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---
id: placeholder-query-data
title: Placeholder Query Data
ref: docs/framework/react/guides/placeholder-query-data.md
---
[//]: # 'ExampleValue'
```ts
class TodosComponent {
result = injectQuery(() => ({
queryKey: ['todos'],
queryFn: () => fetch('/todos'),
placeholderData: placeholderTodos,
}))
}
```
[//]: # 'ExampleValue'
[//]: # 'Memoization'
[//]: # 'Memoization'
[//]: # 'ExampleFunction'
```ts
class TodosComponent {
result = injectQuery(() => ({
queryKey: ['todos', id()],
queryFn: () => fetch(`/todos/${id}`),
placeholderData: (previousData, previousQuery) => previousData,
}))
}
```
[//]: # 'ExampleFunction'
[//]: # 'ExampleCache'
```ts
export class BlogPostComponent {
// Until Angular supports signal-based inputs, we have to set a signal
@Input({ required: true, alias: 'postId' })
set _postId(value: number) {
this.postId.set(value)
}
postId = signal(0)
queryClient = inject(QueryClient)
result = injectQuery(() => ({
queryKey: ['blogPost', this.postId()],
queryFn: () => fetch(`/blogPosts/${this.postId()}`),
placeholderData: () => {
// Use the smaller/preview version of the blogPost from the 'blogPosts'
// query as the placeholder data for this blogPost query
return queryClient
.getQueryData(['blogPosts'])
?.find((d) => d.id === this.postId())
},
}))
}
```
[//]: # 'ExampleCache'
[//]: # 'Materials'
[//]: # 'Materials'
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