---
title: 'Custom Fields ● OpenStreetMap'
created_time: '2023-09-23 15:31:17'
language: fr
subtitle: ''
---

# Custom Fields ● OpenStreetMap

**with plenty of features**

by Marc Dechèvre

![Marc](%URL%.images/marc_dechevre.jpg "100x100")

present slides <i class="fa fa-desktop"></i>  https://slides.woluweb.be

## Goal of this presentation

The goal is to create and assign an OpenStreetMap Custom Field to one or several categories.
So each article (being Members, Events, whatever) will be geolocalized.

And based on this we will create a global OpenStreetMap module showing all the locations.

---

A side-goal of this presentation is also to introduce to **overrides** (or actually, **alternate layouts** meaning that I am not overriding the view in all cases but only where I want it).

Even if you are not a coder or a developer, you will see that Joomla makes it very easy to customize any **view**
(for example article view, blog view and -in this case- module view)

---

We will start with a simple multiple markers map.

And then we will even end up with:
- Multiple markers
- Different markers for each category
- Tooltip showing<br />1. Title with Link<br />2. Intro Image<br />3. Intro Text
- Clustering
- And even Layers with Filters

## NEW FOR JOOMLA 4

Someone contacted me in June 2023 to let me know that the override would not work any more (at least in her case) in Joomla 4 while it was working on her Joomla 3 website.

That error was mentioning "FieldsHelper".

So I just told her to add the following at the beginning of the file and this solved the issue:

`use Joomla\Component\Fields\Administrator\Helper\FieldsHelper`

## What we will achieve

![cf-osm](%URL%.images/cf-osm.gif)

## The online demo

https://joomlacustomfields.org/en/

## OpenStreetMap - Leaflet

In order to create our OpenStreetMap, we will use the following open-source Javascript library:
https://leafletjs.com/

See the following examples:
https://leafletjs.com/examples.html

Note : don't forget of course to add the link to the .js file and to the .css file

## OSM Custom Fields

I have found 3 OpenStreetMap Custom Fields out there.

Each has its strengths :)

### Advanced Custom Fields by Tassos Marinos

Free and Paid (€ 19)

Includes 25+ Custom Fields, among which OSM, Google Maps & Bing Maps

https://www.tassos.gr/joomla-extensions/advanced-custom-fields
https://www.tassos.gr/joomla-extensions/advanced-custom-fields/docs/the-openstreetmap-field

### OpenStreetMap Custom Field by Nordmograph

Paid (€ 10)

There is also a Google Maps field.
There are also extensions allowing to build maps linked to different sources (Articles but also third-party extensions.
You can really build crazy things

https://extensions.joomla.org/extensions/extension/authoring-a-content/custom-fields/openstreetmap-custom-field/

### OpenStreetMap by GMapFP

Free

There are also plenty of maps-related extensions by GMapFP.

https://creation-web.pro/extensions-joomla-francaises/46-field-osm

## The chosen OSM Custom Field

For the sake of this presentation we will use the OSM Custom Field, being part of Advanced Custom Fields by Tassos Marinos.

The reason being that it will only write the Latitude/Longitude in the database (without extra informations like a personalized marker, a text, a zoom level or whatever).

So it will be easier for us to manipulate this Custom Field to create our multiple markers map.

## Little change since version 1.1.0 of that OSM Custom Field

Since version 1.1.0 released in June 2020, this OSM Custom field by Tassos Marinos has new features and includes a.o. a Text field in order to display a Tooltip.

In practice this means that the value of the OSM field is now stored in the database as JSON, in both Free and Pro versions and regardless of whether you've any of the new options enabled. 

In practise this means that I have adapted slightly the code in the overrides shown in the next Chapter.

