$wpdb->get_results() into foreach() returns always the word "Array" on top of the list . How to get rid of?

Question

I'm extracting field content forma a simple table under WordPress. The table contains the fields as in the screenshot here below and I need to extract all the values in rul_value for the row in which the field rul_type is "role"

So, I've made this query

$rows = $wpdb->get_results($wpdb->prepare("SELECT `rul_value` FROM " . _ROLES_  . " WHERE `rul_type` = %s AND `rul_value` LIKE %s", 'role', '%intera%'));
foreach($rows as $row) {
        $singleParts .= $row->rul_value . "\n";
}

but when printing it with

echo $singleParts;

or with

print_r($singleParts);

I get the list but the first word is "Array". Always. Actually it's not any array ... just this word appears. Which is very annoying

Here the output with var_dump($singleParts)

How can I get rid of? I have not clue why it's occurring this. Where am I wrong?

Answer 1

I'm not sure why you are getting errors but I can show you haw to defensively find and react to them.

This is your code

$rows = $wpdb->get_results($wpdb->prepare("SELECT `rul_value` FROM " . _ROLES_  . " WHERE `rul_type` = %s AND `rul_value` LIKE %s", 'role', '%intera%'));
foreach($rows as $row) {
    $singleParts .= $row->rul_value . "\n";
}

Let's make some changes.

Do you have data inside $singleParts already? If not, we can force it to be a clean empty var with $singleParts = '';.

Like this:

$rows = $wpdb->get_results($wpdb->prepare("SELECT `rul_value` FROM " . _ROLES_  . " WHERE `rul_type` = %s AND `rul_value` LIKE %s", 'role', '%intera%'));
$singleParts = '';
foreach($rows as $row) {
    $singleParts .= $row->rul_value . "\n";
}

Now we can cross that off the list of things going wrong. Next, you should inspect for an error. (Care of this answer)

if($wpdb->last_error !== ''){
    echo 'Opps something went wrong: ';

    $str   = htmlspecialchars( $wpdb->last_result, ENT_QUOTES );
    $query = htmlspecialchars( $wpdb->last_query, ENT_QUOTES );

    print "<div id='error'>
    <p class='wpdberror'><strong>WordPress database error:</strong> [$str]<br />
    <code>$query</code></p>
    </div>";
}else{
    # your code
}

Finally we can inspect the data you got back. We expected a string so we should make sure we got a string:

if(is_string($row->rul_value)){
    # your code
}else{
    echo "I was not expecting this. We got: <pre>";
    print_r($row->rul_value);
    echo "</pre>";
}

putting it al together we have:

$rows = $wpdb->get_results($wpdb->prepare("SELECT `rul_value` FROM " . _ROLES_  . " WHERE `rul_type` = %s AND `rul_value` LIKE %s", 'role', '%intera%'));
$singleParts = '';
if($wpdb->last_error !== ''){
    echo 'Opps something went wrong: ';

    $str   = htmlspecialchars( $wpdb->last_result, ENT_QUOTES );
    $query = htmlspecialchars( $wpdb->last_query, ENT_QUOTES );

    print "<div id='error'>
    <p class='wpdberror'><strong>WordPress database error:</strong> [$str]<br />
    <code>$query</code></p>
    </div>";
}else{
    # no wpdb error
    foreach($rows as $row) {
        if(is_string($row->rul_value)){
            # it is the string we were looking for
            $singleParts .= $row->rul_value . "\n";
        }else{
            # not a string - what did we get?
            echo "I was not expecting this. We got: <pre>";
            print_r($row->rul_value);
            echo "</pre>";
        }   
    }
}

Just echoing out possibly senstive data is not a great idea in production but for your development, this will help you trace where the errors are coming from. I recommend always assuming your data is mangled and checking it before doing things with it. Code is dumb and will do exactly what it was told regardless of our intentions.