Assign object attributes from the result of prepared statement - php

Question

I'm wanting to create a new instance of my Class and assign it's attributes the values that are returned. The reason for this is I'm creating a series of methods inheriting from the calling class, as opposed to using static methods which I already had working.
Example of what I'm using currently:
public static function findById($id) {
$id = self::escapeParam($id);
$idVal = is_int($id) ? "i" : "s";
$sql = "SELECT * FROM ".static::$db_table." WHERE id = ? LIMIT 1";
return static::findByQuery($sql,$idVal,$id);
}
public static function findByQuery($sql,$bindChar = '',$bindVal = '') {
try {
$callingClass = get_called_class();
$object = new $callingClass;
$statement = Database::$connection->prepare($sql);
if(!empty($bindChar)) :
$statement->bind_param($bindChar, $bindVal);
endif;
if($statement->execute()) :
$result = $statement->get_result();
$object = $result->fetch_object();
endif;
$statement->close();
if(!empty($object)) :
return $object;
endif;
} catch(Exception $e) {
}
}
What I tried was writing an instantiation method that creates a new instance of my class, and then assign each attribute of the object the value it returns from an array from a tutorial I did. However, the tutorial was fairly outdated and didn't use any new syntax or binding, so I was trying to rework this.
Example from the tutorial below:
public static function find_by_id($id) {
global $database;
$the_result_array = static::find_by_query("SELECT * FROM " . static::$db_table . " WHERE id = $id LIMIT 1");
return !empty($the_result_array) ? array_shift($the_result_array) : false;
}
public static function find_by_query($sql) {
global $database;
$result_set = $database->query($sql);
$the_object_array = array();
while($row = mysqli_fetch_array($result_set)) {
$the_object_array[] = static::instantation($row);
}
return $the_object_array;
}
public static function instantation($the_record){
$calling_class = get_called_class();
$the_object = new $calling_class;
foreach ($the_record as $the_attribute => $value) {
if($the_object->has_the_attribute($the_attribute)) {
$the_object->$the_attribute = $value;
}
}
return $the_object;
}
private function has_the_attribute($the_attribute) {
return property_exists($this, $the_attribute);
}
What I was trying to do from the tutorial, was to return my result as an array using a while, and then assigning a variable by passing the built array into the static::instantation() method, but it doesn't seem to ever be working correctly, as any public functions I create in my calling class (Admin for example) aren't called after as they don't exist due to the Class not being instantiated.

Answer 1

mysqli_result::fetch_object() accepts the class name as the first argument. You can pass the class name as an argument to that method and get the instance of the model. I am not sure why you have that much code but consider my example which I wrote based on your own code:
<?php
class Model
{
public static function findByQuery(string $sql, ?string $bindChar = null, ?string $bindVal = null): ?static
{
$statement = Database::$connection->prepare($sql);
if ($bindChar) :
$statement->bind_param($bindChar, $bindVal);
endif;
$statement->execute();
$result = $statement->get_result();
return $result->fetch_object(static::class);
}
}
class User extends Model
{
private $id;
}
class Database
{
public static mysqli $connection;
}
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
Database::$connection = new mysqli('localhost', 'user', 'password', 'test');
$user = User::findByQuery('SELECT ? as id', 's', 'Dharman');
var_dump($user);
The output from that example is:
object(User)#4 (1) {
["id":"User":private]=>
string(7) "Dharman"
}
As you can see, the code created an instance of the class using late-static binding and it also assigned the value to a private property, which you can't do otherwise.
P.S. My example is a little bit tidier. I added parameter typing and removed a lot of unnecessary code. In particular, I remove empty try-catch which is a terrible practice.

Answer 2

I have now got this working, although I feel this is probably not the best way of doing it.
I'm primarily front end so please comment if there are improvements or best practices.
public static function findByQuery($sql,$bindChar = '',$bindVal = '') {
try {
$statement = Database::$connection->prepare($sql);
if(!empty($bindChar)) :
$statement->bind_param("$bindChar", $bindVal);
endif;
if($statement->execute()) :
$result = $statement->get_result();
$output = $result->fetch_object();
endif;
$statement->close();
if(!empty($output)) :
$class = get_called_class();
$object = new $class;
foreach(get_object_vars($output) as $key => $value) :
$object->$key = $value;
endforeach;
endif;
if(!empty($object)) :
return $object;
endif;
} catch(Exception $e) {
}
}
My initial thoughts were declaring an object and then I thought that the PHP fetch_object call would have just assigned my object it's properties after initiating the Class but that wasn't the case.
So what I've done is that if the statement is successful and a results object is created, I then get the object properties and values with the get_object_vars() command, and then loop through these as a key value pair, assigning each attribute it's returned value.
I can confirm this works as I can now run $admin->remove() from my removal script, as opposed to what I was having to do before which was Admin::remove($id);