Why Am I Getting a 'Trying to Get Property of Non-Object' Error in My PHP Code?

Troubleshooting "Trying to Get Property of Non-Object" Errors

When encountering the error message "Trying to get property of non-object," it's essential to examine the context of its occurrence. Let's delve into a specific case to understand the cause and resolution.

Problem Statement

In a PHP script, a query retrieves data from a database, but when attempting to access specific properties of the retrieved result, the error arises. The code snippets involved are as follows:

Control Page

include 'pages/db.php';
$results = mysql_query("SELECT * FROM sidemenu WHERE `menu_id`='".$menu."' ORDER BY `id` ASC LIMIT 1", $con);
$sidemenus = mysql_fetch_object($results);

View Page

foreach ($sidemenus as $sidemenu):
  echo $sidemenu->mname."<br />";
endforeach;

Cause Analysis

The root cause lies in the assumption that mysql_fetch_object() returns an array of objects, whereas in reality it retrieves only a single object. When iterating over the result in the view page, it attempts to access properties of an array element, which in this case is not an array but rather a singular object.

Resolution

To resolve the issue, a suitable modification to the script is required. One possible solution is to convert the result into an array of objects using a loop:

$results = mysql_query("SELECT * FROM sidemenu WHERE `menu_id`='".$menu."' ORDER BY `id` ASC LIMIT 1", $con);

$sidemenus = array();
while ($sidemenu = mysql_fetch_object($results)) {
    $sidemenus[] = $sidemenu;
}

By iterating over the result using a while loop, each object can be added to the $sidemenus array, creating an array that can be accessed as expected in the view page.

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