
# $val will contain the value found for 'SampleSize' in the first elem
+ent of
# the stes array
my $val = $jpath_ge->value($json);
print "SampleSize: $val\n";
exit;
If you choose to use this module, I recommend you carefully read the documentation for the
.
