Question

Update
As per the instruction of experts, I’ve modified the code this way:

<?php
//Class Validation
class transaction_validate{
    
private $val_id;
    function __construct($id) {
        $this->val_id = $id;
    }

public function status(){
    //Call our server and decode json value
    $data = $this->get_data($this->val_id);
    $obj = json_decode($data);

    return $obj->status;
}

public function amount(){
    //Call our server and decode json value
    $data = $this->get_data($this->val_id);
    $obj = json_decode($data);

    return $obj->amount;
}


//Create a function for fetching data
private function get_data($sid){
    $url = 'https://domain.com/verify/process.php?trx='.$sid;
    $ch = curl_init();
    $timeout = 5;
    curl_setopt($ch,CURLOPT_URL,$url);
    curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
    curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,$timeout);
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}
}

$validate = new transaction_validate();
$validate->val_id = '5201211120944';
echo $validate->amount();
echo '<br>';
echo $validate->status();

And output is

Warning: Missing argument 1 for transaction_validate::__construct(),

Fatal error: Cannot access private property transaction_validate::$val_id

Confused!

============================Previous Question======================================

I’m just learning OOP style PHP coding. Tried to code a script for personal usage which seems wrong. Code is:

<?php
//Class Validation
class transaction_validate{
    
    var $val_id;
    
    public function status(){
        //Call our server and decore json value
        $data = get_data();
        $obj = json_decode($data);
        
        return $obj->status;
    }
    
    public function amount(){
        //Call our server and decore json value
        $data = get_data();
        $obj = json_decode($data);
        
        return $obj->amount;
    }

    
    //Create a function for featching data
    private function get_data($val_id){
        $url = 'https://domain.com/verify/process.php?trx='.$val_id;
        $ch = curl_init();
        $timeout = 5;
        curl_setopt($ch,CURLOPT_URL,$url);
        curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
        curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,$timeout);
        $data = curl_exec($ch);
        curl_close($ch);
        return $data;
    }
}

$validate = new transaction_validate('5201211120944');
echo $validate->amount();
echo '<br>';
echo $validate->status();

And output is

Fatal error: Call to undefined function get_data() in
/home/userdo/public_html/class.php on line 17

I need to recognize what wrong I did.

Answer 1

You need to tell PHP the function is in the class context:

$this->get_data()

As mentioned in comments, you should add a constructor to set the id you are passing in…

class transaction_validate{

    private $val_id;

    function __construct($id) {
        $this->val_id = $id;
    }

    //...

Also, if you are writing OOP, validation probably belongs on the domain entity that represents a transaction, rather than in a validation helper class.