Svelte:如何处理组件中自定义可写存储的异步初始化承诺? [英] Svelte: How to handle the custom writtable store's async init's promise in the component?
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问题描述
我有几个Svelte组件和一个定制的可写存储。存储有一个init
函数,它是async
,它用一些rest API的数据库的表数据填充存储的值。我的组件都必须使用自动订阅来订阅此存储。订阅时,必须调用init
。全局思想是在数据库上实现CRUD操作,在存储上执行CRUD操作(用于显示存储的值,即数据库的表,并具有反应性)。
init
是async
,因此返回一个承诺,我需要在我的组件中.then .catch
它。但由于我使用自动订阅(通过在商店名称前加上$
),我如何才能做到这一点?
例如:App.svelte
(组件):
<script>
import { restaurant_store } from './Restaurant.js'
export let name
</script>
<main>
<!--- I need to handle the promise and rejection here -->
{#each $restaurant_store as restaurant}
<li>
{restaurant.name}
</li>
{/each}
</main>
Restaurant.js
(商店):
import { writable } from 'svelte/store'
export function createRestaurantsStore() {
const { subscribe, update } = writable({ collection: [] })
return {
subscribe,
init: async () => {
const response = await fetch('http://localhost:1337/restaurants')
if(response.ok) {
const json_response = await response.json()
set({ collection: json_response })
return json_response
}
throw Error(response.statusText)
},
insert: async (restaurant) => {
const response = await fetch('http://localhost:1337/restaurants', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(restaurant)
})
if(response.ok) {
const json_response = await response.json()
update(store_state => store_state.collection.push(json_response))
return json_response
}
throw Error(response.statusText)
},
update: async (restaurant, id) => {
const response = await fetch('http://localhost:1337/restaurants/' + id, {
method: 'PUT',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(restaurant)
})
if(response.ok) {
const json_response = await response.json()
update(store_state => {
const current_id = store_state.collection.findIndex(e => e.id === id)
store_state.collection.splice(current_id, 1, json_response)
})
return json_response
}
throw Error(response.statusText)
}
}
}
export const restaurant_store = createRestaurantsStore()
推荐答案
Svelte提供了一个built-in mechanism来处理模板中承诺的可能状态,因此相同的状态可能如下所示:
<main>
{#await restaurant_store.init()}
<p>waiting for the promise to resolve...</p>
{:then}
{#each $restaurant_store as restaurant}
<li>
{restaurant.name}
</li>
{/each}
{:catch error}
<p>Something went wrong: {error.message}</p>
{/await}
</main>
查看REPL以获取实时示例。
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