---

**Before**
```php
$latlon = $fields_by_name['open-street-map']->rawvalue;
```

and you would echo $latlon

**Now**
```php
$value = json_decode($fields_by_name['open-street-map']->rawvalue);
$tooltip = $value->tooltip;
$latlon = $value->coordinates;
```

and you would echo $latlon

Note : the tooltip is a Pro feature. We don't need it in our examples even if I mention it here for completeness

---

There are 3 scenarios (no matter whether you are using Free or Pro, activating the Tooltip or not) :

1. if you have upgraded from a previous version and already had articles having an OSM custom field and are ready to edit&save each concerned article then you should simply use the **code "after"**
2. if you have upgraded from a previous version and already had articles having an OSM custom field but are NOT ready to edit&save each concerned article (for example bc you have too many) then you have to add the **fixValue()** Method. See code on the next slide
3. if you are still on some previous version and don't want to update then you should use the **code "now"** or [better option] use the **fixValue()** Method to be future-proof

---

Note : actually if you have a mix of articles in the new and in the old format, the latter will simply not show on the map
- unless you edit&save them (scenario 1)
- or unless you add the fixValue() Method (scenario 2)

---

Code to be used if you keep articles having the old format:

```php
// this should be put outside the loop
// the OSM CF rawvalue will be transformed in the new format for articles having the old format
function fixValue(&$value) {
    // New format already
    if (is_object(json_decode($value)))
    {
       return;
    }

    // Convert old format
    $value = json_encode(['coordinates' => $value]);
}

// this will be put inside the loop (like in the classical example)
$value = $fields_by_name['open-street-map']->rawvalue;
fixValue($value);
$value = json_decode($value);
$latlon = $value->coordinates;
$tooltip = $value->tooltip;
```

## Your own map-marker

Instead of PNG image, I chose SVG image for two reasons :
1. vector => image is always perfect whatever its size
2. easy to edit to change colors : you don't need Photoshop... just edit it with your basic Text Editor

The present SVG was found on https://www.iconfinder.com/search/?q=map+marker&from=navbar

## Preparing the Articles

In the present demo, we will create two Categories
- JoomlaDays
- Joomla User Groups

Then we install the OSM Custom Field.

Finally, we create a OSM Custom Field and assign it to the 2 above categories.

## OSM with override

### Modules: Articles - Newsflash

As you remember from the previous presentations (or from the Joomla Community Magazine https://magazine.joomla.org/all-issues/april-2020/custom-fields-episode-4-a-step-by-step-tutorial), in an override / alternate layout we can display the Custom Field having ID "X" with the following line of code :
```php
<?php echo $this->item->jcfields[X]->value; ?>
```

This works automatically for many Views, but not for all of them.

---

For example, in **Modules: Articles - Newsflash**, if you set "Trigger Plugin Events" to YES, then the variable jcfields will be available.
But if you set it to NO, the Custom Fields won't be readily available.

And for this presentation I don't want to use **Modules: Articles - Newsflash** because it has too many options (so one might get confused by the length of the override).

### Modules: Articles - Latest News

Therefore, I prefer to use **Modules: Articles - Latest** because it has just the Options we need :
- Category: selection of one or multiple Category
- Count: set it to 0 to have no limit

The only drawback is that jcfields is not readily available.
Nevermind, Alexandre ELISÉ shared a few line of codes allowing to use Custom Fields by ID and even by Name in such a case:
https://gist.github.com/alexandreelise/e04d417c9f911ce2ab2a3e931142e89b

### Override print_r

if you want to see what is available for each Article

```php
<?php
/**
 * @package     Joomla.Site
 * @subpackage  mod_articles_latest
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;
?>

<?php 
foreach ($list as $item) {
    echo '<pre>' . print_r($item, true) . '</pre>';
}
?>
```

### adding CSS and JS in our override

Instead of adding the **Leaflet** CSS and JS directly like this

```php
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.6.0/dist/leaflet.css" integrity="sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==" crossorigin=""/>
<script src="https://unpkg.com/leaflet@1.6.0/dist/leaflet.js" integrity="sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==" crossorigin=""></script>
```

we should use Joomla's API for stylesheets/scripts and have this
```php
<?php
// https://docs.joomla.org/J3.x:Adding_JavaScript_and_CSS_to_the_page
use Joomla\CMS\Factory;
$document = Factory::getDocument();
$document->addStyleSheet("https://unpkg.com/leaflet@1.6.0/dist/leaflet.css", [], ['integrity' => 'sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==','crossorigin' => '']);
$document->addScript("https://unpkg.com/leaflet@1.6.0/dist/leaflet.js", [], ['integrity' => 'sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==','crossorigin' => '']);
?>
```

