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Re: Getting error while decoding JSON object via POST method
by tobyink (Canon) on Feb 06, 2013 at 06:39 UTC
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my $jsonText = $q->param('inputdata');
my $outputDataRef = $json->decode($inputData);
If you'd used strict Perl would have told you about the undeclared variable $inputData.
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
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Sorry for not providing the complete code.
updated the code just now. problem is not with variable definition, please check the error:
malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "(end of string)"
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>perl -MJSON -e "print JSON->new->decode('')"
malformed JSON string, neither array, object, number, string or atom,
+at character offset 0 (before "(end of string)") at -e line 1.
I think you are trying to pass the data around in a very bad manner:
<c>
"/projectname/restfulapi?inputdata=$jsonData";
<c>
If you send POST data, please read HTTP::Request on how to send POST data. If you want to send the data in an URI, please encode it properly using URI::Encode. | [reply]
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This error message occurs when you pass the empty string or an undefined variable to be decoded by JSON, JSON::PP or JSON::XS.
So I'd suggest that even with the updated code, the problem is related to the initialization of $jsonText - it appears to be undef.
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
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Re: Getting error while decoding JSON object via POST method
by tobyink (Canon) on Feb 06, 2013 at 09:48 UTC
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Here is an example of a CGI script that accepts JSON via HTTP POST, reads two numbers "a" and "b" from the input, and adds them together returning "c", plus an example client that uses the script...
#!/usr/bin/env perl
use strict;
use warnings;
use CGI ();
use JSON ();
my $q = CGI->new;
my $json = JSON->new->utf8;
my $input = $json->decode( $q->param('POSTDATA') );
my $a = $input->{a};
my $b = $input->{b};
my $c = $a + $b;
print $q->header("application/json");
print $json->encode({ c => $c });
#!/usr/bin/env perl
use strict;
use warnings;
use JSON ();
use LWP::UserAgent ();
use HTTP::Request::Common qw( POST );
my $data = { a => 40, b => 2 };
my $json = JSON->new->utf8;
my $ua = LWP::UserAgent->new;
my $req = POST(
"http://buzzword.org.uk/2013/json-addition.cgi",
Content_Type => 'application/json',
Content => $json->encode($data),
);
my $result = $json->decode( $ua->request($req)->decoded_content );
print $result->{c}, "\n";
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
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thanks for response, still getting same error. i tried code :
cleint :
use strict;
use warnings;
use JSON ();
use LWP::UserAgent ();
use HTTP::Request::Common qw( POST );
use Data::Dumper;
my $data = { a => 40, b => 2 };
my $json = JSON->new->utf8->allow_nonref;
my $ua = LWP::UserAgent->new;
my $req = POST(
"$my_url",
Content_Type => 'application/json',
Content => $json->encode($data),
);
my $response = $ua->request($req);
if ($response->is_success) {
#print Dumper($response->content());
my $perlData = $json->decode($response->content());
print Dumper($perlData);
}
else{
print " inside falied block\n";
}
server side:
#use cgi.pm to get json as input
my $q = CGI->new;
my $json = JSON->new->utf8;
my $input = $json->decode( $q->param('POSTDATA') );
#my $input = $q->param('POSTDATA');
my $a = $input->{'a'};
my $b = $input->{'b'};
my $c = $a + $b;
print $q->header("application/json");
#print Dumper($input);
print $json->encode({ c => $c });
output of run :
./test_client.pl
$VAR1 = {
'error_msg' => 'Failed during execution: malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "(end of string)")
',
'status_code' => 500
};
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And the reason you don't DUMP the data is because?
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I'm getting this exact same error when trying to access the body of an application/json POST when the request is HTTP 1.1. If it's an HTTP 1.0 request, all is fine. HTTP 1.1 requests don't set the "Content-Length" header and use "Transfer-Encoding" with a value of "chunked". Does anyone know the proper way to grab the JSON payload of a POST request that will work with both HTTP 1.0 and HTTP 1.1?
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Re: Getting error while decoding JSON object via POST method
by Mr. Muskrat (Canon) on Feb 07, 2013 at 20:00 UTC
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my $perlData = $json->decode($response->content());
You don't want the raw content returned by $response->content(). You want the decoded content as returned by $response->decoded_content(). tobyink had it correct in his reply but he didn't explicitly call it out and you didn't pick up on it.
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I know that this is an old thread, but I'm having exactly this problem and the answer presented isn't entirely satisfactory. What I mean is that the problem presented used the CGI module on the server side, but the solution presented (using $request->decoded_content instead of $request->content) applies to the client script, which uses LWP, but not to the server script. I don't see anything in the CGI module that will do the required decoding. In my case, I'm using Apache and an Apache::Request object, which also does not (from what I can find on the web) chunked data. I have no control over the format of the data arriving at my server. Most of the time my script works, presumably because it's usually not chunked.
I am using Fiddler to debug my script. When I first inspect the response, the POST body appears to have stray characters before and after the actual JSON code. However, Fiddler tells me that I need to decode it, which I do by simply clicking a button, after which the JSON appears correct. This leads me to believe that I'm having exactly the problem described in this thread. If I had an HTTP::Request object, I would just call $req->decoded_content() but the only way that I know to get one is using LWP, which doesn't make sense on the server side.
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So, can you show us the code you are using, together with "good" and "bad" input data? Ideally, the code would be about 20 lines.
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use HTML::Entities qw/decode_entities/;
my $ok=decode_entities($orig);
Im not sure this would work on "chunks", $orig has to be the entire string to decode at once for with chunks an entity could be split across them.
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