PHP - Error to push Resources from PHP to JSON nested for different resource/dayofweek

The answer below was just an illustration geared towards resolving your issue.

In normal php queries you can do something like this below to get all json data returned by php

<?php

$host = "localhost"; 
$user = "ryour username"; 
$password = "your password"; 
$dbname = "your bd name";

$con = mysqli_connect($host, $user, $password,$dbname);
// Check connection
if (!$con) {
echo "cannot connect to db";
}

$return_arr = array();
$query = "SELECT IDRoom,Nomeroom,Dayofweek,Nome,Aperto,OrarioApertura,OrarioChiusura,Durataminuti FROM room 
    INNER JOIN giorni ON room.IDRoom = giorni.FKRoom 
    INNER JOIN durategame ON room.IDRoom = durategame.FKRoom 
    WHERE room.Statobloccato <> 1";
$result = mysqli_query($con,$query);

while($row = mysqli_fetch_array($result)){
           $IDRoom = $row['IDRoom'];
            $Nomeroom = $row['Nomeroom'];
            $Dayofweek = $row['Dayofweek'];
            $Nome = $row['Nome'];
            $Aperto = $row['Aperto'];
            $OrarioApertura = $row['OrarioApertura'];
            $OrarioChiusura = $row['OrarioChiusura'];
            $Durataminuti = $row['Durataminuti'];



$return_arr[] = array("IDRoom" => $IDRoom,

"Nomeroom" => $Nomeroom,
"Dayofweek" => $Dayofweek,
"Dayofweek" => $Dayofweek,
"Nome" => $Nome,
"Aperto" => $Aperto,
"OrarioChiusura" => $OrarioChiusura,
"OrarioChiusura" => $OrarioChiusura,
"Durataminuti" => $Durataminuti,



);


}

// Encoding array in JSON format
echo json_encode($return_arr);

?>

To help answer your question, you can emulated the code above hence the emulated answer below. Try and see if it helps

//function getMasterBookRoomsaAvailability(){
    $DisponibilitaRoom = [
        'Resource' => null,
        'IntervalTime' => [],
    ];

$return_arr = array();
    $conn = new mysqli($this->servername, $this->username, $this->password,$this->MySQLDB);
    $sql = "SELECT IDRoom,Nomeroom,Dayofweek,Nome,Aperto,OrarioApertura,OrarioChiusura,Durataminuti FROM room 
    INNER JOIN giorni ON room.IDRoom = giorni.FKRoom 
    INNER JOIN durategame ON room.IDRoom = durategame.FKRoom 
    WHERE room.Statobloccato <> 1";

    $result = $conn->query($sql);

    if ($result->num_rows > 0) {

    // output data of each row/*

        while($row = $result->fetch_assoc()) {
            $IDRoom = $row['IDRoom'];
            $Nomeroom = $row['Nomeroom'];
            $Dayofweek = $row['Dayofweek'];
            $Nome = $row['Nome'];
            $Aperto = $row['Aperto'];
            $OrarioApertura = $row['OrarioApertura'];
            $OrarioChiusura = $row['OrarioChiusura'];
            $Durataminuti = $row['Durataminuti'];
            $DisponibilitaRoom['Resource'] = $Nomeroom; 
            $DisponibilitaRoom['IntervalTime'][$Nome] = $this->selectTimesOfDay($OrarioApertura,$OrarioChiusura,$Durataminuti);


$return_arr[] = array("IDRoom" => $IDRoom,

"Nomeroom" => $Nomeroom,
"Dayofweek" => $Dayofweek,
"Dayofweek" => $Dayofweek,
"Nome" => $Nome,
"Aperto" => $Aperto,
"OrarioChiusura" => $OrarioChiusura,
"OrarioChiusura" => $OrarioChiusura,
"DisponibilitaRoom" => $Nomeroom,
"DisponibilitaRoom1" => $this->selectTimesOfDay($OrarioApertura,$OrarioChiusura,$Durataminuti)



);
        }
    }
return $DisponibilitaRoom;
}

// Funzione: prende tutti gli orari di intervallo tra due date splittate dalla durata.
// Params: Array contenente Orario Apertura della room, Orario di chiusura della room, durata prenotabile
// Resultset: restituisce un Array contenente gli orari disponibili
function selectTimesOfDay($startTime,$endTime,$duratagame) {
    $hours = null;
    //var_dump($DisponibilitaRoom);
    $open_time = strtotime($startTime);
    $close_time = strtotime($endTime);
    $duratagame = $duratagame * 60;
    $output = "";
    for( $i=$open_time; $i<$close_time; $i+=$duratagame) {
        //if( $i < $now) continue;
            $output = date("H:i",$i);
            $hours[] = date('H:i', $i);
    }
    return $hours;
//}
echo json_encode($return_arr);