Using cache.updateQuery() data is null

urql version & exchanges:

Steps to reproduce

1. go here: https://codesandbox.io/s/urql-svelte-crud-with-indexeddb-cqg5i?file=/urql.js:1152-1179
2. click on “Todos list”
3. click on a “Complete” button, the one you want
4. it gives an error: Cannot set property 'text' of null

Why this error?

Why is data null?

I’m using this code:

import { initClient, dedupExchange, fetchExchange } from "@urql/svelte";
import { offlineExchange } from "@urql/exchange-graphcache";
import { makeDefaultStorage } from "@urql/exchange-graphcache/default-storage";
import gql from "graphql-tag";
import { TODOS_QUERY, TODO_QUERY } from "./gql";

const updates = {
  Mutation: {
    updateTodo: (result, args, cache, info) => {
      if (info.optimistic) {
        cache.updateQuery(
          { query: TODO_QUERY, variables: { id: info.variables.id } },
          data => {
            console.log("data:" + data);
            data.text = "UPDATING";
            return data;
          }
        );
      }
    }
  }
};

const optimistic = {
  updateTodo: () => {}
};

const storage = makeDefaultStorage({
  idbName: "graphcache-v3",
  maxAge: 7
});

const exchanges = [
  dedupExchange,
  offlineExchange({ storage, updates, optimistic }),
  fetchExchange
];

function OnInit() {
  initClient({ url: "https://h1pcl.sse.codesandbox.io", exchanges });
}

export default {
  OnInit
};

[JoviDeCroock]

Optimistic updates are meant to reflect an early answer from the server, using to indicate something is updating isn’t really its use case. This could be done by means of result.fetching instead.

The thing is, optimistic is used to ensure we can actually be offline, when a user is offline and performs a mutation just highlighting that certain thing is updating isn’t of much use to our user, if it’s unsafe to simulate an early response we should doubt that this entity can be mutated in an offline-state.

[JoviDeCroock]

It’s the same as you are doing in updates.Mutation, cache.readFragment with the TodoFragment, id and you should have that data