Getting invalid argument for foreach error when using an array

Question

I can not understand why this error is occurring. From what I can see I the function I use correctly returns an array of data that exists on the database. I use a foreach() to echo out each of the data in the array but it gives me the error: Warning: Invalid argument supplied for foreach().

Here is the function:

// Retrieve posts
    function retrieve_posts(){
        // start new instance of the database connection 
        global $dbh;

        // Get all the posts
        $stmt = $dbh->prepare("SELECT * FROM jacks_barbers_reviews ORDER BY date DESC");
        $stmt->execute();

        while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {

                $result[] = $row;
        }

        return $result;
    }

And the (simplified) foreach loop:

<?php

        $posts = retrieve_posts();


            foreach($posts AS $index){

                echo '<div class="test-wrap">'; //contains the individual testimonials
                echo '<p>' . $index['post'] . '</p>';
                echo '<p style="float:right;font-style:normal;font-size:15px;">By ' .$index['name']. '  ' .$index['date']. '</p>';
                echo '<div style="clear:both"></div>';
                echo '</div>'; // closes test-wrap
            }


    ?>

So what is causing this error?

Thanks

If no posts are retrieved by your SQL query, then you'll be a null return from the function because $result is undefined.... define it as an empty array before your while loop in retrieve_posts() — Mark Baker
– Mark Baker, Commented Jun 18, 2013 at 20:37
How about doing return $stmt->fetchAll() to get all the rows? I cannot se anything wrong with the foreach as long as post and name really are columns of jacks_barbers_reviews. Consider not using *. — Sylwester
– Sylwester, Commented Jun 18, 2013 at 20:55

ducin · Accepted Answer · 2013-06-18 20:36:03Z

6

I guess this might happen if you have no results. You didn't initialize the $result variable in the retrieve_posts function. Null is returned and this is not an allowed value to be iterated inside foreach loop.

Try initializing the variable: $result = array(); before the while loop.

edit: Take a look at foreach official PHP docs:

The foreach construct provides an easy way to iterate over arrays. foreach works only on arrays and objects

If you haven't initialized it, you return a null value which is neither an object nor an array.

answered Jun 18, 2013 at 20:36

ducin

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4 Comments

crmepham Over a year ago

That'll teach me for not bothering to initialise my arrays before using them. Thanks.

ducin Over a year ago

@crm: this is a major weakness of PHP comparing to python. If you wrote something strange (or even completely wrong), PHP interpreter will often try to figure out what you meant. And this leads to such situations.

crmepham Over a year ago

@Pinoniq That doesn't seem to retrieve the results. Where as fetch(PDO::FETCH_ASSOC) does, I think it's a weird PHP thing?

ducin Over a year ago

BTW, try to avoid using global. This is a very ugly approach and many people will likely blame you for using it.

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