PDO - FETCH_CLASS - pass results to constructor as parameters - php

Question

Is there any way, to pass results of PDO as parameters of the constructor?
Let's say, I have the following class:
class Test
{
private $value1;
private $value2;
function __construct($val1, $val2)
{
$this->value1 = $val1; $this->value2 = $val2;
}
}
Then, via PDO driver I select some data from DB, let's say:
SELECT price, quantity FROM stock
$results = $query->fetchAll(PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, "Test");
Right now, PDO passess these values directly to the class fields, and bypassing the constructor.
Maybe I am missing something, but I want to pass results from the query to the constructor.
Constructor cannot be query-dependent, I want to be able to instantiate this class even without using PDO.

Answer 1

The only way I figured out was using FETCH_FUNC constant and providing a function to create the object through the constructor.
function rowMapper( $price, $quantity)
{
return new Test( $price, $quantity);
}
$results = $query->fetchAll( PDO::FETCH_FUNC, "rowMapper");
Now your objects will only be created using your constructor, instead of having PDO injecting values in private data and breaking the encapsulation.

Answer 2

Maybe I am missing something, but I want to pass results from the query to the constructor.
Results from the query can be assigned to your object properties directly with PDO::FETCH_CLASS
we also need a constructor able to overwrite values from PDO if needed, so remove PDO::FETCH_PROPS_LATE from the fetch.
function __construct($val1=null, $val2=null) {
// now the constructor is called after the fetch
// if you pass values to it, they will be assigned
if ($val1!==null) $this->price = $val1;
if ($val2!==null) $this->quantity = $val2;
}
we have two ways of instantiating the object
PDO
$stmt = $db->prepare('SELECT price, quantity FROM stock');
$stmt->setFetchMode(PDO::FETCH_CLASS,'Test');
$result = $stmt->fetch();
new
$result = new Test(25,100);
if you want to work with the values which come from the database, you can do so in the constructor, still leaving FETCH_PROPS_LATE out.
function __construct($val1=null, $val2=null) {
if ($val1!==null) $this->price = $val1;
if ($val2!==null) $this->quantity = $val2;
$this->formattedPrice = number_format($this->price,'2');
}

Answer 3

I ran into this situation while building a PDO Repository for my entities. I don't use this approach because I don't like having to match the parameters one to one. This was the closest I could get to mimicking a constructor, by using a static factory pattern.
class User
{
private $id;
public $name;
public $isMinor;
// make sure parameters are in the same order as the mysql result
public static function buildFromPdo($id, $age, $name)
{
$user = new self;
$user->id = $id;
$user->name = $name;
$user->isMinor = $age < 18;
return $user;
}
public function getId()
{
return $this->id;
}
}
$stmt = $db->prepare('SELECT id, age, name FROM users');
$stmt->execute();
$result = $stmt->fetchAll(PDO::FETCH_FUNC, "User::buildFromPdo");
"$result" will be an array of User objects.

Answer 4

[I edited this answer as my previous answer is not accurate anymore.]
FETCH_CLASS does fetch into private properties. Please refer to this answer.

Answer 5

In your case you could pass them like this:
$results = $query->fetchAll(PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, "Test", array('val1', 'val1'));
Read about the 3rd parameter for fetchAll() here.

Answer 6

Use PdoObject::fetchAll(\PDO::FETCH_CLASS), this will return what exactly you are wanting.
Nevertheless, if you need something specific to pass follow the below code snippet
$sql = "SELECT * FROM ".$table. " WHERE id=$id";
$sth = $dbAdapter->prepare($sql);
$sth->execute();
//inject anything you want
$result = $sth->fetchAll(\PDO::FETCH_CLASS, $tableClass, array($pass1, $pass2, $dbAdapter));