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27.

Block Plugins

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Well look at us! We've made it to the last topic of the tutorial. We've already transformed our static site into one where we can reorder the layout for each page, mix it with custom code from Twig templates and add dynamic content. That's... kind of awesome. Of course, we haven't covered everything you can do with Layouts, but you're now truly dangerous.

Creating a Custom Block?

One topic that we haven't covered is how to create a totally new block, but this is documented and, at this point, I think it wouldn't be too hard. Why would you build a custom block? Suppose you have something super custom like our "Hero" area or this "subscribe to newsletter" area, which is actually powered by Symfony's UX Live Component package, which gives it the fancy Ajax behavior.

Anyways, if you want something like this on your page, the simplest way to add it is... how I did in this project: put the logic in Symfony, render inside a Twig block, then include that Twig block inside of Layouts.

But what if we want the admin user to be able to add this to multiple pages whenever they want? That is when creating a custom block would be useful. Custom blocks can also have options, so you could even let them customize this in some way.

Hello Block Plugins

Anyways, let's do one last challenge related to blocks: create a block plugin. Go to a skill show page. Hmm, we could probably use a bit more margin between these blocks. And that's a pretty common need. We could handle this by adding a CSS class that sets the margin. But I want to make it even easier.

Go to the Layouts admin, then edit the Individual Skill Layout. Ok, suppose we want to add some margin right here. To do that, I want the admin user to be able to click on any block in the system - for example, this column block - and over on the design tab, select the top or bottom margin they need from a new form field.

This is a pretty wild goal... because, to accomplish it, we need to be able to modify every block in the system! Fortunately, that is exactly the point of a block plugin: to extend one - or every - block.

Creating the Block Plugin

Let's get to work. In the src/Layouts/ directory, create a new PHP class called, how about, VerticalWhitespacePlugin. This needs to implement a PluginInterface. But in practice, we extend a Plugin class that implements that interface for us. Go to "Code"->"Generate", or Command+N on a Mac, and implement the one method we need: getExtendedHandlers():

14 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 2
namespace App\Layouts;
use Netgen\Layouts\Block\BlockDefinition\Handler\Plugin;
class VerticalWhitespacePlugin extends Plugin
{
public static function getExtendedHandlers(): iterable
{
// TODO: Implement getExtendedHandlers() method.
}
}

Ok, each block in the system - so every item over here on the left menu - has a class behind it called a block handler. Our job in getExtendedHandlers() is to return an iterable of all the "handlers" that we want to extend. For example, if you wanted to only extend the title block, you could yield TitleHandler::class. How did I know to use that class? Well, most of the time you can guess: the title block has a TitleHandler. But if you want to look deeper, you can see all the handlers in the system by running:

php bin/console debug:container --tag=netgen_layouts.block_definition_handler

Anyways, in our case, we want to override every block. So we can yield BlockHandlerDefinitionInterface::class, because every block handler must implement that interface:

15 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 4
use Netgen\Layouts\Block\BlockDefinition\BlockDefinitionHandlerInterface;
// ... lines 6 - 7
class VerticalWhitespacePlugin extends Plugin
{
public static function getExtendedHandlers(): iterable
{
yield BlockDefinitionHandlerInterface::class;
}
}

And yes, I totally just forgot the word Definition. Whoops! I'll fix this bad interface in a minute.

Adding a Custom Block Parameter/Field

To see what to do next, go back to the "Code"->"Generate" menu, select "Override methods" and choose buildParameters(). We don't need to call the parent method because it's empty:

30 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 6
use Netgen\Layouts\Parameters\ParameterBuilderInterface;
// ... lines 8 - 9
class VerticalWhitespacePlugin extends Plugin
{
// ... lines 12 - 16
public function buildParameters(ParameterBuilderInterface $builder): void
{
// ... lines 19 - 27
}
}

Parameter is the word that Layouts uses for the form options that you can customize on the right side of the screen for every block. Thanks to our getExtendedHandlers() method, when Layouts builds those options for any block, it will now call this method and we can add new parameters.

