How to create PHP custom nested json array with flat json result array

Question

I am trying to create an array of custom json objects while traversing an array of results from a db query. However I m unable to get the correct response from the code.

I have tried creating arrays and traversing it. Below is my code to show what all I have tried. P.S. I am newbie to php so, I am sorry if its a rookie mistake or anything.

$response = array();
    while($row = $result->fetch_assoc()){
        $flag = false;
        $sample_obj = json_encode(json_decode("{}"));
        $index = 0;
        $length = count($response);
        for($x = 0; $x < $length; $x++){
            if($response[$x]->session_id == $row->session_id){
                $sample_obj = $row;
                $flag = true;
                $index = $x;
                break;
            }
        }
        if($flag == true){
            $sample_array = array();
            $sample_array[] = $row;
            $response[$index]->sessions[] = $row;
        } else {
            $sample_array = array();
            $sample_array[] = $row;
            $sample_obj["session_id"] = $row->session_id;
            $sample_obj["sessions"] = array();
            $sample_obj["sessions"] = $sample_array;
            $response[] = $sample_obj;
        }
        // $response[] = $row;
    }
    $res["statusCode"] = 201;
    $res["success"] = true;
    $res["records_found"] = true;
    $res["results"] = $response;
    header('Content-Type: application/json;charset:utf-8');
    echo json_encode($res,JSON_PRETTY_PRINT);

I want output like

{
    "statusCode": 201,
    "success": true,
    "records_found": true,
    "results": [
        {
            "session_id" : 1,
             "sessions"  : [
              {
                   "session_id" : 1,
                   "creation_time" : "some_timestamp",
                    "active_session" : true
              },

              {
                   "session_id" : 1,
                   "creation_time" : "some_timestamp",
                    "active_session" : false
              },

              {
                   "session_id" : 1,
                   "creation_time" : "some_timestamp",
                    "active_session" : false
              }
              ]
        }
    ]
}

But I m getting very wrong output like :

{
    "statusCode": 201,
    "success": true,
    "records_found": true,
    "results": [
        "A}"
    ]
}

I dont know why this "A}" is being shown instead of my session array.

MaartenDev · Accepted Answer · 2019-08-26 09:02:56Z

The following line causes errors.

    $sample_obj = json_encode(json_decode("{}"));

Replacing it with:

 $sample_obj = [];

would fix the problem.

Checkout the following working example:

<?php
$response = array();
while($row = $result->fetch_assoc()){
    $flag = false;
    $sample_obj = [];
    $index = 0;
    $length = count($response);
    for($x = 0; $x < $length; $x++){
        if($response[$x]->session_id == $row->session_id){
            $sample_obj = $row;
            $flag = true;
            $index = $x;
            break;
        }
    }
    if($flag == true){
        $sample_array = array();
        $sample_array[] = $row;
        $response[$index]->sessions[] = $row;
    } else {
        $sample_array = array();
        $sample_array[] = $row;
        $sample_obj["session_id"] = $row->session_id;
        $sample_obj["sessions"] = array();
        $sample_obj["sessions"] = $sample_array;
        $response[] = $sample_obj;
    }
    // $response[] = $row;
}
$res["statusCode"] = 201;
$res["success"] = true;
$res["records_found"] = true;
$res["results"] = $response;
header('Content-Type: application/json;charset:utf-8');
echo json_encode($res,JSON_PRETTY_PRINT);

or with sample data:

$rows = [(object)['session_id' => 1]];
$response = [(object)['session_id' => 2]];
foreach($rows as $row){
    $flag = false;
    $sample_obj = [];
    $index = 0;
    $length = count($response);
    for($x = 0; $x < $length; $x++){
        if($response[$x]->session_id == $row->session_id){
            $sample_obj = $row;
            $flag = true;
            $index = $x;
            break;
        }
    }
    if($flag == true){
        $sample_array = array();
        $sample_array[] = $row;
        $response[$index]->sessions[] = $row;
    } else {
        $sample_array = array();
        $sample_array[] = $row;
        $sample_obj["session_id"] = $row->session_id;
        $sample_obj["sessions"] = array();
        $sample_obj["sessions"] = $sample_array;
        $response[] = $sample_obj;
    }
    // $response[] = $row;
}
$res["statusCode"] = 201;
$res["success"] = true;
$res["records_found"] = true;
$res["results"] = $response;
header('Content-Type: application/json;charset:utf-8');
echo json_encode($res,JSON_PRETTY_PRINT);

era-net · Accepted Answer · 2019-08-26 09:52:28Z

0

you can prewrite what ever you want in a php array like this:

$arr = array(
    "val_1" => "value1",
    "val_2" => "value2",
    "val_3" => array(
        "moreVals" => "another value",
        "smtng" => "smtng"
    )
);

and than convert it to json like so:

$json = json_encode($arr, JSON_PRETTY_PRINT | JSON_FORCE_OBJECT);

I use this method all the time and it works fine for me.

I hope, it hepls.

answered Aug 26, 2019 at 9:52

era-net

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