Foreach argument problem

Question

1.00/5 (1 vote)

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read.php

PHP

<?php
require_once('../dao/config.php');
require_once('../dao/crudDAO.php');

$list = crudDAO::read();
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">


<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CRUD



	<div>
    	<div>
        	
            	                	<?php foreach($list as $key => $value) { ?>
                    
                                        <?php } ?>
            <table><tbody><tr>                	<td>id</td>                    <td>Name</td>                    <td>Email</td>                    <td>Address</td>                    <td>Mobile number</td>                </tr><tr><td><?= $value['id'] ?></td>                    <td><?= $value['name'] ?></td>                    <td><?= $value['email'] ?></td>                    <td><?= $value['address'] ?></td>                    <td><?= $value['mob'] ?></td>                </tr></tbody></table>
        </div>
    </div>

error:
Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\crud_php\oop_crud\pages\read.php on line 25
id Name Email Address Mobile number

crudDAO.php

PHP

<?php
class CrudDAO {
	public function create($name, $email, $address, $mob) {
		global $db;
		$sql = "INSERT INTO users SET name = '$name', email = '$email', address = '$address', mob = '$mob'";
		$result = $db->query($sql);
		
		if($result) {
			return $result;
		} else {
			return false;
		}
	}
	
	public function read() {
		global $db;
		$sql = "SELECT * FROM users ORDER BY id";
		$result = $db->query($sql);
		
		if($result->num_rows > 0) {
			$i = 0;
			$list = " ";
			while($row = $result->fetch_assoc()) {
				$list[$i] = $row;
				$i++;
			}
			return $list;
		} else {
			return false;
		}
	}
	
	public function update() {
		global $db;
	}
	
	public function delete() {
		global $db;
	}
}
?>

error:
Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

What I have tried:

Find solution on internet

Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\crud_php\oop_crud\pages\read.php on line 25
id Name Email Address Mobile number

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

Posted 3-Apr-18 18:34pm

Member 13761429

Updated 3-Apr-18 21:35pm

PIEBALDconsult

v2

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2 solutions

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Jochen Arndt · Accepted Answer · 2018-04-03T21:37:00

Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\crud_php\oop_crud\pages\read.php on line 25

is issued for

PHP

<?php foreach($list as $key => $value) { ?>

The $list argument is invalid. PHP: foreach - Manual[^] expects an array expression.

It is assigned here

PHP

$list = crudDAO::read();

So the next step would be inspecting that function.

PHP

if($result->num_rows > 0) {
    $i = 0;
    $list = " ";
    while($row = $result->fetch_assoc()) {
        $list[$i] = $row;
        $i++;
    }
    return $list;
} else {
    return false;

It has two return paths. If not matching recordsets can be found the boolean value false is returned. So you have to check for that return value when calling the function or return an empty array instead of a boolean.

There are also the other warnings

Notice: Array to string conversion in C:\xampp\htdocs\crud_php\oop_crud\dao\crudDAO.php on line 24

They inform you that $list is an array of strings. But you want an array of an array. The solution is to declare $list as array. Putting it together you may use something like

PHP

$list = array();
if($result->num_rows > 0) {
    $i = 0;
    while($row = $result->fetch_assoc()) {
        $list[$i] = $row;
        $i++;
    }
}
return $list;
}

Patrice T · Accepted Answer · 2018-04-03T18:58:00

Even without any error, I fear this is an empty loop:

PHP

<?php foreach($list as $key => $value) { ?>
<?php } ?>

PHP

$sql = "INSERT INTO users SET name = '$name', email = '$email', address = '$address', mob = '$mob'";

Not a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
SQL Injection Prevention Cheat Sheet - OWASP[^]

Foreach argument problem

2 solutions

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