Getting started

Twig Hooks are a robust and powerful alternative to the Sonata Block Events and the old Sylius Template Events systems.

Main features

• built-in support for Twig templates, Twig Components and Symfony Live Components

• adjustability

• autoprefixing hooks

• configurable hookables

• priority mechanism

• easy enable/disable mechanism for each hook

Installation

Install the package using Composer and Symfony Flex:

composer require sylius/twig-hooks

Your first hook & hookable

Once Twig Hooks is installed, you can open any Twig file and define your first hook.

some.html.twig

{% hook 'my_first_hook' %}

This way, my_first_hook becomes a unique name which we can use to hook into that specific spot.

The ideal hook name:

• is lowercase

• has its logical parts separated with dots (.)

• when there is more than one word, they are separated by underscores (_)

Recommended:

• index

• index.sidebar

• index.top_menu

Not recommended:

• index

• indextopmenu

Hooking into a hook

For the purpose of this example, let's consider we want to render the some_block.html.twig template inside the my_first_hook hook. First step is to create a twig_hooks.yaml file (or any other format you use) under the config/packages/ directory (if you don't have one already, of course).

Now, we can define our first hookable with the following configuration:

config/packages/twig_hooks.yaml

sylius_twig_hooks:
    hooks:
        'my_first_hook':
            some_block:
                template: 'some_block.html.twig'

Decomposing the example above we can notice that:

1. sylius_twig_hooks is the main key for Twig Hooks configuration

2. hooks is a configuration key for defining hookables for all hooks

3. my_first_hook is our hook name, defined on the Twig file level

4. some_block is the name of our hookable, it can be any string, but it should be unique for a given hook unless you want to override the existing hookable (if you want to read more about overriding hookables check the overriding-hookables.md section)

5. finally we have a template key that defines which template should be rendered inside the my_first_hook hook

Possible hookable configuration options

Depending on the hookable template, we can pass different configuration options while defining hookables:

Hookable Template

sylius_twig_hooks:
    hooks:
        'my_first_hook':
            some_block:
                template: 'some_block.html.twig'
                enabled: true # whether the hookable is enabled
                context: [] # key-value pair that will be passed to the context bag
                configuration: [] # key-value pair that will be passed to the configuration bag
                condition: '@=user != null' # expression evaluated at runtime; the hookable is rendered only when it returns true
                priority: 0 # priority, the higher the number, the earlier the hookable will be hooked

Hookable Component

sylius_twig_hooks:
    hooks:
        'my_first_hook':
            some_block:
                component: 'app:block' # component key
                enabled: true # whether the hookable is enabled
                context: [] # key-value pair that will be passed to the context bag
                props: [] # key-value pair that will be passed to our component as props
                configuration: [] # key-value pair that will be passed to the configuration bag
                condition: '@=user != null' # expression evaluated at runtime; the hookable is rendered only when it returns true
                priority: 0 # priority, the higher the number, the earlier the hookable will be hooked

Conditions in hookables

Unlike the enabled flag — which is evaluated statically during the application boot — the condition option is an Expression Language expression that is evaluated at runtime, each time the hook is rendered. The hookable is rendered only when the expression returns true. Both the whole hook context and the _context variable are available within the expression, so both of these work:

condition: '@=user != null'
condition: '@=_context.user != null'

The user variable is provided from Symfony's current security token, as in Symfony security expressions. To refer to a user value passed explicitly in the hook context, use _context.user. For context keys, _context behaves like Twig's defined-style check: @=_context.product returns null when the variable is absent from the context. Referencing a missing variable directly (e.g. @=product ...) throws a clear InvalidExpressionException instead, which makes invalid conditions fail fast during development.

Conditions can also use Symfony's is_granted() authorization check. Pass the required role or attribute, and optionally a subject:

condition: '@=is_granted("ROLE_ADMIN")'
condition: '@=is_granted("EDIT", _context.product)'

The check uses Symfony's authorization checker, so voters and access decision rules apply as they do in Twig templates.

On Symfony 7.1 and newer, conditions are validated at the application boot: an invalid expression is reported as soon as the container is compiled. On older versions, errors are only reported at runtime, when the hook is rendered.