Scope slots allow child components to expose data to the parent component for custom rendering. 1. The child components bind data through slot tags such as: user="user", 2. The parent component uses v-slot to receive and render; the backup content is used to display the default content when no slot is provided, 3. Write text directly in the slot tag such as "no data yet" as the default value; 4. Use named slots to distinguish multiple slot areas, such as header and main, to achieve more refined layout control.
In Vue development, slots are a very practical feature that allows you to pass content from parent components to child components. When you start using Scoped Slots and Fallback Content, you will find that they greatly enhance the flexibility and reusability of components.
What are scope slots?
Scoping slots allow you to expose some data to the places where the slot is used while defining the slot. This means that the child component can provide data, and the parent component decides how to render it.
For example, suppose you have a component that displays a user list:
<template>
<div>
<slot v-for="user in users" :user="user"></slot>
</div>
</template>
<script>
export default {
data() {
return {
users: [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' }
]
};
}
};
</script>In the parent component you can use it like this:
<template>
<UserList>
<template v-slot="{ user }">
<p>{{ user.name }}</p>
</template>
</UserList>
</template> The key point here is: the child component generates a slot for each user through v-for loop on the slot tag, and exposes user object as a slot prop. The parent component receives this object through v-slot and performs custom rendering.
How to use fallback content?
Fallback content refers to the child component displaying the default content when the parent component does not provide slot content.
For example, you may want to display a prompt message when no user provides slot content:
<template>
<div>
<slot>
Default content: No data yet</slot>
</div>
</template>If the parent component does not pass any slot content, "Default content: No data yet".
Sometimes you can even use fallback content in scope slots. For example:
<template>
<slot :user="user">
User not provided a name</slot>
</template>If the parent component does not have custom rendering logic, the default text is displayed.
Use <template> to distinguish multiple slots
Vue supports named slots, you can specify different slot contents for different regions. Combined with scope slots, more complex layout control can be achieved.
For example, a card component:
<template>
<div class="card">
<header>
<slot name="header"></slot>
</header>
<main>
<slot :user="user"></slot>
</main>
</div>
</template>Use in parent component:
<MyCard>
<template #header>
<h1>User Information</h1>
</template>
<template v-slot="{ user }">
<p>Name: {{ user.name }}</p>
</template>
</MyCard>In this way, you can control the contents of the header and body separately, and the main part can also access the data of the child components.
Tips: Avoid common mistakes
- Forgot to deconstruct slot prop : If you write
<template v-slot="props"></template>, remember to manually accessprops.user. - Fallback content is overwritten : Fallback will only be displayed if there is no slot content. If there are multiple
<slot></slot>, please pay attention to whether the naming is correct. - Scope is only valid inside slot : variables exposed by subcomponents cannot be accessed outside
<slot></slot>.
Basically that's it. Scoping slots and fallback content are very powerful in combination, but it is not complicated to understand their working mechanism.
The above is the detailed content of Understanding Vue Slots with Scope and Fallback. For more information, please follow other related articles on the PHP Chinese website!
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