auto-model.md

Auto Model

In some cases, developers may not require full control over the data. For such scenarios, Daxus provides a "auto model" feature. With a auto model, you don't need to specify how to sync the fetched data to the model's state, as it handles this internally. Let's take a closer look:

const userModel = createAutoModel();

const getUser = userModel.defineNormalAccessor<User, string>({
  fetchData: async userId => {
    return getUserApi(userId);
  },
});

function useUser(userId: string) {
  return useAccessor(getUser(userId));
}

When using createAutoModel, you don't need to provide an initial state, and there's no need to create an adapter because you don't have to manage how the fetched data is synced to the model's state.

When you are using the accessor defined by an auto model, you don't need to specify a getSnapshot function because Daxus handle it for you. However, you can also specify it to get the data you want:

function useUserName(userId: string) {
  return useAccessor(getUser(userId), { getSnapshot: user => user?.name });
}

Mutation

The auto model also provides a mutate method, but it works slightly differently from the original model. Developers need to provide an accessor to access the corresponding cached data:

userModel.mutate(getUser(userId), prevUser => {
  return { ...prevUser, name: 'new user name' };
});

Note that when using the auto model, you should return a new data object instead of directly mutating the cached data.

Get State

The getState method need to pass an accessor to get the corresponding cache.

userModel.getState(getUser(userId)); // -> User | undefined

Limitation

When using the auto model, you lose some control over the model's state. The data is bound to the accessor, and its definition is derived from the return value of the fetchData function.