Use A Variable for an Array of Keys in Multidimentional Arrays in PHP

Question

I have an array, $json_data, I'm trying to parse with a for loop:

This is the array:

array(2) {
    ["data"]=>
    array(4) {
        ["children"]=>
        array(25) {
            [0]=>
            ["first_key"]=>
            array(50) {
                ["second_key"]=> 
                string(9) "My Title"
            }
        }
    }
}

Then in PHP, I set this as $json_data and start pulling data out with a for loop

foreach  ( $json_data['data']['children'] as $key => $value ) {
    echo $title = $value['first_key']['second_key'];
}

Outputs "My Title" as expected.

My question (and if my question is poorly worded, please advise) is, can I set the keys as a variable? I know that I can't set it as a string, but can I pass array of keys to $value like:

$key_array = array('first_key' => array('second_key'));

foreach  ( $json_data['data']['children'] as $key => $value ) {
    echo $title = $value[$key_array];
}

Or something like that?

Making a function to which I could pass the $array to a function that has the $key_array set would also be great, like:

echo get_array_value( $array, $array_keys );

but would love a shove in the right direction.

Do you need to get the data out of the array? What are you trying to do? — user2182349
– user2182349, Commented Oct 16, 2016 at 3:42
Yes, hence the question ;). I would like to set the "path" to the correct key/value pair before the array is created. — Evan Rose
– Evan Rose, Commented Oct 16, 2016 at 3:47

Community · Accepted Answer · 2017-05-23 11:48:32Z

1

First of all, see here:

$key_array = array('first_key' => array('second_key'));

Instead of declaring a multidimensional array of keys, declare a simple array comprising of all the keys whose values you want to fetch from the original array $json_data, like this:

$array_keys = array('second_key', 'another_key');

And second, from your question:

Making a function to which I could pass the $array to a function that has the $key_array set would also be great, like:
echo get_array_value( $array, $array_keys );

Yes, this is certainly possible. The solution would be:

Write a function get_array_value() and pass the original array $json_data and the array of keys $array_keys to this function.
Create a foreach loop inside get_array_value() function that will loop through the $array_keys array. In each iteration of the loop, call another recursive utility function get_array_value_utility().
The get_array_value_utility() function will recursively loop through the array and get the required value from the array.

Here's the code:

function get_array_value_utility($array, $key){
    foreach($array as $k => $v){
        if($key == $k){
            return $v;
        }else if(is_array($v)){
            $v = get_array_value_utility($v, $key);
            if ($v != null) return $v; 
        }
    }
}

function get_array_value($array, $array_keys){
    $values = array();
    foreach($array_keys as $key){
        $values[] = get_array_value_utility($array, $key);
    }
    return $values;
}

$array_keys = array('second_key', 'another_key');
$values = get_array_value($json_data, $array_keys);

// display $values array
var_dump($values);

Here's the live demo (taken from @Evanrose's comment)

edited May 23, 2017 at 11:48

CommunityBot

11 silver badge

answered Oct 16, 2016 at 3:55

Rajdeep Paul

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8 Comments

user6783030 Over a year ago

is this solution is flexible for any level of nesting

Rajdeep Paul Over a year ago

@EaBangalore Yes, this solution is flexible to any level of nesting.

user6783030 Over a year ago

sorry i'm not the owner(questionare)

Rajdeep Paul Over a year ago

@EaBangalore Ah, looks like I need some more coffee. ;-)

Evan Rose Over a year ago

This works great except that the recursive function stops after it gets to the first key that has an array as its value but don't know why. Here's the live demo. Any ideas?

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