Function get_permalink() not working properly in if statement (Wordpress)

Question

I am working on changing how posts in slider on this website ( https://otwartakultura.org/ ) are linked. Now they can link only to post, but I would like to have possibility to link to other pages.

I have created a new field in ACF ('link'). I wrote if statement - when the 'link' field is not empty, use 'link' value; else: use post permalink. It works for 'link" value, but for "else" it shows homepage url not post url.

Current working code:

 <article<?php
    if (has_post_thumbnail()) {
        ?> style="background-image: url('<?php echo  the_post_thumbnail_url('full'); ?>');"<?php
    } ?>>
<a href="<?php echo get_permalink() ?>">
<header>
<div class="title-box">
        <h1><?php echo get_the_title(); ?></h1>
    <span class="read-more">czytaj więcej ></span>
    </div></header></a>
</article> 

Code I have tried to use:

<article<?php
      if (has_post_thumbnail()) {
    ?> style="background-image: url('<?php echo the_post_thumbnail_url('full'); ?>');"<?php
    } ?>>

<a href="<?php
if (get_field( 'link' ) !==0) {
echo get_field( 'link' ); }
else {
echo get_the_permalink();
} ?>">

<header>
<div class="title-box">
        <h1><?php echo get_title(); ?></h1>
    <span class="read-more">czytaj więcej ></span>
    </div></header></a>
</article>

Please help:)

Answer 1

Above this:

<?php
    while ( have_posts() ) {
        the_post(); ?>
    <article <?php
        if (has_post_thumbnail()) {
            ?> style="background-image: url('<?php echo the_post_thumbnail_url('full'); ?>');"<?php
        } ?>>
    <a href="<?php echo get_permalink() ?>">
    <header>
    <div class="title-box">
            <h1><?php echo get_the_title(); ?></h1>
        <span class="read-more">czytaj więcej ></span>
        </div></header></a>
    </article>
        <?php
    } ?>

Paste this:

<article style="background-image: url('ADD_SOME_URL');">
    <a href="google.com">
    <header>
    <div class="title-box">
            <h1>Some title</h1>
        <span class="read-more">czytaj więcej ></span>
        </div></header></a>
        </article>

So all Together will look like this:

<?php
if ( have_posts() ) {
    ?><div id="promobox"><div id="news" class="cycle-slideshow"
        data-cycle-slides="> article"
        data-cycle-pager-template="<span></span>">
    <div class="cycle-pager"></div>


    <article style="background-image: url('ADD_SOME_URL');">
    <a href="google.com">
    <header>
    <div class="title-box">
            <h1>Some title</h1>
        <span class="read-more">czytaj więcej ></span>
        </div></header></a>
        </article>


    <?php
    while ( have_posts() ) {
        the_post(); ?>
    <article <?php
        if (has_post_thumbnail()) {
            ?> style="background-image: url('<?php echo the_post_thumbnail_url('full'); ?>');"<?php
        } ?>>
    <a href="<?php echo get_permalink() ?>">
    <header>
    <div class="title-box">
            <h1><?php echo get_the_title(); ?></h1>
        <span class="read-more">czytaj więcej ></span>
        </div></header></a>
    </article>
        <?php
    } ?>
    </div>
    <a id="archive" href="/archiwum/">archiwum aktualności</a>
    </div>
<?php
}
?>

Comment answer if some thing is not ok and edit hard coded article set background-image: url() and title in <h1> tag.