I'll paste in the first... and we also need a use statement for this ParameterType namespace:

30 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 7
use Netgen\Layouts\Parameters\ParameterType;
class VerticalWhitespacePlugin extends Plugin
{
// ... lines 12 - 16
public function buildParameters(ParameterBuilderInterface $builder): void
{
$builder->add(
'vertical_whitespace:enabled',
ParameterType\Compound\BooleanType::class,
[
'default_value' => false,
'label' => 'Enable Vertical Whitespace?',
'groups' => [self::GROUP_DESIGN],
],
);
}
}

Cool! As you can see, Layouts comes with a bunch of built-in "field types" - like BooleanField, which will render as a checkbox. It defaults to false and has a label. Oh, and this group? Remember how there are two tabs - "Design" and "Content"? This is where you determine which your parameter should live inside.

And the first key - vertical_whitespace:enabled is the internal name of this field. You'll see how we use that in a minute.

Before we try this, future Ryan has just informed me that... I messed up! Typical. Scroll up. I'm yielding the wrong class! Yield BlockDefinitionHandlerInterface::class:

30 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 4
use Netgen\Layouts\Block\BlockDefinition\BlockDefinitionHandlerInterface;
// ... lines 6 - 9
class VerticalWhitespacePlugin extends Plugin
{
public static function getExtendedHandlers(): iterable
{
yield BlockDefinitionHandlerInterface::class;
}
// ... lines 16 - 28
}

That's better.

Now let's try it. Refresh... click on any block... let me find my Title block... and... there it is! On any block we see the new field!

Adding "Child" Parameters/Fields

But, the real idea is that, if the user enables this, we show them two more fields where they can select the top or bottom margin.

To do that, after the first field, I'll paste in two more parameters:

62 lines | src/Layouts/VerticalWhitespacePlugin.php
// ... lines 1 - 9
class VerticalWhitespacePlugin extends Plugin
{
// ... lines 12 - 16
public function buildParameters(ParameterBuilderInterface $builder): void
{
$builder->add(
'vertical_whitespace:enabled',
// ... lines 21 - 26
);
$builder->get('vertical_whitespace:enabled')->add(
'vertical_whitespace:top',
ParameterType\ChoiceType::class,
[
'default_value' => 'medium',
'label' => 'Top Spacing',
'options' => [
'None' => 'none',
'Small' => 'small',
'Medium' => 'medium',
'Large' => 'large',
],
'groups' => [self::GROUP_DESIGN],
],
);
$builder->get('vertical_whitespace:enabled')->add(
'vertical_whitespace:bottom',
ParameterType\ChoiceType::class,
[
'default_value' => 'medium',
'label' => 'Bottom Spacing',
'options' => [
'None' => 'none',
'Small' => 'small',
'Medium' => 'medium',
'Large' => 'large',
],
'groups' => [self::GROUP_DESIGN],
],
);
}
}

These are basically like the first. The big difference is that, up here, we said $builder->add(). But now we have $builder->get('vertical_whitespace:enabled') and then ->add(). This makes these child fields under the first.

This is pretty cool. Refresh and... let's find the Column block. Click to "Enable Vertical Whitespace". Woh! The other two fields showed up! Let's do "Medium" top spacing and "No" bottom spacing. Publish that.

Using the Parameters in the Block Template

It shouldn't be too surprising, however, that when we refresh the page... absolutely nothing happens! We added those options... but we're not using them anywhere yet. We need to override a template to do that.

Let's think: we want this top and bottom margin to apply to every block in the system. And, fortunately, every block in the system eventually extends block.html.twig: this one here in the nglayouts/themes/ directory.

Copy this. Then override it via the theming system. If we follow the path... standard/block... standard/block... the new file should live here: block.html.twig. Paste the contents inside.

