JSON decode failed - json

Question

Following is the code snippet where I am observing error: "malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "(end of string)") at"
Error observed is at the decode_json line. Can someone point out what is the error?
my $serverurl = "http://mycompany.net/rest/api/2/";
my $username = 'my.email#domain.com';
my $password = "mypassword\#2019";
my $i ;
my $test;
my $headers = {Accept => 'application/json', Authorization => 'Basic ' .encode_base64($username . ':' . $password)};
my $client = REST::Client->new();
my $idartinstance;
my $idartinstance1;
if (!$idartinstance)
{
print " Trying to Connect to URL using REST client interface \n\n";
$idartinstance1 = $client->GET($serverurl."serverinfo",$headers);
$idartinstance = decode_json($idartinstance1->responseContent());
}
When I print $idartinstance, I get this:
REST::Client=HASH(0x8682024)->responseContent()
Does this mean, it is not able to find REST client?
[EDIT] I have modified the script as below and no difference in the errors.
my $serverurl = "https://mycompany.net/rest/api/3/";
my $username = 'my.email#domain.com';
my $password = 'pf9fCdkGXmi4pMHiwIh74A0D';
my $headers = {Accept => 'application/json', Authorization => 'Basic ' . encode_base64($username . ':' . $password)};
my $client = REST::Client->new();
if (!$idartinstance)
{
print " Trying to Connect to JIRA using REST client interface \n\n";
$client->GET($serverurl."serverInfo", $headers);
print $client->responseContent();
$idartinstance = decode_json($client->responseContent());
}
Now I have used encoded password. Error is same: malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "(end of string)"). Tried accessing "https://mycompany.net/rest/api/3/serverInfo" via web browser and able to get the details.

Answer 1

Once you get a response, you have to check that its what you want.
if( $client->responseCode() eq '200' ){
print "Success\n";
}
You may also want to check that the content-type is what you expect. If it's supposed to be JSON, check that it is:
if( $client->responseHeader('Content-Type') =~ m|\Aapplication/json\b| ) {
print "Got JSON\n";
}
Once you've established that you have what you wanted, pass the message body off to the JSON decoder.
my $data = decode_json($client->responseContent());
You might also try to catch errors where you should have valid JSON but don't. The block eval can handle that (and see the many sources of the proper employment of eval for its best use):
my $data = eval { decode_json(...) };
I find that I tend to get the wrong content in two situations:
the wrong endpoint, from which a 404 handler returns HTML
a captive portal, which also returns HTML

Answer 2

I think you're misreading the documentation for the module. From the synopsis there, the example that most closely resembles yours is the first one:
my $client = REST::Client->new();
$client->GET('http://example.com/dir/file.xml');
print $client->responseContent();
Notice, in particular, that this example does nothing with the return value from GET(). In your example you do the equivalent of this:
my $client = REST::Client->new();
my $resp = $client->GET('http://example.com/dir/file.xml');
print $resp->responseContent();
As it happens, although there is no documented return value from GET() [Update: I was wrong here - see the first comment - but the return value is really only intended for chaining method calls], it actually returns the object that it was passed, so your approach should work. But it's generally a bad idea to not follow the documentation.
So what is actually going wrong? Well, I'm not sure. As I said, your approach should (accidentally) work. But the error message you're getting tells us that what you're passing to decode_json() is a REST::Client object, not a string containing JSON. I don't think that's how your code should work. Perhaps the code you've shown us isn't actually the code you're running.
The best approach to debug this is to follow the advice from Quentin in the first comment on your question - print the value that you're trying to pass to decode_json() before passing it to the function. In fact, that's good general programming advice - originally write out your code step by step, and only combine steps once you know that the individual steps are working correctly.
Using your variable names, I think your code should look like this:
my $client = REST::Client->new();
# ...other code...
$client->GET($serverurl."serverinfo", $headers);
print $client->responseContent();
# And, only once you've established that
# $client->responseContent() returns what
# you expect, you can add this:
$idartinstance = decode_json($client->responseContent());
If the print() statement doesn't show you JSON, then update your question to add whatever is printed and we'll take a further look.