Tentando fazer um ORM com UMA CLASSE. HUEHUHE

Model.php

<?php 
namespace Yarkhan\Orm;
use Exception;
use PDO;
/**
 * Nosso humilde e simples ORM. Que não se torne um pesadelo.
 * Funcionalidades descaradamente copiadas de outros ORM's
 */
class Model{
	//Instância PDO
	protected static $_con = null;
	//colunas na tabela do banco de dados
	protected static $_props = [];
	//nome da tabela
	protected static $_table_name = '';
	//nome da coluna da chave primária do bagulho voador
	protected static $_primary_key = null;

	// O plano é que has_many tenha a seguinte estrutura
	// protected static $_has_many = [
	// 	"estados" => [
	// 		"class" => "Vendor\\Package\\Class",
	// 		"junction_table" => "usuario_has_empresa",
	// 		"junction_this_pk" => "usuario_idUsuario"
	// 		"junction_child_pk" => "empresa_idEmpresa"
	// 	]
	// ];

	protected static $_has_many = [];

	public static function setCon(PDO $con){
		self::$_con = $con;
	}
	public static function getCon(){
		if (
			empty(self::$_con) 
			|| empty(static::$_props) 
			|| empty(static::$_table_name)
			|| empty(static::$_primary_key)
		) throw new Exception(
			'Certifique-se de setar corretamente as propriedades do model:
			$_props[array],$_table_name[string],$_primary_key[string],$_con[PDO object]'
		);
		
		return self::$_con;
	}
	/**
	 select * from children
	 join junction_table on chidren.id = junction_table.children_id
	 join parent on parent.id = junction_table.parent_id

	 */
	public function getChildren($children){
		$relation = static::$_children[$children];
		$childClass = $relation['class'];
		// "SELECT ".implode(', ',$childClass::$_props) .
		// " FROM ".$childClass::$_table_name .
		// " JOIN ".$relation['junction_table'] .
		// " ON ".$childClass::$_table_name."."
		$query = static::getCon()->prepare(
			"SELECT ".implode(', ',$childClass::$_props) .
			' FROM :child_table' .
			' join :junction_table on :child_table.pk = :junction_table.child_pk' .
			' join :parent_table on :parent_table.pk = :junction_table.parent_pk' .
			' where :parent_table.pk = :parent_pk'
		);
		//FROM
		$query->bindParam(':child_table',$childClass::$_table_name);
		//1st join
		$query->bindParam(':junction_table',$relation['junction_table']);
		$query->bindParam(':child_table.pk',$childClass::$_table_name.".".$childClass::$_primary_key);
		$query->bindParam(':junction_table.child_pk',$relation['junction_table'].".".$relation["junction_child_pk"]);

		//2st join
		$query->bindParam(':parent_table',static::$_table_name);
		$query->bindParam(':parent_table.pk',static::$_table_name.'.'.static::$_primary_key);
		$query->bindParam(':junction_table.parent_pk',$relation['junction_table'].".".$relation["junction_this_pk"]);

		$query->execute();
		var_dump($query);
	}
	public function getChild(){

	}
	public function getParent(){

	}
	public static function find($id = null){
		$query = static::getCon()->prepare(
			"SELECT ".implode(static::$_props,', ') .
			" FROM ". static::$_table_name .
			" WHERE ".static::$_primary_key." = :id" 
		);
		$query->bindParam(':id',$id);
		$query->execute();
		if($error = $query->errorInfo()[2]) throw new Exception($error);
		return $result = $query->fetchObject(static::class);
	}

	public static function findAll(){
		$query = static::getCon()->prepare(
			"SELECT ".implode(static::$_props,', ') .
			" FROM ". static::$_table_name
		);
		$query->execute();

		return $result = $query->fetchAll(\PDO::FETCH_CLASS,static::class);	
	}

	public function save($id = null){
		if(static::$_primary_key){
			$values = [];
			foreach (static::$_props as $key) {
				$values[] = "$key = :$key";
			}
			$query = static::getCon()->prepare(
				"UPDATE ".static::$_table_name .
				" SET ". implode(', ', $values) .
				" WHERE ".static::$_primary_key." = :id"
			);

			foreach (static::$_props as $key) {
				$query->bindParam(":$key",$this->$key);
			};
			$query->bindParam(":id", $this->{static::$_primary_key},\PDO::PARAM_INT);
			
			return $query->execute();
		}
	}
}