To make sure this is working, put a little TEST:

21 lines | templates/nglayouts/themes/standard/block/block.html.twig
{% set css_class = ['ngl-block', 'ngl-' ~ block.definition.identifier, 'ngl-vt-' ~ block.viewType, css_class|default(block.parameter('css_class').value)]|join(' ') %}
{% set css_id = css_id|default(block.parameter('css_id').value) %}
{% set set_container = block.parameter('set_container').value %}
{% if show_empty_wrapper is not defined %}
{% set show_empty_wrapper = false %}
{% endif %}
{% set block_content = (block('content') is defined ? block('content') : '')|trim %}
{% if block_content is not empty or show_empty_wrapper %}
<div class="{{ css_class }}" {% if css_id is not empty %} id="{{ css_id }}" {% endif %}>
TEST
{% if set_container %}<div class="container">{% endif %}
{{ block_content|raw }}
{% if set_container %}</div>{% endif %}
</div>
{% endif %}

Ok! Refresh the frontend. Yikes! Yep, that's definitely working. Go... take that out.

At the top of the template, we have a variable called css_class, which is set to some core classes. And hey! It calls block.parameter('css_class')! Yup, that's what reads the "CSS class" field from the block options!

Then, it uses |join(' ') to combine all of these into a string.

I'm going to remove that join()... then rename this variable to css_classes:

21 lines | templates/nglayouts/themes/standard/block/block.html.twig
{% set css_classes = ['ngl-block', 'ngl-' ~ block.definition.identifier, 'ngl-vt-' ~ block.viewType, css_class|default(block.parameter('css_class').value)] %}
// ... lines 2 - 21

We're setting things up so that we can easily modify that variable. Down here, right before block_content, recreate that css_class variable set to css_classes|join(' '):

21 lines | templates/nglayouts/themes/standard/block/block.html.twig
// ... lines 1 - 8
{% set css_class = css_classes|join(' ') %}
{% set block_content = (block('content') is defined ? block('content') : '')|trim %}
// ... lines 11 - 21

This variable is used in a bunch of different places and in child templates. So we need to make sure it's still set.

Anyways, up here, we now have a css_classes array. Let's use that! I'll paste in three variables, each set to the value of our three parameters:

29 lines | templates/nglayouts/themes/standard/block/block.html.twig
// ... lines 1 - 2
{% set set_container = block.parameter('set_container').value %}
{% set use_whitespace = block.parameter('vertical_whitespace:enabled').value is same as(true) %}
{% set whitespace_top = block.parameter('vertical_whitespace:top').value %}
{% set whitespace_bottom = block.parameter('vertical_whitespace:bottom').value %}
// ... lines 8 - 29

This is where the parameter name we used in the class comes in handy.

Now, very simply, if use_whitespace, then add some margin classes. I'll paste that code in too:

29 lines | templates/nglayouts/themes/standard/block/block.html.twig
// ... lines 1 - 4
{% set use_whitespace = block.parameter('vertical_whitespace:enabled').value is same as(true) %}
{% set whitespace_top = block.parameter('vertical_whitespace:top').value %}
{% set whitespace_bottom = block.parameter('vertical_whitespace:bottom').value %}
{% if use_whitespace %}
{% set css_classes = css_classes|merge(['whitespace-top-' ~ whitespace_top]) %}
{% set css_classes = css_classes|merge(['whitespace-bottom-' ~ whitespace_bottom]) %}
{% endif %}
// ... lines 12 - 29

So, for the top margin, we're adding a new whitespace-top- followed by none, small, medium or large. And same for the bottom.

These new classes are totally invented: they're not part of Bootstrap CSS or anything else, but you could make this smarter to reuse those. But for us, if you open assets/styles/app.css... near the top, here we go!

108 lines | assets/styles/app.css
// ... lines 1 - 12
.whitespace-top-small {
padding-top: 2rem;
}
.whitespace-top-medium {
padding-top: 4rem;
}
.whitespace-top-large {
padding-top: 8rem;
}
.whitespace-bottom-small {
padding-bottom: 2rem;
}
.whitespace-bottom-medium {
padding-bottom: 4rem;
}
.whitespace-bottom-large {
padding-bottom: 8rem;
}
// ... lines 31 - 108

Before the tutorial, I already prepared those classes.

So... it should work! Move over and refresh. Got it! Our block has a little extra top whitespace... which comes from our new class.

And... done!, Woo! Great job team! You're now a Layouts champion! Let us know what cool things you're building with it. And if you have any questions, as always, we're here for you down in the comments section.

Alright, thank you and seeya next time.