无法读取null的属性“executeQuery”
无法读取null的属性“executeQuery”
提问于 2021-09-24 06:33:28
有没有人能帮我理解为什么会出现这个错误：
我的设置：
新的sveltekit项目。graphql的ASP.net核心后端。在我修改它以包含订阅之前，查询是有效的。
错误消息：
Cannot read property 'executeQuery' of null
TypeError: Cannot read property 'executeQuery' of null
at C:\Repos\AGScada\node_modules\@urql\svelte\dist\urql-svelte.js:234:11
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:254:18
at Object.next (C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:1161:14)
at C:\Repos\AGScada\node_modules\@urql\svelte\dist\urql-svelte.js:173:11
at Object.subscribe (C:\Repos\AGScada\node_modules\svelte\store\index.js:53:9)
at Object.subscribe (C:\Repos\AGScada\node_modules\@urql\svelte\dist\urql-svelte.js:96:14)
at C:\Repos\AGScada\node_modules\@urql\svelte\dist\urql-svelte.js:168:14
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:1159:9
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:247:7
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:590:18源代码index.svelte：
import { setClient, query, operationStore, subscription } from '@urql/svelte';
import { createClient, defaultExchanges, subscriptionExchange } from '@urql/svelte';
import { createClient as createWSClient } from 'graphql-ws';
const wsClient = process.browser ? createWSClient({url: 'ws://localhost:5000/graphql',}):null;
const client = process.browser ? createClient({
url: 'http://localhost:5000/graphql',
exchanges: [
...defaultExchanges,
subscriptionExchange({
forwardSubscription: (operation) => ({
subscribe: (sink) => ({
unsubscribe: wsClient.subscribe(operation, sink),
}),
}),
}),
],
}): null;
let tags = operationStore(`query {tags{tagName value}}`);
let onTagUpdated = operationStore(`subscription {onTagUpdated{tagName value}}`);
query(tags);
subscription(onTagUpdated);
setClient(client);
if($tags.fetching)
{
console.log("loading");
}
else
{
console.log($tags.data);
}谢谢你的帮助。
回答 1
Stack Overflow用户
发布于 2021-09-26 11:48:09
我让sveltekit和URQL与订阅支持一起工作。
来源可以在这里找到：https://github.com/ruban258/sveltekit_urql_test
import { Client, setClient, operationStore, subscription, defaultExchanges, subscriptionExchange, query, createClient } from '@urql/svelte';
import {SubscriptionClient} from 'subscriptions-transport-ws';
import { browser } from '$app/env';
import { createClient as createWSClient } from 'graphql-ws';
const subscriptionClient = browser ? new SubscriptionClient('ws://localhost:5000/graphql', { reconnect: true }): null;
const wsClient = browser? createWSClient({
url: 'ws://localhost:5000/graphql',
}):null;
const client = browser ? new Client({
url: 'http://localhost:5000/graphql',
exchanges: [
...defaultExchanges,
subscriptionExchange({
forwardSubscription: (operation) => subscriptionClient.request(operation)
}),
],
}): null;
const messages = operationStore(`
subscription onTagUpdated{
onTagUpdated{
tagName
value
}
}
`);
const tags = operationStore(`
query{
tags{
tagName
value
}
}
`);
const handleSubscription = (messages = [], data) => {
return [data.newMessages, ...messages];
};
setClient(client);页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/69310535
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