<small>Txs to Dimitris Grammatikogiannis for [drawing our attention to this](https://twitter.com/woluweb/status/1268164681883176962)</small>

### OSM with override - basic - screenshot

multiple Categories | tooltip with link to Article | standard Marker

![osmbasic](%URL%.images/osmbasic.png)

### OSM with override - basic - code

```php
<?php
/**
 * @package     Joomla.Site
 * @subpackage  mod_articles_latest
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;
?>

<?php
// https://docs.joomla.org/J3.x:Adding_JavaScript_and_CSS_to_the_page
use Joomla\CMS\Factory;
$document = Factory::getDocument();
$document->addStyleSheet("https://unpkg.com/leaflet@1.6.0/dist/leaflet.css", [], ['integrity' => 'sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==','crossorigin' => '']);
$document->addScript("https://unpkg.com/leaflet@1.6.0/dist/leaflet.js", [], ['integrity' => 'sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==','crossorigin' => '']);
?>

<h2>Override for OpenStreetMap</h2>

<div id="map" style="width: 100%; height: 400px;">&nbsp;</div>

<script>
	var map = L.map('map').setView([50.84717044999999,4.35198095255952], 6);

	L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
		attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
	}).addTo(map);

    <?php foreach ($list as $item) : ?>

      <?php
          // example made after an exchange between Marc Dechèvre and Alexandre Elisé
          // https://gist.github.com/alexandreelise/e04d417c9f911ce2ab2a3e931142e89b
          $jcfields = FieldsHelper::getFields('com_content.article', $item, true);
          // custom fields by name
          // usage: $fields_by_name['name-of-field']->value
          $fields_by_name = \Joomla\Utilities\ArrayHelper::pivot($jcfields, 'name');
      ?>

      <?php
		  $value = json_decode($fields_by_name['open-street-map']->rawvalue);
          $tooltip = $value->tooltip;
		  $latlon = $value->coordinates;
	  ?>

      <?php if (!empty($latlon)): // add a marker only if lat/long is not empty otherwise would get error ?>
		<?php // use htmlspecialchars($item->title ,ENT_QUOTES) for the Title and not just $item->title otherwise the map would not display if the Title would for example contain a simple quote ?>
		L.marker([<?php echo $latlon; ?>]).bindPopup('<a href="<?php echo $item->link; ?>"><?php echo htmlspecialchars($item->title, ENT_QUOTES); ?></a>').addTo(map);
	  <?php endif ?>

    <?php endforeach; ?>

</script>
```

### OSM with override - basic with clustering

When you have numerous locations then you will probably want to have clustering on your map so that map-markers "merge" when unzooming.

In order to do that, we need to integrate another javascript in our code.

Instead of adding the different points directly to the Map, we add them to a Layer. And once the Layer is complete we add it to the map. And all points on that Layer will *cluster* automatically when needed :)

