query - add_query_arg() and empty variables inside

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I have link:

<a href="'.esc_url(add_query_arg(array('search' => $search, 'category' => $category, 'filter' => $filter), '/site')).'">Click</a>

And some variables sometimes exist and sometimes don't, like $filter, which sometimes does not exist. Now I would like the variable does not exist, that it would not appear in the link, because the debugger displays the Notice "Undefined variable".

How should it be coded correctly?

I have link:

<a href="'.esc_url(add_query_arg(array('search' => $search, 'category' => $category, 'filter' => $filter), '/site')).'">Click</a>

And some variables sometimes exist and sometimes don't, like $filter, which sometimes does not exist. Now I would like the variable does not exist, that it would not appear in the link, because the debugger displays the Notice "Undefined variable".

How should it be coded correctly?

• query
• links

Share Improve this question asked Aug 26, 2019 at 14:04 manandmanmanandman 3522 bronze badges

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1 Answer 1

Sorted by: Reset to default 1

You can instantiate your array before-hand, optionally populate it, and pass it to the add_query_arg() function like so:

$url_query_args = array();

if( isset( $search ) ) {
    $url_query_args['search'] = $search;
}

if( isset( $category ) ) {
    $url_query_args['category'] = $category;
}

if( isset( $filter ) ) {
    $url_query_args['filter'] = $filter;
}

esc_url( add_query_arg( $url_query_args, '/site' ) );

Or you could loop through an array of possible query args:

$url_query_args = array();
$possible_args  = array(
    'search',
    'category',
    'filter',
);

foreach( $possible_args as $arg ) {

    if( ! isset( ${$arg} ) ) {
        continue;
    }

    $url_query_args[ $arg ] = ${$arg};

}

esc_url( add_query_arg( $url_query_args, '/site' ) );

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