Wordpress shortcode php array to text in a text block - php

Question

I am beginning to make a site in wordpress (so no php or html experience). I want to generate textlist from a mysql column into a text block.
I have made the php code for the shortcode below which returns an array which now displays in the textblock as "Array" instead of a list of strings.
If i just print the values they appear on the head of the page.
What are the next steps I need to do/look for. I can't find it because I probably do not know the correct search terms. My guess is something with HTML.
<?php
function location_marker_shortcode( $atts ) {
$a = shortcode_atts( array(
'mapnumber' => 'world'
), $atts );
global $wpdb;
//select databases (the 84 part should be the input of the shortcode)
$marker_labels = $wpdb->get_col('SELECT label FROM wp_mapsvg_database_84');
foreach ( $marker_labels as $marker_label )
{
//print labels
echo $marker_label;
}
return $marker_labels;
}
//add shortcode to wordpress
add_shortcode( 'matthijs', 'location_marker_shortcode' );
?>
I have now this code which gives me a list exactly what i want but not in the "paragraph block" in wordpress where my shortcode is situated.
<?php
function location_marker_shortcode( $atts ) {
$a = shortcode_atts( array(
'mapnumber' => 'world'
), $atts );
global $wpdb;
//select databases (the 84 part should be the input of the shortcode)
$marker_labels = $wpdb->get_col('SELECT label FROM wp_mapsvg_database_84');
foreach ( $marker_labels as $marker_label )
{
echo '<li>'. $marker_label.'</li>';
}
}
//add shortcode to wordpress
add_shortcode( 'matthijs', 'location_marker_shortcode' );
?>

Answer 1

I'm not 100% sure what you're trying to accomplish, but try this. You don't want to echo out all the values as you're looping through them. Concatenate everything in a variable and then return the entire string at the end of your shortcode. This should generate an unordered list.
<?php
function location_marker_shortcode( $atts ) {
$a = shortcode_atts( array(
'mapnumber' => 'world'
), $atts );
global $wpdb;
//select databases (the 84 part should be the input of the shortcode)
$marker_labels = $wpdb->get_col('SELECT label FROM wp_mapsvg_database_84');
$output = '<ul>';
foreach ( $marker_labels as $marker_label )
{
$output .= '<li>' . $marker_label . '</li>';
}
$output .= '</ul>';
return $ouput;
}
//add shortcode to wordpress
add_shortcode( 'matthijs', 'location_marker_shortcode' );
?>