从关联数组中获取特定键/值并将它们存储为变量

Question

I need to access the specific key/value of associative array as variables using foreach loop. Getting key/value pairs of all data in the array is not a problem. The problem is with getting a specific key/value . Take the code below for example

<?php

$data = [

    'person1' => 
        [
            'id' => 101,
            'firstName' => 'John',
            'LastName' => 'Smith'

        ],

        'person2' => 
        [
            'id' => 102,
            'firstName' => 'Mary',
            'LastName' => 'Smart'

        ]

];

I can get key/value pairs of all data in the array by the code below:

foreach($data as $firstKey => $firstValue){
    foreach ($firstValue as $secondKey => $secondValue) {
        echo $secondKey. ": ". $secondValue . "<br />";


    }
}

The above code is not exactly what I want. I want to get specific key/value for example, I want to get only the key/value of only the id s.

So I tried something like this:

$specificId = null;
foreach($data as $firstKey => $firstValue){
    foreach ($firstValue as $secondKey => $secondValue) {
        if($secondKey == 'id'){ // using if statement to get key/value pair of person's id
            $specificId = $secondValue; //storing the specific ids as variable
            echo $secondKey . ": ". $specificId . "<br>"; 

        }

    }
}


?>

The above code seems to work but if I also want to get key/value for only firstName , then, I have to write another if statement. I will end up writing so many if statements in the foreach loop. Do you know another way I can write lesser code to get specific key/value pairs?

There are many similar questions like mine but the answer I am looking for is not the objective of any of those questions.

Answer 1

foreach($data as $firstKey => $firstValue) {
       echo array_keys($firstValue, $firstValue['id'])[0].': '.$firstValue['id'].'</br>';
       echo array_keys($firstValue, $firstValue['firstName'])[0].': '.$firstValue['firstName'].'</br>';
}

you can just call the associative array key from the array

This outputs key and values

Answer 2

array_intersect_key should do the job just fine:

$results=[];
foreach($data as $name => $attriubtesPerson)
{
    $results[$name] = array_intersect_key($attributesPerson, ['id' => null, 'firstName' => null]);
}

documentation can be found here

Answer 3

To access specific key values you need to convert the array to Json and access it just like a normal object.

  $data = [ 'person1' => [ 'id' => 101, 'firstName' => 'John', 'LastName' => 'Smith' ], 'person2' => [ 'id' => 102, 'firstName' => 'Mary', 'LastName' => 'Smart' ] ]; $obj = json_decode(json_encode($data)); //to access key=values directly echo $obj->person1->firstname; //to access all firstname only foreach($obj as $o){ echo $o->firstName; }