在perl中访问json结构的值 [英] Accessing values of json structure in perl

问题描述

  person => 
我有一个json结构，我正在解码，看起来像这样： {
 city => Chicago，
 id => 123，
 name => Joe Smith，
 pets => {
 cats => [
 {age => 6，name => cat1，type => 连体，体重=> 10千克}，
 {age => 10，name => cat2，type => 连体，体重=> 13公斤}，
]，
狗=> [
 {age => 7，name => dog1，type => 连体，体重=> 20公斤}，
 {age => 5，name => dog2，type => 连体，体重=> 15公斤}，
]，
}，
}，
} 
  

我可以打印 city ， id ， name 做：

  foreach my $ listing（$ decoded-> {person}） 
 {
 my $ city = $ listing-> {city}; 
 my $ name = $ listing-> {name}; 
 name  -  $ city  -  \\\
; 
} 
  

然而，我不确定如何打印 pets->猫或 pets->狗。可以通过以下方式将它们转储：

  my @pets = $ listing-> {pets}  - > {cats }; 
 dump @pets; 
  

但我不确定如何通过假设你的 $ listing 是一个

>人，你必须解引用数组和哈希引用。

 ＃只要我们假设$ listing是一个person 
＃这是在您发布在
＃问题中的foreach内部。
 
＃这将打印所有猫的名字
 foreach my $ cat（@ {$ {cat}}）
 {
＃here $ cat是散列引用
 
说$ cat-> {name}; ＃cat's name 
} 
  

等其他内容。

要符合从结构中可以做到这一点：

  say $ listing-> {pets}  - > {cats}  - > ; [0]  - > {名称}; ＃这将打印'cat1'
  

I have a json structure that I'm decoding that looks like this:

  person => {
    city => "Chicago",
    id => 123,
    name => "Joe Smith",
    pets => {
      cats => [
                { age => 6, name => "cat1", type => "siamese", weight => "10 kilos" },
                { age => 10, name => "cat2", type => "siamese", weight => "13 kilos" },
              ],
      dogs => [
                { age => 7, name => "dog1", type => "siamese", weight => "20 kilos" },
                { age => 5, name => "dog2", type => "siamese", weight => "15 kilos" },
              ],
    },
  },
}

I'm able to print the city, id, name by doing:

foreach my $listing ($decoded->{person})
{ 
    my $city = $listing->{city};
    my $name = $listing->{name};
    name - $city - \n";
}

however, I'm unsure of how to print the pets->cats or pets->dogs. I'm able to do a dump of them by:

my @pets = $listing->{pets}->{cats};
dump @pets;

but I'm not sure how to access them through the hash structure.

解决方案

Assuming your $listing is a person you have to dereference array and hash refs.

# as long as we are assuming $listing is a person
# this goes inside the foreach you posted in your
# question.

# this will print all cats' names
foreach my $cat ( @{ $listing->{pets}->{cats} } )
{
    # here $cat is a hash reference

    say $cat->{name}; # cat's name
}

and so on for other stuff.

To access them from the structure you can do:

say $listing->{pets}->{cats}->[0]->{name}; # this will print 'cat1'

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