public function readJson($check_header = true, $override = false)
	{
		if( !is_null($this->from_json) && !$override )
		{
			return $this->from_json;
		}

		// set false json reader
		$this->from_json = false;

		if( $check_header )
		{
			$type = $this->server->getIs("CONTENT_TYPE") ? $this->server->get("CONTENT_TYPE") : $this->server->getOr("HTTP_ACCEPT", '');
			if( ! preg_match('/(?:application|text)\/json(?:$|;| )/', $type) )
			{
				return false;
			}
		}

		$body = $this->body();
		if( strlen($body) && ( $body[0] === "{" || $body[0] === "[" ) )
		{
			$this->params_post = new Collection( Json::parse($body, true) );
			$this->body = '';
			$this->from_json = true;
		}

		return $this->from_json;
	}