@tanstack/vue-query does not update data after mutation unless isFetching is explicitly used

[kostik-noir]

Describe the bug

Content is only updated in the component that explicitly uses isFetching in the template

Your minimal, reproducible example

https://codesandbox.io/p/sandbox/4w2vcd

Steps to reproduce

Click "Add" button and compare the content of both UI components

Expected behavior

After clicking the Add button, the contents of both components should be the same.

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

Browser

Tanstack Query adapter

vue-query

TanStack Query version

v.5.73.0

TypeScript version

^5.73.0

Additional context

No response

[kostik-noir]

I partially found the reason.

In my example

// src/api.js

export const getItems = () => {
  return Promise.resolve(data);
};

returns a reference to the same array.
If to replace this code with

// src/api.js

export const getItems = () => {
  return Promise.resolve([...data]);
};

which explicitly returns a new instance of Array then everything works as expected without explicit usage of isFetching.

I don't know if it is a bug or a feature

[DamianOsipiuk]

If you return exactly the same object reference , no update would be scheduled, since there is no reason to update as we got exactly the same thing before.

It works as designed.