json - 将 Perl 字符串转换为 json 数组

Question

我正在尝试编写一个将在 Centos 6 主机上运行的 Perl 脚本。该脚本将运行一个 shell 命令来查询我们的 AWS 接口(interface)，如下所示:

my $json = `aws ec2 describe-instances`;

此查询将返回一个 JSON 对象，但我相信我的问题是它实际上作为字符串存储在 $output 中，而不是实际存储在 JSON 对象中。

我正在尝试以下代码:

# Get each instance
my $json = `aws ec2 describe-instances`;

# Decode AWS json result
my $decoded = decode_json $json;

# Find reference type
print "Reference type: " . ref $decoded,"\n";

# Loop through each EC2 instance
print $decoded -> {Reservations} . "\n";

当我执行此代码时，我收到以下消息:

Reference type: HASH
ARRAY(0xa774b0)

有人可以帮我解决这个问题吗？我已经在谷歌上搜索并搞乱了这一整天了:(

下面是存储在 $output 中的字符串示例，尽管在实际输出中会有多个实例:

{
    "Reservations": [
        {
            "OwnerId": "82XXXXXXX043",
            "ReservationId": "r-0XXXXXXXXXXX",
            "Groups": [],
            "Instances": [
                {
                    "Monitoring": {
                        "State": "XXXXX"
                    },
                    "PublicDnsName": "XXX",
                    "RootDeviceType": "XXXXXXX",
                    "State": {
                        "Code": XXX,
                        "Name": "stopped"
                    },
                    "EbsOptimized": XXXX,
                    "LaunchTime": "XXXXXXXXXX",
                    "PrivateIpAddress": "XXXXXXXXXX",
                    "ProductCodes": [],
                    "VpcId": "XXXXXXXXXX",
                    "StateTransitionReason": "UXXXXXXXXXX",
                    "InstanceId": "XXXXXXXXXX",
                    "ImageId": "XXXXXXXXXX",
                    "PrivateDnsName": "XXXXXXXXXX",
                    "KeyName": "XXXXXXXXXX",
                    "SecurityGroups": [
                        {
                            "GroupName": "XXXXXXXXXX",
                            "GroupId": "XXXXXXXXXX"
                        },
                        {
                            "GroupName": "XXXXXXXXXX",
                            "GroupId": "XXXXXXXXXX"
                        },
                        {
                            "GroupName": "XXXXXXXXXX",
                            "GroupId": "XXXXXXXXXX"
                        }
                    ],
                    "ClientToken": "XXXXXXXXXX",
                    "SubnetId": "XXXXXXXXXX",
                    "InstanceType": "XXXXXXXXXX",
                    "NetworkInterfaces": [
                        {
                            "Status": "XXXXXXXXXX",
                            "MacAddress": "XXXXXXXXXX",
                            "SourceDestCheck": XXXXXXXXXX,
                            "VpcId": "XXXXXXXXXX",
                            "Description": "XXXXXXXXXX",
                            "NetworkInterfaceId": "XXXXXXXXXX",
                            "PrivateIpAddresses": [
                                {
                                    "Primary": XXXXXXXXXX,
                                    "PrivateIpAddress": "XXXXXXXXXX"
                                }
                            ],
                            "Ipv6Addresses": [],
                            "Attachment": {
                                "Status": "XXXXXXXXXX",
                                "DeviceIndex": 01234,
                                "DeleteOnTermination": XXXXXXXXXX,
                                "AttachmentId": "XXXXXXXXXX",
                                "AttachTime": "XXXXXXXXXX"
                            },
                            "Groups": [
                                {
                                    "GroupName": "XXXXXXXXXX",
                                    "GroupId": "XXXXXXXXXX"
                                },
                                {
                                    "GroupName": "XXXXXXXXXX",
                                    "GroupId": "XXXXXXXXXX"
                                },
                                {
                                    "GroupName": "XXXXXXXXXX",
                                    "GroupId": "XXXXXXXXXX"
                                }
                            ],
                            "SubnetId": "XXXXXXXXXX",
                            "OwnerId": "XXXXXXXXXX",
                            "PrivateIpAddress": "XXXXXXXXXX"
                        }
                    ],
                    "SourceDestCheck": XXXXXXXXXX,
                    "Placement": {
                        "Tenancy": "XXXXXXXXXX",
                        "GroupName": "XXXXXXXXXX",
                        "AvailabilityZone": "XXXXXXXXXX"
                    },
                    "Hypervisor": "XXXXXXXXXX",
                    "BlockDeviceMappings": [
                        {
                            "DeviceName": "XXXXXXXXXX",
                            "Ebs": {
                                "Status": "XXXXXXXXXX",
                                "DeleteOnTermination": XXXXXXXXXX,
                                "VolumeId": "XXXXXXXXXX",
                                "AttachTime": "XXXXXXXXXX"
                            }
                        }
                    ],
                    "Architecture": "XXXXXXXXXX",
                    "StateReason": {
                        "Message": "XXXXXXXXXX",
                        "Code": "XXXXXXXXXX"
                    },
                    "IamInstanceProfile": {
                        "Id": "XXXXXXXXXX",
                        "Arn": "XXXXXXXXXX"
                    },
                    "RootDeviceName": "XXXXXXXXXX",
                    "VirtualizationType": "XXXXXXXXXX",
                    "Tags": [
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        },
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        },
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        },
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        },
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        },
                        {
                            "Value": "XXXXXXXXXX",
                            "Key": "XXXXXXXXXX"
                        }
                    ],
                    "AmiLaunchIndex": XXXXXXXXXX
                }
            ]
        }
    ]
}

Answer 1

您的 JSON 以 { 开头，因此错误是完全正确的。您没有数组引用，而是哈希引用。

尝试 print ref $decoded,"\n" 它会告诉您您拥有的引用类型。

尝试 $decoded -> {Reservations} 或使用 Data::Dumper 打印整个内容:

use Data::Dumper;
print Dumper $decoded;