Member Avatar for mexabet

I'm trying to automatically populate a navigation menu based on available categories in the database. As follows is my code:

<?php

    $sidenav = query("SELECT cat_id, cat_name FROM prod_cat ORDER By cat_name LIMIT 20");



    if ($sidenav != false)

    {

        $sidenav->execute();

        while($result = $sidenav->fetch(PDO::FETCH_BOTH))

        {

            echo "<div class='left_button'><a href='/customcms/products/index.php?page=list-product&category={$result['cat_id']}'>{$result['cat_name']}</a></div>";



        }

    }



?>

However, the code "$sidenav->execute();" gives the following error message: "Fatal error: Call to a member function execute() on a non-object on line ...".

Note: Please, be advised that "query" is a custom function and I'm connecting to the database via PDO.

Your help would be much appreciated, as always.

Edited by mexabet
  • 3 Contributors
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Dani AI

Generated

Short answer: the fatal error happened because your query() helper returned an array (or false), not a PDO statement object — so calling ->execute() on it fails. spotted this and was right that returning the statement would let you call execute()/fetch(); fixed the immediate problem correctly by iterating the returned array.

Two sensible designs for a DB helper:

  • Convenience mode: have the helper execute the statement and return rows (an array). Simple for small result sets (like a navigation list).
  • Low-level mode: have the helper return the PDOStatement so callers can stream rows (fetch one-by-one) or call execute() themselves. This is better for large result sets or when you need more control.

Quick, practical checks and a safe calling pattern

$rows = query($sql); // your helper

if ($rows === false) {
  // handle DB error
} elseif (is_array($rows)) {
  foreach ($rows as $row) {
    // safe output: escape values for HTML
    echo '<a href="?category='.rawurlencode($row['cat_id']).'">'.htmlspecialchars($row['cat_name']).'</a>';
  }
} elseif ($rows instanceof PDOStatement) {
  while ($row = $rows->fetch(PDO::FETCH_ASSOC)) {
    // same output
  }
}

Additional tips

  • In your helper, enable exceptions and a sensible default fetch mode: set PDO::ATTR_ERRMODE to PDO::ERRMODE_EXCEPTION and PDO::ATTR_DEFAULT_FETCH_MODE to PDO::FETCH_ASSOC.
  • Consider adding an optional flag to return the statement (e.g., $returnStatement = false), or create two helpers (fetchAll vs prepareStmt).
  • Always escape output (htmlspecialchars / rawurlencode) and prefer prepared statements for user-supplied values.

Recommended Answers

All 5 Replies

Member Avatar for pritaeas

Apparently your custom function returns null instead of a PDO statement object instance.

Member Avatar for mexabet

Thanks for the insight. See what I have in my functions.php for the query() function:

 function query(/* $sql [, ... ] */)

    {

        // SQL statement

        $sql = func_get_arg(0);



        // parameters, if any

        $parameters = array_slice(func_get_args(), 1);



        // try to connect to database

        static $handle;

        if (!isset($handle))

        {

            try

            {

                // connect to database

                $handle = new PDO("mysql:dbname=" . DB_NAME . ";host=" . DB_SERVER, DB_USERNAME, DB_PASSWORD);



                // ensure that PDO::prepare returns false when passed invalid SQL

                $handle->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); 

            }

            catch (Exception $e)

            {

                // trigger (big, orange) error

                trigger_error($e->getMessage(), E_USER_ERROR);

                exit;

            }

        }



        // prepare SQL statement

        $statement = $handle->prepare($sql);

        if ($statement === false)

        {

            // trigger (big, orange) error

            trigger_error($handle->errorInfo()[2], E_USER_ERROR);

            exit;

        }



        // execute SQL statement

        $results = $statement->execute($parameters);



        // return result set's rows, if any

        if ($results !== false)

        {

            return $statement->fetchAll(PDO::FETCH_ASSOC);

        }

        else

        {

            return false;

        }

    }

Please, how do I modify the above query() function to return the desired values?

Member Avatar for pritaeas

Line 87, your fetchAll, returns an array (assuming your query does not fail). You cannot execute fetch on an array, only on a PDO statement. So either return $statement in your method, or change your while loop into a foreach.

commented: Nice insight! +3
Member Avatar for jstfsklh211

your function doesn't return a statement it returns the result

$statement = $handle->prepare($sql);

you would need to return $statement for what you're attempting

commented: Good point! +3
Member Avatar for mexabet

, I was able to fix the issue by following your suggestion - changing the while loop to foreach. Thanks a lot.

, lots of thanks for your insight. I'll keep that in mind, as I learn.

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