Wordpress functions not working in custom theme - php

Question

So I'm super new to Wordpress. I set up a Wordpress local server on MAMP yesterday and I'm trying to build my own theme currently. Trouble is, whenever I try to do the loop, I'm not getting any content. my code works if I just use php, but the problem is custom Wordpress functions aren't usable (i.e. have_posts())
A couple other posts have suggested requiring wp-blog-header, but that hasn't worked either. Here's my code:
<?php
define('WP_USE_THEMES', false);
require('../../../wp-blog-header.php');
if(have_posts()) :
echo 'testing'
else :
echo 'testing'
endif;
?>
Nothing currently displays on my screen.
wp-blog-header.php is located here: wordpress -> wp-blog-header.php
My custom theme is located here: wordpress -> wp-content -> themes -> firstTheme -> index.php
All tips are appreciated.

Answer 1

Well, you're writing PHP and your code contains
if(have_posts()) :
echo 'testing'
else :
echo 'testing'
endif;
I'm not sure how can this be valid in PHP. I'd expect
if(have_posts())
echo 'testing';
else
echo 'testing';
See also if and else syntax in PHP.

Answer 2

I found this issue as well in building a few wordpress sites. After installing a PhP plugin (Insert PhP) my problems were solved.
Once installed, was changed to [insert_php] and [/insert_php] and my code worked.

Answer 3

You need to use the proper WordPress functions to build your own custom theme.
For example, instead of require and then x-path deep (which is also not wanted from WP-Core perspective) you should put your file in your theme's root.
like :
`get_template_part('name-of-file-to-include-without-php-ending');`
Reason for this is the fact, that WordPress Codex proposes the use of child theme functions.
The get_template_part(''); function does some checks, e.g. if a child theme has been installed etc.
Question: Why do you define that constant?
All constants should reside inside wp-config (root folder).
Additionally, it is worth mentioning that you are not looping throught the posts. Your code, at this point in time of writing, only looks IF there are posts, and then does nothing. You need to add the while function as well in order to work through your posts and display them.
So, do (in your loop.php or at the place in your theme where you want to display them):
<?php if(have_posts() ) : ?>
// The while added
<?php while ( have_posts() ) : the_post(); ?>
// Your template tags here: e.g. the_author();
<h2><?php the_author(); ?></h2>
<h3>the_title();</h3>
etc...
<?php endwhile?>
<?php endif; ?>
One last thing: WordPress has some conventions, which files should reside in the theme folder. For example, every theme should have a functions.php where you put stuff like menu and widgets etc. inside.
The most popular tags to build a theme are:
get_header();
Sure, you need to have a header.php file in your theme. Again, WordPress will look for exactly these files to include, no other naming is allowed.
get_footer();
Make a guess, right - it will look for footer.php in your theme folder.
For more information please see the WordPress Codex > Template Parts, etc..
https://codex.wordpress.org/Theme_Development#Template_Files
I highly advice you to use the WordPress core functions for templates, ignoring them and do 'classic' php e.g. include/require will lead you the dark side and not be successful.
A good plugin in the see your which template parts you are using is "What the File". Grab a default theme, install that plugin and look in the admin bar what it says to get an idea of what WordPress is doing.
Here is an excerpt of my loop, in my theme which uses bootstrap.
<?php if(have_posts() ) : ?>
<?php while ( have_posts() ) : the_post(); ?>
<?php if(is_front_page() || is_page() || is_single() ) : ?>
<div class="row row-content">
<div class="content col-xs-12 col-sm-12 col-md-12 col-lg-12">
<?php the_content(); ?>
</div>
</div>
<?php // category.php, archive.php, search.php ?>
<?php elseif(is_category() || is_archive() || is_search() ) : ?>
<div class="row row-excerpt">
<div class="thumbnail-box col-lg-4">
<a href="<?php the_permalink(); ?>" class="preview-image-link">
<?php
// Thumbnail und Post Auszug
if(has_post_thumbnail() ) {
the_post_thumbnail('thumbnail');
}
?>
</a>
</div>
<div class="text-details-box col-lg-8">
<div class="row row-excerpt-text">
<div class="excerpt col-lg-12">
<?php the_excerpt(); ?>
</div>
</div>
<div class="row row-tags row-read-more">
<div class="tags col-lg-8">
<?php the_tags('<ul class="tag-list">
</div>
<div class="read-more-boxcol-md-4 col-lg-4">
<a href="<?php the_permalink(); ?>" class="read-more-btn">
<span class="read-more-btn-text">></span>
</a>
</div>
</div>
</div>
</div>
<?php endwhile; ?>
<?php endif; ?>