Merge two JSON array in PHP

Question

I need to merge two json file in PHP . One is at first empty, and the other one changes at each call.

I found a lot of codes to merge two JSON array into one in PHP but it doesn't work for me.

$final_array = array();
$first_json = file_get_contents("test3.json");
$second_json = file_get_contents("my-file.json");


if(json_decode($first_json,true) == null){
    $final_array[] = json_decode($second_json,true);
    $merge_final_array = json_encode(json_decode($second_json,true));
}else{
    $final_array[] = json_decode($first_json,true);
    $final_array[] = json_decode($second_json,true);
    $merge_final_array = json_encode($final_array);
}

file_put_contents("test3.json", $merge_final_array);
$merge_final_array = null;

I add recursively to the "test3.json" file the data that I find in the "my-file.json".

This should give me :

[{"score":15,"win":true,"device":"Android SDK built for x86"},{"score":"Finish","device":"Android SDK built for x86","win":true},{"win":true,"score":"Finish","device":"Android SDK built for x86"},{"score":16,"scenario":"Finish","win":true,"device":"Android SDK built for x86"}]

As it gives me:

[[[{"score":15,"win":true,"device":"Android SDK built for x86"},{"score":"Finish","device":"Android SDK built for x86","win":true}],{"win":true,"score":"Finish","device":"Android SDK built for x86"}],{"score":16,"scenario":"Finish","win":true,"device":"Android SDK built for x86"}]

I also tried the method json_encode(array_merge(json_decode($first_json, true),json_decode($second_json, true))) It gives me this : Code + result

What did I do wrong?

Answer 1

You first need to convert your JSON to arrays before you can do anything with it in PHP .

First you need to create a new empty array in PHP and add the JSON arrays to that empty array.
Then encode the array again to JSON and write it to a file.
Your full code:

$first_json = file_get_contents("test3.json");
$second_json = file_get_contents("my-file.json");

$first_array = json_decode($first_json, true); // make array of json
$second_array = json_decode($second_json, true); // make array of json

$final_array = array(); // create an empty array 
$final_array[] = $first_array; // add first array to empty array
$final_array[] = $second_array;  // add second array to array

$final_json = json_encode($final_array); // make a json from the array again

file_put_contents("test3.json", $final_json); // put the json inside a new file 

Answer 2

Here is what you want:

<?php

$finalArray = [];

// file_get_contents("test3.json");
$firstFileContent = '{"score":15,"win":true,"device":"Android SDK built for x86"}';

// file_get_contents("my-file.json")
$secondFileContent = '{"score":"Finish","device":"Android SDK built for x86","win":true}';

$firstJson = json_decode($firstFileContent, true);
if(JSON_ERROR_NONE === json_last_error()){
    $finalArray[] = $firstJson;
}

$finalArray[] = json_decode($secondFileContent, true);

$finalJson = json_encode($finalArray);

http://sandbox.onlinephpfunctions.com/code/404972fb59b4f7323f81ee444a1cb14f772f7748

It gives me this : Code + result

It's all because of you do array_merge of two arrays and second one will rewrite the first values. You should add second array to the result array, not merge.

array_merge(["a" => 1], ["a" => 2]) // result: ["a" => 2]

$result[] = ["a" => 1];
$result[] = ["a" => 2];
// result: [["a" => 1], ["a" => 2]]

json_encode(array_merge(json_decode($first_json, true),json_decode($second_json, true)))

This will not work, because in each file you have encoded object , not array of objects. If you have in first file {"a":1} and in second file {"a":2} , when you'd merge their decoded values the result will be {"a":2} , but if you'd edit them to [{"a": 1}] and [{"a": 2}] , the the result will be [{"a": 1}, {"a": 2}] because now you to merge the array of objects converted to array, not objects.

---

If you want to add the data from both files recursively, you should do something like this:

<?php

$finalArray = [];

$firstFileContent = '[[{"score":15,"win":true,"device":"Android SDK built for x86"},{"score":"Finish","device":"Android SDK built for x86","win":true}],{"win":true,"score":"Finish","device":"Android SDK built for x86"}]';
$secondFileContent = '{"score":16,"scenario":"Finish","win":true,"device":"Android SDK built for x86"}';

mergeJsonRecursively($finalArray, $firstFileContent);
mergeJsonRecursively($finalArray, $secondFileContent);

function mergeJsonRecursively(array &$result, string $json)
{
    $decodedJson = json_decode($json);
    if (JSON_ERROR_NONE === json_last_error()) {
        tryToAddElementToResult($result, $decodedJson);

        if (is_array($decodedJson)) {
            foreach ($decodedJson as $element) {
                tryToAddElementToResult($result, $element);

                if (is_array($element)) {
                    mergeJsonRecursively($result, json_encode($element));
                }
            }
        }
    }
}

function tryToAddElementToResult(array &$result, $element)
{
    if (is_object($element)) {
        $result[] = json_decode(json_encode($element), true);
    }
}

$finalJson = json_encode($finalArray);

http://sandbox.onlinephpfunctions.com/code/f4858bcc87da34e4ee6639b2ee96c7ac3244ae1b

And you will give expected result:

[{"score":15,"win":true,"device":"Android SDK built for x86"},{"score":"Finish","device":"Android SDK built for x86","win":true},{"win":true,"score":"Finish","device":"Android SDK built for x86"},{"score":16,"scenario":"Finish","win":true,"device":"Android SDK built for x86"}]

Answer 3

Just simply do this. You can add you own Error handling but the basic should be like :

$final_array = array();
$first_json = file_get_contents("test3.json");
$second_json = file_get_contents("my-file.json");

$first_array = json_decode($first_json,true);
$second_array = json_decode($second_json,true);

if(is_array($first_array) and is_array(second_array)){
    $final_array = array_merge(first_array,second_array);
}
else if(!empty($first_array) and is_array($first_array)){
    $final_array = $first_array;
}
else if(!empty(second_array) and is_array(second_array)){
    $final_array = second_array;
}

$final_json = json_encode(final_array);

file_put_contents("test3.json", final_json);