getContext Issue

[joshua1]

@stolinski , I am getting the error
getContext(...)` can only be used during component initialisation
from the constructor on the Query Class . I dont see anywhere in the code base where this context is set z = getContext('z') . Are we supposed to set the context in the root layout or how do i get this working

[michal-weglarz]

getContext, and therefore new Query(...) which uses context, has to be called in a client-side Svelte component (and not in *.svelte.ts file, for example). Otherwise you'll get getContext can only be used during component initialisation. If you try to retrieve a context which hasn't been initialized before, you won't get an error, but undefined instead.

From what I can see in the current implementation, getContext is being used to retrieve userId which is then used to create a view hash and retrieve an existing view.
The problem is, because the context is not initialized anywhere in the library code, z.current.userId is always undefined and the client id passed around always defaults to anon.

To make it work we could have:

// src/lib/z.svelte;
export const z = new Z<Schema>({
    server: PUBLIC_SERVER,
    schema,
    userID: 'test-user',
    kvStore: 'mem'
});

// e.g. root +layout.svelte
import { z } from '$lib/z.svelte';
setContext('z', z);

It'd be enough to mention that in the README, but I'm not sure if it's ideal as it makes the user of the library responsible for its internal implementation to work correctly.

That being said, the React implementation (which relies on clientID to generate the view hash) seems to be using the global context approach, with the hard requirement of wrapping your entire app with ZeroProvider at the root level:

const z = new Zero({...});

createRoot(document.getElementById("root")!).render(
  <ZeroProvider zero={z}>
    <App />
  </ZeroProvider>
);

zero-solid, on the other hand, doesn't seem to be using userId for hashing at all and doesn't require access to the global context.

[stolinski]

I do wonder if we need the userId for hashing given zero-solid doesn't do it and it does add more complexity that's probably not needed.

[robert-wettstaedt]

In my PR I added a setContext('z', ...) in the constructor of the Z class. So the context will be automatically created when Z is initialized.

This means however, that Z needs to be initialized in a Svelte component (which I do not do in my app for example), but I also added an error message to notify users about this.

[PeteJStewart]

@michal-weglarz solution worked for me:

// src/lib/z.svelte;
export const z = new Z<Schema>({
    server: PUBLIC_SERVER,
    schema,
    userID: 'test-user',
    kvStore: 'mem'
});

// e.g. root +layout.svelte
import { z } from '$lib/z.svelte';
setContext('z', z);

You should definitely update the example in the readme, as I'm pretty sure the example on there doesn't work anymore.

[stolinski]

Guidance here coming this afternoon along with a decent update.