### OSM with override - basic with clustering - code

```php
<?php
/**
 * @package     Joomla.Site
 * @subpackage  mod_articles_latest
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;
?>

<?php
// https://docs.joomla.org/J3.x:Adding_JavaScript_and_CSS_to_the_page
use Joomla\CMS\Factory;
$document = Factory::getDocument();

// Leaflet library - SEE : https://leafletjs.com/
$document->addStyleSheet("https://unpkg.com/leaflet@1.6.0/dist/leaflet.css", [], ['integrity' => 'sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==','crossorigin' => '']);
$document->addScript("https://unpkg.com/leaflet@1.6.0/dist/leaflet.js", [], ['integrity' => 'sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==','crossorigin' => '']);

// Cluster plugin - SEE : https://github.com/Leaflet/Leaflet.markercluster
$document->addStyleSheet("https://leaflet.github.io/Leaflet.markercluster/dist/MarkerCluster.css", [], ['crossorigin' => '']);
$document->addStyleSheet("https://leaflet.github.io/Leaflet.markercluster/dist/MarkerCluster.Default.css", [], ['crossorigin' => '']);
$document->addScript("https://leaflet.github.io/Leaflet.markercluster/dist/leaflet.markercluster-src.js", [], ['crossorigin' => '']);
?>

<h2>Override for OpenStreetMap</h2>

<div id="map" style="width: 100%; height: 400px;">&nbsp;</div>

<script>
    var map = L.map('map').setView([50.84717044999999,4.35198095255952], 6);

    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
    }).addTo(map);

    var myClusterGroup = L.markerClusterGroup();

    <?php foreach ($list as $item) : ?>

      <?php
          // example made after an exchange between Marc Dechèvre and Alexandre Elisé
          // https://gist.github.com/alexandreelise/e04d417c9f911ce2ab2a3e931142e89b
          $jcfields = FieldsHelper::getFields('com_content.article', $item, true);
          // custom fields by name
          // usage: $fields_by_name['name-of-field']->value
          $fields_by_name = \Joomla\Utilities\ArrayHelper::pivot($jcfields, 'name');
      ?>

      <?php
		  $value = json_decode($fields_by_name['open-street-map']->rawvalue);
          $tooltip = $value->tooltip;
		  $latlon = $value->coordinates;
	  ?>
	  
       <?php if (!empty($latlon)): // add a marker only if lat/long is not empty otherwise would get error ?>
       <?php // use htmlspecialchars($item->title ,ENT_QUOTES) for the Title and not just $item->title otherwise the map would not display if the Title would for example contain a simple quote ?>

		var marker = L.marker([<?php echo $latlon; ?>]).bindPopup('<a href="<?php echo $item->link; ?>"><?php echo htmlspecialchars($item->title, ENT_QUOTES); ?></a>');
		
		myClusterGroup.addLayer(marker);

       <?php endif ?>

    <?php endforeach; ?>

    map.addLayer(myClusterGroup);

</script>
```

### OSM with override - intermediate - screenshot

diff. Marker for each Category | tooltip with extra Custom Fields

![osmintermediate](%URL%.images/osmintermediate.png)

### OSM with override - intermediate - code

```php
<?php
/**
 * @package     Joomla.Site
 * @subpackage  mod_articles_latest
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;
?>

<?php
// https://docs.joomla.org/J3.x:Adding_JavaScript_and_CSS_to_the_page
use Joomla\CMS\Factory;
$document = Factory::getDocument();
$document->addStyleSheet("https://unpkg.com/leaflet@1.6.0/dist/leaflet.css", [], ['integrity' => 'sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==','crossorigin' => '']);
$document->addScript("https://unpkg.com/leaflet@1.6.0/dist/leaflet.js", [], ['integrity' => 'sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==','crossorigin' => '']);
?>

<h2>Override for OpenStreetMap</h2>

<div id="map" style="width: 100%; height: 400px;"></div>
<script>
	var map = L.map('map').setView([50.84717044999999,4.35198095255952], 6);

	L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
		attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
	}).addTo(map);

	var MyOwnIcon = L.Icon.extend({
		options: {
			iconSize: [40, 40],
			iconAnchor: [20, 40],
          	popupAnchor:  [0, -45]
		}
	});

	var jugsIcon = new MyOwnIcon({
			iconUrl: '/images/map-marker-blue.svg'
		}),
		joomladaysIcon = new MyOwnIcon({
			iconUrl: '/images/map-marker-green.svg'
        }),
		enIcon = new MyOwnIcon({
			iconUrl: '/images/map-marker-red.svg'
		});

    L.control.scale().addTo(map);

    <?php foreach ($list as $item) : ?>

      <?php
          // example made after an exchange between Marc Dechèvre and Alexandre Elisé
          // https://gist.github.com/alexandreelise/e04d417c9f911ce2ab2a3e931142e89b
          $jcfields = FieldsHelper::getFields('com_content.article', $item, true);
          // custom fields by name
          // usage: $fields_by_name['name-of-field']->value
          $fields_by_name = \Joomla\Utilities\ArrayHelper::pivot($jcfields, 'name');
      ?>

      <?php
		  $value = json_decode($fields_by_name['open-street-map']->rawvalue);
          $tooltip = $value->tooltip;
		  $latlon = $value->coordinates;
	  ?>
	  
       <?php if (!empty($latlon)): // add a marker only if lat/long is not empty otherwise would get error ?>
        <?php // use htmlspecialchars($item->title ,ENT_QUOTES) for the Title and not just $item->title otherwise the map would not display if the Title would for example contain a simple quote ?>


	var customPopup = '<a href="<?php echo $item->link; ?>"><?php echo htmlspecialchars($item->title, ENT_QUOTES); ?></a><br /><?php echo $fields_by_name['country']->value; ?>';
    	
      L.marker([<?php echo $latlon; ?>], {icon: <?php echo $item->category_alias; ?>Icon}).bindPopup(customPopup).addTo(map);
	<?php endif ?>

    <?php endforeach; ?>

</script>

