Local offline syncMap fails to resolve after creation

[BerkliumBirb]

When I declare offline local syncMapTemplate I expect it to be resolved when it's created. This is how I can implement unique check of some fields, for example.

But right now, if I subscribe to non-existent map and then create it, it breaks with Server undid logux/subscribe because of notFound error.

This is reproduction:

import { it } from "node:test" // node 22.12.0
import { syncMapTemplate, createSyncMap, TestClient } from "@logux/client" // version: 0.21.1

it("should resolve with created value if template is local offline", async (t) => {
    const client = new TestClient('static');

    const template = syncMapTemplate('some', {
        offline: true,
        remote: false
    })

    let value
    const store = template('new', client)
    store.subscribe((newValue) => value = newValue)

    await createSyncMap(client, template, { id: 'new', data: true })
    await store.loading
    // ^: Error [LoguxUndoError]: Server undid logux/subscribe because of notFound

    t.assert.equal(value.isLoading, false)
    t.assert.equal(value.data, true)
})

[ai]

It is by design. We expect you to load syncMapTemplate only after you created it.

[ai]

Why do you need to load it before you create it? (I didn’t get what check do you need)

[BerkliumBirb]

I don't know if it's created or not at the time of loading.

In my specific case: I have external IDs and have optional metadata syncMap for that ID (custom avatar, personal notes and stuff). If I find this metadata locally, I'll show something fancy for the person, if there's nothing, I'll just show a boring placeholder avatar.

I found this bug when we implemented metadata add form which is located nearby component that loads syncMap.

Is there any exists() call or something?

[ai]

If I find this metadata locally, I'll show something fancy for the person, if there's nothing, I'll just show a boring placeholder avatar.

You can use loadValue() (with some helper to integrate it to React). It returns undefined.

Or you can just do store.loading.catch (again, it is better to do it with some Promise based helper for React).

[BerkliumBirb]

You can use loadValue()

I can't, because I need to update the avatar when meta is changed. I still need store.subscribe() to work.

you can just do store.loading.catch

So basically I have to suppress this error and resubscribe when I encounter it? Wouldn't that be an infinite subscribe/throw/resubscribe cycle?

[BerkliumBirb]

This is what I came up with so far. It seems to solve my case

import { type SyncMapCreatedAction, type SyncMapValues } from "@logux/actions";
import { LoguxUndoError, type SyncMapStore } from "@logux/client";

export function subscribeUntilFound<
  value extends SyncMapValues,
  store extends SyncMapStore<value>,
>(store: store, listener: Parameters<store["subscribe"]>[0]): () => void {
  const id = store.get().id;

  let unbind = store.subscribe(listener);

  store.loading.catch((reason) => {
    if (
      !(reason instanceof LoguxUndoError) ||
      reason.action.reason !== "notFound"
    )
      throw reason;

    unbind();
    unbind = store.client.type<SyncMapCreatedAction<value>>(
      store.plural + "/created",
      () => {
        unbind();
        unbind = store.subscribe(listener);
      },
      {
        event: "add",
        id,
      },
    );
  });

  return unbind;
}

[ai]

Yes, this helper will work.

[BerkliumBirb]

Shouldn't it be included in the library? I think that handling of this error is pretty tricky.