I have the following JSON object:

{
    "id": 1,
    "name": null,
    "block": {
        "type": "none",
        "descends": [
            {
                "operation":"sum",
                "descends":[
                    {
                        "label":2,
                        "value":false
                    }
                ]
            },
            {
                "label": 1,
                "value": 3,
            },
            {
                "label": 2,
                "value": 2
            }
        ],
        "label": 1,
        "value": true
    }
}

I want to collect all the label and value attributes and store them in an array, so I created the following function:

public function collectValues($arr){
    $finalValues = [];
    foreach($arr as $key => $element){
        if($key=='block'){
            foreach($element as $key2 => $block){
                if($key2=='descends'){
                    foreach($block as $key3 => $node_block){
                        if($key3=='descends'){
                            foreach($node_block as $key4 => $anotherNode){
                                
                                if($key4 == 'descends'){
                                    foreach($anotherNode as $finalNode){
                                        $finalValues [] = array('lable'=>$finalNode->label, 'value' =>$finalNode->value);
                                    }

                                }
                            }
                            
                        }
                        else{
                            $finalValues [] = array('lable' => $node_block->label, 'value' => $node_block->value);
                        }
                    }
                }
            }

            $finalValues [] = array('lable'=> $element->label, 'value' => $element->value);
        }
    }

    return $finalValues;
}

The function works and I get the following:

[
    {
        "lable": 2,
        "value": false
    },
    {
        "lable": 1,
        "value": 3
    },
    {
        "lable": 2,
        "value": 2
    },
    {
        "lable": 1,
        "value": true
    }
]

The problem is that the JSON object can contain more descends like:

{
    "id": 1,
    "name": null,
    "block": {
        "type": "none",
        "descends": [
            {
                "operation":"sum",
                "descends":[
                    {
                        "operation":"sum",
                        "descends":[
                            {
                                "label":2,
                                "value":false
                            }
                        ],
                        "label":2,
                        "value":false
                    }
                ]
            },
            {
                "operation":"sum",
                "descends":[
                    {
                        "label":2,
                        "value":false
                    }
                ],
                "label": 1,
                "value": 3,
            },
            {
                "label": 2,
                "value": 2
            }
        ],
        "label": 1,
        "value": true
    }
}

This means I will have to add more foreach loops. A good way to handle such a situation is by using recursive. How can I transform the function above into a recursive one?

CodePudding user response：

Your looped function does not make sense to change. Easier to rewrite from scratch Here is my use case for recursion. Maybe there is an easier option, but I didn’t chase optimization

$array = json_decode($json, true); //in $json your JSON)
$result = []; // array for result
checkLabel($array, $result);
print_r($result);

function checkLabel(array $array, &$result){ 
    //first check every element on nested array
    foreach ($array as $key => $value){

        if (is_array($value)) {
            //if found call recursive function
            checkLabel($value, $result);
        }
    }
    //then check 'label' key.. its mean we have attribute
    if (array_key_exists('label', $array)) {
        //save it
        $result[] = [
            'label' => $array['label'],
            'value' => $array['value']??'' //if have label but without value)
        ];
    }
}