Handing asynchronous requests from stores

[jhollingworth]

When you are getting something from a store, you must assume it will require an asynchronous operation to fetch the data (right now we are only concerned with HTTP requests). Currently if we don't have the data yet we send off an HTTP request and return null/undefined. This approach leaves a number of unanswered questions

• How do you differentiate from the entity not being in the local cache and it not existing at all (e.g. 404/410)
• How you know if there is already an HTTP request in progress which is trying to get the data?
• How do you know if an HTTP request has failed?
• How do you ensure all the stores are synchronised before returning the result of a asynchronous result?
• If a views initial state is not available before the component is mounted, what should we render?

[jhollingworth]

Some ideas

var FooCache = Marty.createCache({
  mixins: [Marty.HttpCache],
  getById: function (id) {
    return this.lock(id, function () {
      if (this.contains(id)) {
        return this.state[id];
      }

      return this.get('/foos/' + id)
    });
  }
});

var FooStore = Marty.createStore({
  mixins: [HttpCache],
  getFoos: function (id) {
    this.getById(id)
  }
});

var FooState = Marty.createStateMixin({
  getState: function () {
    return {
      // if any state values is promises, we wait for them to be resolved
      foo: FooStore.getFoo(id)
    };
  }
});

var FooView = Marty.createStateMixin({
  mixins: [FooState],
  render: function () {

  }
})

[rymohr]

I like where you're going with the PR #29