如何捕获“解码JSON失败"消息? Perl中出现错误消息? [英] How can I catch a "failed to decode JSON" error message in Perl?

问题描述

所以我正在尝试 load 测试返回JSON值的REST API.

So I am trying to load test a REST API which returns a JSON value.

为此，我正在创建perl脚本的多个实例.

To do that I am creating multiple instances of the perl script.

Perl脚本基本上会调用该URL，然后尝试进入decode_json.显然，当产生大量负载时，它就会失败.

The Perl script basically calls that URL, and tries to decode_json. Obviously when substantial load is generated, it fails.

现在我面临的问题是-命令提示符上显示一个错误，但未在文件中写入该错误消息.

Now the problem I face is- An error is displayed on command prompt but does not write that error message in a file.

错误消息是

malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "Can't connect to 209...") at json_load_test.pl line 39.

第39行下面的所有三种尝试均指:

In all the three attempts below line 39 refers to:

decode_json($actual_response);

我只是在命令提示符下以以下方式运行脚本:

I am simply running the script on the command prompt as:

perl json_load_test.pl >> logs/output.txt 

我希望在"output.txt"中写入错误消息

我的三个失败尝试如下.

my $ua = LWP::UserAgent->new;
$ua->timeout(3);    
$ua->env_proxy;        
my $response = $ua->get("http://$j_env/jobs/all.json?status=active");
my $actual_response=$response->decoded_content;
decode_json($actual_response);
if ($? == -1)
{print "\n Failed to execute: $!\n"; }

尝试2:

my $ua = LWP::UserAgent->new;
$ua->timeout(3);    
$ua->env_proxy;        
my $response = $ua->get("http://$j_env/jobs/all.json?status=active");
my $actual_response=$response->decoded_content;
my $perl_scalar= decode_json($actual_response);
if ($perl_scalar)
{ok(1,"For process $u2 inside counter $counter ");}
else
{ok(0,"FAILED!!! process $u2 inside counter $counter");}

尝试3:

my $ua = LWP::UserAgent->new;
$ua->timeout(3);    
$ua->env_proxy;        
my $response = $ua->get("http://$j_env/jobs/all.json?status=active");
my $actual_response=$response->decoded_content;
decode_json($actual_response) or die "FAILED!!!!";

推荐答案

您的错误消息似乎来自stderr，而不是stdout.因此，

It looks like your error message is coming from stderr, not stdout. Thus,

perl json_load_test.pl >> logs/output.txt 2>> logs/errors.txt

或者类似的东西.如果您想将两个文件都放在一个文件中:

Or something to that effect. If you want both in one file:

perl json_load_test.pl 2>&1 >> logs/output.txt

如果出于某种原因您想在perl中捕获错误并将其发送到stdout，则可以:

If for some reason you wanted to trap the error in the perl and send it to stdout, you could:

eval {
  decode_json($actual_response);
  1;
} or do {
  my $e = $@;
  print "$e\n";
};

正如daxim在编辑说明中指出的，Try :: Tiny可能更简单:

As daxim points out in the edit notes, Try::Tiny may be simpler:

use Try::Tiny;
try {
  decode_json($actual_response);
} catch {
  print "$_\n";
};

这篇关于如何捕获“解码JSON失败"消息? Perl中出现错误消息?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！