Not getting desired output from PHP class - php

Question

This is my very first question actually. I am under a learning process of OOP PHP and trying to design my first class for Category. Here is my code
<?php
class category{
public $catid;
public $datacol;
public function __construct($catid=0)
{
$this->catid=0;
$this->datacol=$this->load($catid);
}
public function load($catid)
{
global $conn;
$sql=' select * '
.' FROM tbl_categories'
.' WHERE catid='.$catid;
if (!($res=mysqli_query($conn,$sql)) || !mysqli_num_rows($res)>0)
return false;
$this->datacol = mysqli_fetch_array($res);
$this->catid = $this->datacol['catid'];
return true;
}
public function reload() {
return $this->load($this->getId());
}
/* ------------------> Getter methods <--------------------- */
public function getId() { return $this->catid; }
public function getName() { return $this->datacol['category']; }
public function getOneliner() { return $this->datacol['categoryoneliner']; }
public function getBrief() { return $this->datacol['categorybrief']; }
public function getThumb() { return $this->datacol['timg']; }
public function getImage() { return $this->datacol['limg']; }
public function getParentID() { return $this->datacol['parentcat']; }
public function getPagetitle() { return $this->datacol['catpagetitle']; }
public function getKeywords() { return $this->datacol['catkeywords']; }
public function getMetadesc() { return $this->datacol['categorymetadesc']; }
public function getPriority() { return $this->datacol['priority']; }
public function getRemarks() { return ($this->datacol['remarks']); }
public function getRow() { return $this->datacol; }
}
?>
Now,
When i create its object from other file with a code as below:
$cat=new category(10);
echo var_dump($cat);
echo var_dump($cat->getId());
echo var_dump($cat->getName());
The output gives me the correct catid when called getID(). But Shows NULL for getName() or any other function other than getID().
What am i doing wrong?
Thanks in advance

Answer 1

As #Arnold Gandarillas said, you are overwriting $datacol in the constructor.
Your constructor calls load(), which sets $datacol:
public function load($catid)
{
...
$this->datacol = mysqli_fetch_array($res);
return true;
}
The function then returns true. In the constructor, this true is assigned to $datacol, overwriting the previous value:
public function __construct($catid=0)
{
$this->catid=0;
$this->datacol=$this->load($catid);
}
Change the constructor to something like this:
public function __construct($catid=0)
{
if ($catid > 0)
$this->load($catid);
}

Answer 2

Alright - look closely to your function:
public function load($catid)
{
global $conn;
$sql=' select * '
.' FROM tbl_categories'
.' WHERE catid='.$catid;
if (!($res=mysqli_query($conn,$sql)) || !mysqli_num_rows($res)>0)
return false;
$this->datacol = mysqli_fetch_array($res);
$this->catid = $this->datacol['catid'];
return true;
}
So, you function returns either true of false. And this boolean values is assgined to $this->datacol here:
$this->datacol = $this->load($catid);
As this assignment happens after you did $this->datacol = mysqli_fetch_array($res);, your $this->datacol becomes either true or false, and holds no real data from mysql.
So, one of the solutions can be to remove assignment:
public function __construct($catid=0)
{
$this->catid=0;
$this->load($catid);
}
In this case your $this->datacol is not overwritten.

Answer 3

its simple $this->datacol = $this->load($catid); is not required
you have assigning $this->datacol twice
public function __construct($catid=0)
{
$this->catid=0;
$this->load($catid);
}
public function load($catid)
{
global $conn;
$sql=' select * '
.' FROM tbl_categories'
.' WHERE catid='.$catid;
if (!($res=mysqli_query($conn,$sql)) || !mysqli_num_rows($res)>0)
return false;
$this->datacol = mysqli_fetch_array($res);
$this->catid = $this->datacol['catid'];
return true;
}
please add if anything is missing