Revision: Tue, 30 May 2023 16:57:30 GMT
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Stempler - Directives

In addition to the classic echo constructions, Stempler supports many Blade-like directives to control the business logic of your templates.

Unlike Blade or Twig, Stempler directives are only responsible for managing business logic.

See Components and Props and Inheritance to check how to extend your templates and implement virtual components.

Escaping control '@' letter

Just double 'at' letter like

php
@@ // -> will be rendered as '@'

Loop Directives

To loop over a list of template variables, use the following directives.

Note
The directive declaration is similar to native PHP syntax.

Embed PHP

To embed PHP logic in your template, use the classic <?php and ?> tags or alternative @php and @endphp:

php
@php
    echo "hello world";
@endphp

For

Use the directive @for and @endfor to render the loop:

php
@for($i=0; $i<100; $i++)
    hello
@endfor

While

Use the directive @while and @endwhile to render while loop:

php
@php $i = 0; @endphp
@while($i < 10)
    hello world
    @php $i++; @endphp
@endwhile

Break and Continue

Use the @break and @continue directives to interrupt your loops:

php
@php $i = 0; @endphp
@while(true)
    hello world
    @if($i++>10)
        @break
    @endif
@endwhile

Note
@break(2) is equivalent to break 2. Read more about if directives below.

Conditional Directives

Stempler provides some conditional directives which transcribed into native PHP code.

The examples are given with the following variables:

php
return $this->views->render('welcome', [
    'value' => 123
]);

If and Else

To create a conditional statement, use the @if and @endif directives:

php
@if($value === 123)
    {{ "hello world" }}
@endif

To create an else condition, use the @else directive:

php
@if($value !== 123)
    {{ "value is not 123" }}
@else
    {{ "value is 123" }}
@endif

To create a conditional else use elseif:

php
@if($value === 124)
    {{ "value is 124" }}
@elseif($value === 123)
    {{ "value is 123" }}
@else
    {{ "another value" }}
@endif

Unless

Use the @unless directive to declare a negative condition:

php
@unless($value === 124)
    {{ "value is not 124" }}
@endunless

Note
You can use @else and @elseif with the @unless directive.

Empty and Isset

Use the @empty and @isset conditions and @endempty, @endisset accordingly:

php
@empty($value)
    value is empty
@endempty

@isset($value)
    value is set
@endisset

Note
You can combine this condition with @else, @elseif.

Switch case

To create more complex conditions, use the @swich, @case, @break and @endswitch statements.

php
@switch($value)
    @case(123) 123 @break
    @case(124) 124 @break
    @case(125) 125 @break
@endswitch

Json Directive

To render JSON on a page, use the @json directive:

php
@json($value)

You can embed json inside JavaScript statements:

php
return $this->views->render('welcome', [
    'value' => ['key' => 'value']
]);

In your template:

php
<script type="text/javascript">
    var value = @json($value);
    console.log(value.key);
</script>

Alternatively, you can use the contextual echo via the {{ }} statement:

php
<script type="text/javascript">
    var value = {{ $value  }};
    console.log(value.key);
</script>

In both cases, the generated view will look like this:

php
<script type="text/javascript">
    var value = {"key":"value"};
    console.log(value.key);
</script>

Framework specific directives

Spiral provides a number of framework-specific directives.

Container

To invoke a container dependency into a template, use the @inject($variable, "class") directive:

php
@inject($app, App\App::class)
{{ get_class($app) }}

Route

To create a route, use the directive @route:

php
<a href="@route('home:index')">click me</a>

You can use the controller:action pattern for targets handled by a default route or route name:

php
$router->addRoute(
    'html',
    new Route('/<action>.html', new Controller(HomeController::class))
);

Pass arguments using the second parameter:

php
<a href="@route('html', ['action' => 'index'])">click me</a>

The parameters will be automatically slugified into the route url. Those parameters that are not found in the route pattern will be passed as query parameters:

php
<a href="@route('html', ['action' => 'index', 'id' => 10])">click me</a>

The result /index.html?id=10.

Read more about routing and named routes here.

Custom Directives

You can declare and register custom directives. To create a custom directive, create a class that extends Spiral\Stempler\Directive\AbstractDirective. Directive methods must be prefixed with render and accept Spiral\Stempler\Node\Dynamic\Directive as a parameter:

php
namespace App\Directive;

use Spiral\Stempler\Directive\AbstractDirective;
use Spiral\Stempler\Node\Dynamic\Directive;

class CustomDirective extends AbstractDirective
{
    public function renderCustom(Directive $directive): string
    {
        return '<?php echo "custom" ?>';
    }
}

Note
You can also implement Spiral\Stempler\Directive\DirectiveRendererInterface to gain lower-level access to functionality.

Register your directive in one of your bootloaders via the StemplerBootloader->addDirective method:

php
namespace App\Bootloader;

use App\Directive\CustomDirective;
use Spiral\Boot\Bootloader\Bootloader;
use Spiral\Stempler\Bootloader\StemplerBootloader;

class CustomDirectiveBootloader extends Bootloader
{
    protected const DEPENDENCIES = [
        StemplerBootloader::class
    ];

    public function boot(StemplerBootloader $stempler): void
    {
        $stempler->addDirective(CustomDirective::class);
    }
}

Invoke the directive in your template:

php
@custom

Passing values

To access values passed to a directive, use the body and values properties of Directive retrospectively:

php
class CustomDirective extends AbstractDirective
{
    public function renderCustom(Directive $directive): string
    {
        return $directive->body;
    }
}

Example:

php
@custom(1, "hello world")

Output:

php
"hello world"

Note
Make sure to check if body is not NULL.

To access specific directive values separated by ,:

php
class CustomDirective extends AbstractDirective
{
    public function renderCustom(Directive $directive): string
    {
        return \sprintf(
            '<?php echo (%s > %s) ? "first value larger or equals": "second value larger" ?>',
            $directive->values[0],
            $directive->values[1]
        );
    }
}

Example:

php
@custom(1, 2)

Directive values will be supplied in their original PHP form, you must escape the values manually. The following PHP will be generated for the Directive above:

php
<?php echo (3 > 2) ? "first value larger or equals": "second value larger" ?>

Note
You can pass $variables into directives as well.

Directive Context

To capture where a directive is invoked from, use $directive->getContext()->getPath():

php
public function renderCustom(Directive $directive): string
{
    return '<?php echo "invoked from ' . var_export($directive->getContext()->getPath(), true) . '" ?>';
}

Note
The output: invoked from 'welcome'.