Nesting Components

BoxLang

// wires/ContactUs.bx
class extends="cbwire.models.Component" {
    data = {
        "showForm": false
    };  
}

CFML

BoxLang

<!--- wires/contactus.bxm --->
<bx:output>
    <div>
        <bx:if showForm>
            <!--- Nested component --->
            #wire( name="ContactForm" )#
        </bx:if>    
        <button wire:click="$toggle( 'showForm' )">Toggle form</button>
    </div>
</bx:output>

CFML

You can also pass parameters.

BoxLang

// wires/ContactUs.bx
class extends="cbwire.models.Component" {
    data = {
        "showForm": false,
        "sendEmail": false,
        "validateForm": true
    };  
    
    function onMount( params ) {
        data.sendEmail = params.sendEmail;
        data.validateForm = params.validateForm;
    }
}

CFML

BoxLang

<!--- wires/contactus.bxm --->
<bx:output>
    <div>
        <bx:if showForm>
            #wire(
                name="ContactForm"
                params={
                    sendEmail: true,
                    validateForm: true
                }
            )#
        </bx:if>
        <button wire:click="$toggle( 'showForm' )">Toggle form</button>    
    </div>
</bx:output>

CFML

Using Keys with Nested Components

When nesting components, it's important to provide a key to help Livewire understand what's changed when components are updated. This is particularly crucial when you have dynamic nested components that may be added or removed from the DOM.

Why Keys Matter

Livewire treats each nested component as an island, meaning that each child component is truly its own separate UI component with its own data properties and functionality. Refreshing the parent does not automatically refresh the child components. However, sometimes you want to remove or delete child components entirely. The key parameter is what Livewire looks at to determine if a child component still exists or if it should be removed from the DOM.

Without keys, when a parent component refreshes, Livewire may not properly identify which nested components have changed, leading to unexpected behavior or components not being properly cleaned up.

Basic Key Usage

BoxLang

<!--- wires/contactus.bxm --->
<bx:output>
    <div>
        <bx:if showForm>
            <!--- Using a key helps Livewire track this nested component --->
            #wire( name="ContactForm", key="contact-form-#generateUUID()#" )#
        </bx:if>    
        <button wire:click="$toggle( 'showForm' )">Toggle form</button>
    </div>
</bx:output>

CFML

Dynamic Keys for Component Lists

When rendering multiple nested components dynamically, use unique keys to help Livewire track each component individually:

BoxLang

// wires/PostList.bx
class extends="cbwire.models.Component" {
    data = {
        "posts": [
            { "id": 1, "title": "First Post" },
            { "id": 2, "title": "Second Post" },
            { "id": 3, "title": "Third Post" }
        ]
    };

    function removePost(postId) {
        data.posts = data.posts.filter(function(post) {
            return post.id != arguments.postId;
        });
    }
}

CFML

BoxLang

<!--- wires/postlist.bxm --->
<bx:output>
    <div>
        <bx:loop array="#posts#" index="post">
            <!--- Each nested component gets a unique key based on the post ID --->
            #wire( 
                name="PostCard", 
                params={ "post": post },
                key="post-#post.id#"
            )#
        </bx:loop>
    </div>
</bx:output>

CFML

Key Guidelines

• Use unique identifiers: Base keys on database IDs, UUIDs, or other unique values

• Keep keys stable: Don't use random values that change on each render unless you are wanting the child component to load new on every parent refresh

• Be descriptive: Use meaningful key names like "user-#userID#" or "form-#formType#"

• Required for dynamic lists: Always use keys when rendering nested components in loops

• Essential for conditional rendering: Use keys when components are conditionally displayed

When a key changes or is removed, Livewire will destroy the old component and create a new one. This ensures proper cleanup of event listeners, timers, and other component state.

Keys must be unique across all nested components on the page, not just within a single parent component. Duplicate keys can cause rendering issues and unpredictable behavior.