[feature request] alterItems allows async func?

[beeplin]

Now alterItems only works for sync func. Sometimes we need another alterItemsAsync to handle async funcs.

[eddyystop]

Could an IIFE async/await be used?

alterItems(rec => {
  rec.userRecord = (async () => await service.get(...) )()
})

The problem with supporting an async func is that the hook is designed to modify the data/result object in place, so the return value is ignored.

We could have a spurious return value. If that is a Promise, we can wait on it to resolve and only then resolve the returned hook value.. Something similar to

return context => {
    const result = predicate(context);
    if (!result || typeof result.then !== 'function') {
      return !result;
    }

    return result.then(result1 => !result1);
  };

The only way I can see to return such a spurious Promise would be

alterItemsModified(rec => new Promise(resolve => {
  service.get(...).then(result => {
    rec.userRecord = result;
    resolve();
}});

Comments?

[eddyystop]

Handled by #313

@beeplin please let me know if there are any issues.

[eddyystop]

Documentation updated.