```

### OSM with override - advanced - screenshot

Clustering | Layers with Filters

![osmadvanced](%URL%.images/osmadvanced.png)

### OSM with override - advanced - code
		
```php
<?php
/**
 * @package     Joomla.Site
 * @subpackage  mod_articles_latest
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;
?>

<?php
// https://docs.joomla.org/J3.x:Adding_JavaScript_and_CSS_to_the_page
use Joomla\CMS\Factory;
$document = Factory::getDocument();

// Leaflet library - SEE : https://leafletjs.com/
$document->addStyleSheet("https://unpkg.com/leaflet@1.6.0/dist/leaflet.css", [], ['integrity' => 'sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==','crossorigin' => '']);
$document->addScript("https://unpkg.com/leaflet@1.6.0/dist/leaflet.js", [], ['integrity' => 'sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==','crossorigin' => '']);

// Cluster plugin - SEE : https://github.com/Leaflet/Leaflet.markercluster
$document->addStyleSheet("https://leaflet.github.io/Leaflet.markercluster/dist/MarkerCluster.css", [], ['crossorigin' => '']);
$document->addStyleSheet("https://leaflet.github.io/Leaflet.markercluster/dist/MarkerCluster.Default.css", [], ['crossorigin' => '']);
$document->addScript("https://leaflet.github.io/Leaflet.markercluster/dist/leaflet.markercluster-src.js", [], ['crossorigin' => '']);
?>

<?php
use Joomla\CMS\Uri\Uri;

// A function used when we need to pass HTML code into a Javascript variable (article's title and introduction) 
function convertHtmlToJsString($string)
{
	$string = str_replace("\r", "", $string);
	$string = str_replace("\n", "", $string);
	return addslashes($string);
}
?>

<h2>Override for OpenStreetMap</h2>

<div id="map" style="width: 100%; height: 400px;"></div>
<script>
document.addEventListener('DOMContentLoaded', function() {
	// 
	var icon_dirname = '<?php echo Uri::root();?>/images';
	var map_center_latlon = [50.84717044999999,4.35198095255952];
	var map_zoom_initial = 6;
	var use_clustering = true; // true | false

	// Declare icons
	var MyOwnIcon = L.Icon.extend({
		options: {
			iconSize: [40, 40],
			iconAnchor: [20, 40],
			popupAnchor:  [0, -45]
		}
	});
	var jugsIcon = new MyOwnIcon({
		iconUrl: icon_dirname + '/map-marker-blue.svg'
	});
	var joomladaysIcon = new MyOwnIcon({
		iconUrl: icon_dirname + '/map-marker-green.svg'
	});
	//
	var map = L.map('map').setView(map_center_latlon, map_zoom_initial);
	L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
			attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
	}).addTo(map);
	L.control.scale().addTo(map);

	// Because we use "overlays" (checkbox markers selection) we need layergroups.
	// See : https://leafletjs.com/reference-1.6.0.html#control-layers
	var layerGroups = {};
	var layergroup_name;
<?php foreach ($list as $item) : ?>
<?php
	// example made after an exchange between Marc Dechèvre and Alexandre Elisé
	// https://gist.github.com/alexandreelise/e04d417c9f911ce2ab2a3e931142e89b
	$jcfields = FieldsHelper::getFields('com_content.article', $item, true);
	// custom fields by name
	// usage: $fields_by_name['name-of-field']->value
	$fields_by_name = \Joomla\Utilities\ArrayHelper::pivot($jcfields, 'name');

    $value = json_decode($fields_by_name['open-street-map']->rawvalue);
    $tooltip = $value->tooltip;
    $latlon = $value->coordinates;

	// Check if custom field "open-street-map" is filled (should add some more checks)
	if(isset($fields_by_name['open-street-map']) && trim($latlon) != ''){
?>
<?php $article_images  = json_decode($item->images); ?> 

	layergroup_name = '<?php echo $item->category_alias;?>';
	// Create a layergroup for the article's category (only once by category).
	if(layerGroups[layergroup_name] == undefined){
		if(use_clustering == true){
			layerGroups[layergroup_name] = L.markerClusterGroup();
		}else{
			layerGroups[layergroup_name] = L.layerGroup(); 
		}
	}
	// Add the marker into the layergroup
	var marker = L.marker([<?php echo $latlon; ?>], {icon: <?php echo $item->category_alias; ?>Icon});
	// Use htmlspecialchars($item->title ,ENT_QUOTES) for the Title and not just $item->title otherwise the map would not display if the Title would for example contain a simple quote.
	var title = <?php echo "'" . convertHtmlToJsString($item->title) . "'" ?>;
	var introduction = <?php echo "'" . convertHtmlToJsString($item->introtext) . "'" ?>;
	var introimage='';
	<?php if(!empty($article_images->image_intro)) 	echo "var introimage = '<img src=\"" . $article_images->image_intro ."\"style=\"width: 200px;\">'"	?>;
	
	marker.bindPopup('<a href="<?php echo $item->link; ?>">' + title + '</a>'+ introduction + introimage);
	layerGroups[layergroup_name].addLayer(marker);
<?php
	}else{
		// If custom field is not filled, add some debug comments
		echo "// " . $latlon . "\n";
		echo "// " . $item->title . "\n";
	}
?>
<?php endforeach; ?>
	// Add layergroups to the map
	
	for(var layergroup_name in layerGroups){
		layerGroups[layergroup_name].addTo(map);
	}
	// Add "overlays" (checkboxes for each category) to the map
	var baseLayers = {};
	var overlays = layerGroups;
	L.control.layers(baseLayers, overlays).addTo(map);
});
</script>
```

