Issue with Nested JSON in PHP

Does this code example help you?

PHP objects will be converted into a JSON Object which is the {} part.
PHP array will be converted into a JSON Array which is offcource the [] part.

PHP code

<?php

$StdClass = new StdClass();
$StdClass->length = 10;
$StdClass->schools = array_values(array(1, 2));

var_dump(json_encode($StdClass));

?>

Result

string(29) "{"length":10,"schools":[1,2]}"

Edited because off comment:

Thank you for your quick reply, but sadly, I'm having a real tough time figuring that out. Also, there are all of these 'character counts' that I can't use.

Yes getting the [{..}] JSON format for schools and students it more tricky.
I advice you writing custom classes and use JsonSerializable to convert your custom Objects into JSON

PHP 7 code

<?php

class school implements JsonSerializable {
  private $name = null;
  private $students = array();

  private function __construct() {

  }

  public function __destruct() {
      $this->name = null;
      $this->students = null;
  }  

  // Use a static object because it will enable method chaining
  public static function getInstance() {
      return new school();
  }

  public function setName(string $name) : school { 
      $this->name = $name;
      return $this; // needed to chain
  }

  public function setStudent(Student $student) : school { 
      $this->students[] = $student;
      return $this; // needed to chain
  }  

  public function getName() : ?string {
      return $this->name;
  }

  public function getStudents() : ?array {
      return $this->students;
  }  

  public function __get($name) : mixed {
      return $this->name;
  }

  public function jsonSerialize() {
    return array(
        "name" => $this->name
      , "students" => $this->students
    );
  }  
}

class student implements JsonSerializable {
  private $lastname = null; 
  private $firstname = null;

  private function __construct() {

  }

  public function __destruct() {
      $this->lastname = null;
      $this->firstname = null;
  }

  // Use a static object because it will enable method chaining
  public static function getInstance() {
      return new student();
  }  

  public function setLastName(string $lastname) : student { 
      $this->lastname = $lastname;
      return $this; // needed to chain
  }  

  public function setFirstName(string $firstname) : student { 
      $this->firstname = $firstname;
      return $this; // needed to chain
  } 

  public function getFirstName() : ?string {
      return $this->firstname;
  }

  public function getLastName() : ?string {
      return $this->lastname;
  }  

  public function jsonSerialize() {
    return array(
        "lastname" => $this->lastname
      , "firstname" => $this->firstname
    );  
  }
}

$json = new stdClass();
$json->length = 10;


$json->schools = array(
    school::getInstance()
          ->setName('Test High School')
          ->setStudent(
              student::getInstance()
                     ->setFirstname('Smith') 
                     ->setLastname('Allison')
          )
          ->setStudent(
              student::getInstance()
                     ->setFirstname('Jones') 
                     ->setLastname('Derek')
          )          
    , 
    school::getInstance()
          ->setName('Test Elementary School')    
          ->setStudent(
              student::getInstance()
                     ->setFirstname('Jones') 
                     ->setLastname('Emmett')  
         ) 
);

var_dump(json_encode($json));

?>

p.s to get the code working on lower PHP versions remove the PHP's return type declarations

Results in this JSON format

{
    "length": 10,
    "schools": [{
        "name": "Test High School",
        "students": [{
            "lastname": "Allison",
            "firstname": "Smith"
        }, {
            "lastname": "Derek",
            "firstname": "Jones"
        }]
    }, {
        "name": "Test Elementary School",
        "students": [{
            "lastname": "Emmett",
            "firstname": "Jones"
        }]
    }]
}