Creating an array of objects in PHP with for loop

Question

I am trying to get data from mysql data, create objects from it. Here I have written some code. I am getting thing's details from a database. Now for each result I want an object to be created which is finally merged with an array output. This $output array is finally outputted as json.

I am getting error :

array_merge(): Argument #2 is not an array

How to create arrays of objects in PHP ?

public function getDetails()    //This is a class function
{
    $query = "SELECT * FROM `thing` WHERE `id` = :thingId";
    $stmt = $dbh->prepare ( $query );
    $stmt->bindParam ( ":thingId" , $_GET['thingId']  );
    $stmt->execute ( );
    $rslt  =  $stmt->fetch ( );
    $thingName  = $rslt['name'];
    $thingOwnerId = $rslt['userId'];
    $thingDescription = $rslt['thingDescription'];

    // Getting the thing owner details
    $query = "SELECT * from `user` WHERE ( `id` = :id ) ";    
    $stmt = $dbh->prepare( $query );
    $stmt->bindParam ( ":id" , $thingOwnerId );
    $stmt->execute(  );
    $rslt = $stmt->fetch ( );
    $thingOwnerName = $rslt['firstName']." ".$rslt['lastName'];
}

$query = "SELECT * FROM `things` ; ";
$s = $dbh->prepare($query);
$s->execute();
$r = $s->fetchAll();
foreach($r as $r1)
{
    $newThing = new Thingy($r1['id']);
    $newThing->getDetails();
    $output =  array_merge($output,$newThing);
}

$output2 = json_encode($output);
header('content-type: application/json');
echo $output2;

And where you've defined your parameter#2 i.e. $newRoute ? — Alma Do
– Alma Do, Commented Nov 8, 2013 at 12:40
You have not defined variable $newRoute so it value is undefined and array_merge requires arguments as array so php fires error. — Hardeep Pandya
– Hardeep Pandya, Commented Nov 8, 2013 at 12:41

Jesper Blaase · Accepted Answer · 2013-11-08 12:44:36Z

1

You could do the following:

$output = [];
foreach($r as $r1)
{
    $newThing = new Thingy($r1['id']);
    $newThing->getDetails();
    $output[] = $newThing;
}

answered Nov 8, 2013 at 12:44

Jesper Blaase

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Comments

Darragh Enright · Accepted Answer · 2013-11-08 12:55:48Z

1

You could save yourself some work here and use PDO::FETCH_CLASS as the $fetch_style. Basically it allows you to specify a custom class, the properties of which you can populate with matching return values from each row in your query. Note the first argument in the method signature:

public array PDOStatement::fetchAll ([ int $fetch_style [, mixed $fetch_argument [, array $ctor_args = array() ]]] )

As illustrated in example #4 from the PDOStatement::fetchAll() documentation

<?php
class fruit {
    public $name;
    public $colour;
}

$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();

$result = $sth->fetchAll(PDO::FETCH_CLASS, "fruit");
var_dump($result);

Hope this helps :)

answered Nov 8, 2013 at 12:55

Darragh Enright

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2 Comments

Ateev Chopra Over a year ago

Thanks ! Thats really helpful ! But I am getting data from multiple tables. And creating a single object out of it. Will it work in that case ?

Darragh Enright Over a year ago

Yes it should be completely fine, all you need is an object with the same properties as the columns you are returning from your database - this can be from one or many tables - you are mapping the returned data to the object, so PHP does not care about the underlying table structure. It's a pretty useful feature imho!

Community · Accepted Answer · 2023-11-17 20:33:26Z

0

I see a couple things that could potentially be causing problems.

First, and likely the cause of your issues, is that array_merge only accepts arguments of type array. See the documentation. However, you can either cast the type of $newThing to be an array, or more succinctly just do a manual append as suggested in this other answer.

Second, your method getDetails() neither returns anything, nor does is it a class method that modifies an object's contents. It needs to be one or the other; right now it runs and the results aren't permanently stored anywhere. Since you've indicated it's a class method, then it should look like this:

public function getDetails()    //This is a class function
{
    $query = "SELECT * FROM `thing` WHERE `id` = :thingId";
    $stmt = $dbh->prepare ( $query );
    $stmt->bindParam ( ":thingId" , $_GET['thingId']  );
    $stmt->execute ( );
    $rslt  =  $stmt->fetch ( );
    $this->thingName  = $rslt['name'];                    // Class variable
    $this->thingOwnerId = $rslt['userId'];                // Class variable
    $this->thingDescription = $rslt['thingDescription'];  // Class variable

    // Getting the thing owner details
    $query = "SELECT * from `user` WHERE ( `id` = :id ) ";    
    $stmt = $dbh->prepare( $query );
    $stmt->bindParam ( ":id" , $thingOwnerId );
    $stmt->execute(  );
    $rslt = $stmt->fetch ( );
    $this->thingOwnerName = $rslt['firstName']." ".$rslt['lastName']; // Class variable
}

edited Nov 17, 2023 at 20:33

CommunityBot

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answered Nov 8, 2013 at 12:43

Magsol

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2 Comments

Ateev Chopra Over a year ago

Updated my question. $newRoute isn't the problem. Also, the getDetails() doesn't returns anything but it does defines many attributes of the object created.

Magsol Over a year ago

It's not a class method, so it's not modifying any attributes either. Unless you omitted the class definitions and use of $this-> before posting your code?

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