### OSM with different tiles

As you can see from the examples above, to have the "classic" **tiles** we just use the following

``` html
https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png
```

But we could use other sources of course.

For example if you want "black & white" **tiles**, just replace the above link by the following

``` html
https://tiles.wmflabs.org/bw-mapnik/{z}/{x}/{y}.png
```

You can find other source for example on https://wiki.openstreetmap.org/wiki/Tile_servers

## Thank you

For giving me the idea of this presentation and his example

*Philippe COMBET http://www.adosis.com*

For the trick to easily integrate Custom Fields in Overrides where it is not foreseen

*Alexandre ELISÉ https://alexandre-elise.fr*

For the Clustering and the Layers

*Philippe LAMBOTTE https://www.m4ucode.be*

 
---

For their Custom Fields and the new versions following our exchanges

*Tassos MARINOS https://www.tassos.gr*

*Adrien ROUSSEL https://www.nordmograph.com*

*Fabrice PELLETIER https://www.gmapfp.org*

---

For being #jPositive

*So many members of the Joomla Community ;)*

## Get in touch

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Any suggestion about this presentation ?<br />
Please feel free to contact me. I'll be happy to keep improving it:)

<i class="fa fa-user"></i> <i class="fa fa-facebook"></i> [Marc Dechèvre](https://www.facebook.com/marc.dechevre) | <i class="fa fa-skype" aria-hidden="true"></i> <i class="fa fa-twitter"></i> [woluweb](https://twitter.com/woluweb)<br />
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