receive returned value by class in oop - php

Question

i have a class like this :
<?php
class connection {
public $db;
public function __construct() {
$this->db = new mysqli('localhost', 'root', '', '');
if($this->db->connect_errno > 0){
die('error ' . $this->db->connect_error);
}
$this->db->set_charset("utf8");
}
}
class masssave extends connection {
public $sql;
public function insert_all {
// do some works
if ( $sql = $this->db->query("INSERT INTO $db_name ($str_db_value) values ($str_form_value_found) ")) {
return true;
}
else {
return false;
}
}
}
?>
in masssave class i seted $sql as public , now i want to use this class in some pages , like register page
$save = new masssave;
if ( $save->sql = true ) {
echo 'ok';
}
else {
echo 'failed';
}
but the upper code is not working , it always echo 'ok' even the query was failed ,
i also use if ( $save->sql == true ) but this code always echo 'failed'
i am newbie in oop , but i think my php classes are ok , i think i am doing wrong way for checking returned value

Answer 1

replace $sql = $this->db->query with $this->sql = $this->db->query -- $sql - local variable. $this->sql - object property
call proper method after $save = new masssave; use $save->insert_all()
use comparison (but not assigment) $save->sql = true - assigment, $save->sql == true - comparison. Assigment reutrns value of variable, so $save->sql = true is always true.

Answer 2

This line should be...
if ( $save->insert_all() == true )
Because....First off, you are just checking if $save->sql is set, which will always echo true in your case.
Also you weren't even checking you were actually setting (= vs ==)
$save = new masssave;
if ( $save->sql = true )
Should be...
$save = new masssave;
if ( $save->sql == true ) {
But that will always return true anyways, because its just checking if the variable exists, which it does. What you really want is what I posted at the top. Because query is actually inside the insert_all function, which is where you are returning true or false.

Answer 3

It will always echo ok because you're setting the $save->sql to true
if ( $save->sql = true ) {
The above is a big NO NO.
What you want is to compare it, so using == to compare the values
if ( $save->sql == true ) {
It would be simpler to just do:
if($save->sql) {
echo 'ok;
} else {
echo 'fail';
}
the above if check is basically saying IF(TRUE) { SAY OK} ELSE { SAY FAIL}