User meta query results in PHP notice: only variables should be passed by reference

I am using a URL rewrite to put the user's display name in the URL to display a user profile. This part all works fine and the proper value is passed through the query_vars and I can get the correct user.

Since this is for a plugin, some plugin users may want to use the user's first/last name instead of the display name. I've set up an opportunity for them to do that where the first/last name is separated by an underscore(_).

To retrieve the user when the URL rewrite is passing the query_var "display_name", I am using a meta query in get_users().

// Get the custom query_var value.
$query_var = get_query_var( 'display_name' );

/**
 * When the display_name query_var is first name/last name,
 * (for example "john_smith"), split the value by unscore 
 * to get the individual first and last name values.
 */
$pieces = explode( '_', $query_var );

// User meta query to get the user ID by first_name/last_name.
$user = reset( get_users( array(
    'meta_query'  => array(
        'relation' => 'AND',
        array(
            'key'=>'first_name',
            'value' => $pieces[0],
            'compare' => '='
        ),
        array(
            'key' => 'last_name',
            'value' => $pieces[1],
            'compare' => '='
        )
    ),
    'number' => 1,
    'count_total' => false
) ) );

The meta query works fine and the correct user ID is returned, but I get a PHP notice as follows:

Notice: Only variables should be passed by reference

The line indicated is the meta query line $user = reset( get_users( array(

Any thoughts on what is wrong and is throwing the PHP notice? Any ideas on a better query to get the user ID by first name/last name meta keys?

I am using a URL rewrite to put the user's display name in the URL to display a user profile. This part all works fine and the proper value is passed through the query_vars and I can get the correct user.

Since this is for a plugin, some plugin users may want to use the user's first/last name instead of the display name. I've set up an opportunity for them to do that where the first/last name is separated by an underscore(_).

To retrieve the user when the URL rewrite is passing the query_var "display_name", I am using a meta query in get_users().

// Get the custom query_var value.
$query_var = get_query_var( 'display_name' );

/**
 * When the display_name query_var is first name/last name,
 * (for example "john_smith"), split the value by unscore 
 * to get the individual first and last name values.
 */
$pieces = explode( '_', $query_var );

// User meta query to get the user ID by first_name/last_name.
$user = reset( get_users( array(
    'meta_query'  => array(
        'relation' => 'AND',
        array(
            'key'=>'first_name',
            'value' => $pieces[0],
            'compare' => '='
        ),
        array(
            'key' => 'last_name',
            'value' => $pieces[1],
            'compare' => '='
        )
    ),
    'number' => 1,
    'count_total' => false
) ) );

The meta query works fine and the correct user ID is returned, but I get a PHP notice as follows:

Notice: Only variables should be passed by reference

The line indicated is the meta query line $user = reset( get_users( array(

Any thoughts on what is wrong and is throwing the PHP notice? Any ideas on a better query to get the user ID by first name/last name meta keys?

• meta-query
• users

Share Improve this question asked Dec 7, 2018 at 14:39 butlerblogbutlerblog 5,14133 gold badges2828 silver badges4444 bronze badges

Add a comment  | 

2 Answers 2

Sorted by: Reset to default 2

The value passed to reset() is passed by reference, which means technically it modifies the original variable that's passed to it. For this to work you need to pass a variable, not a function that returns a value.

reset() rewinds array's internal pointer to the first element and returns the value of the first array element.

All you need to do is assign the returned value if get_users() to a variable and then use reset() on that:

$users = get_users( array(
    'meta_query'  => array(
        'relation' => 'AND',
        array(
            'key'=>'first_name',
            'value' => $pieces[0],
            'compare' => '='
        ),
        array(
            'key' => 'last_name',
            'value' => $pieces[1],
            'compare' => '='
        )
    ),
    'number' => 1,
    'count_total' => false
) );

$user = reset( $users );

$user = reset( get_users( array(

The function reset() changes the passed variable, hence it needs a reference. Function output of get_users() can't be referenced because it is not a variable. Just assign the return value to a variable and call that:

$users = get_users( array(
    //...
) );
$user = reset( $users );