Handling Requests for hasMany Relationships in Open Event Front-end

In Open Event Front-end we use Ember Data and JSON API specs to integrate the application with the server. Ember Data provides an easy way to handle API requests, however it does not support a direct POST for saving bulk data which was the problem we faced while implementing event creation using the API.

In this blog we will take a look at how we implemented POST requests for saving hasMany relationships, using an example of sessions-speakers route to see how we saved the tracks, microlocations & session-types. Lets see how we did it.

Fetching the data from the server

Ember by default does not support hasMany requests for getting related model data. However we can use external add on which enable the hasMany Get requests, we use ember-data-has-many-query which is a great add on for querying hasMany relations of a model.

let data = this.modelFor('events.view.edit');
data.tracks = data.event.get('tracks');
data.microlocations = data.event.get('microlocations');
data.sessionTypes = data.event.get('sessionTypes');
return RSVP.hash(data);

In the above example we are querying the tracks, microlocations & sessionTypes which are hasMany relationships, related to the events model. We can simply do a to do a GET request for the related model.

data.event.get('tracks');

In the above example we are retrieving the all the tracks of the event.

Sending a POST request for hasMany relationship
Ember currently does not saving bulk data POST requests for hasMany relations. We solved this by doing a POST request for individual data of the hasMany array.

We start with creating a `promises` array which contains all the individual requests. We then iterate over all the hasMany relations & push it to the `promises` array. Now each request is an individual promise.

let promises = [];

promises.push(this.get('model.event.tracks').toArray().map(track => track.save()));
promises.push(this.get('model.event.sessionTypes').toArray().map(type => type.save()));
promises.push(this.get('model.event.microlocations').toArray().map(location => location.save()));

Once we have all the promises we then use RSVP to make the POST requests. We make use of all() method which takes an array of promises as parameter and resolves all the promises. If the promises are not resolved successfully then we simply notify the user using the notify service, else we redirect to the home page.

RSVP.Promise.all(promises)
  .then(() => {
    this.transitionToRoute('index');
  }, function() {
    this.get('notify').error(this.l10n.t(Data did not save. Please try again'));
  });

The result of this we can now retrieve & create new tracks, microlocations & sessionTypes on sessions-speakers route.

Thank you for reading the blog, you can check the source code for the example here.

Resources

 

Implementing Registration API in Open Event Front-end

In this post I will discuss how I implemented the registration feature in Open Event Front-end using the Open-Event-Orga API. The project uses Ember Data for consumption of the API in the ember application. The front end sends POST request to Open Event Orga Server which verifies and creates the user.

We use a custom serialize method for trimming the request payload of the user model by creating a custom user serializer. Lets see how we did it.

Implementing register API

The register API takes username & password in the payload for a POST request which are validated in the register-form component using the semantic-ui form validation. After validating the inputs from the user we bubble the save action to the controller form the component.

submit() {
  this.onValid(() => {
    this.set('errorMessage', null);
    this.set('isLoading', true);
    this.sendAction('submit');
  });
}

In controller we have `createUser()` action where we send a POST request to the server using the save() method, which returns a promise.

createUser() {
  var user = this.get('model');
  user.save()
    .then(() => {
      this.set('session.newUser', user.get('email'));
      this.set('isLoading', false);
      this.transitionToRoute('login');
    })
    .catch(reason => {
      this.set('isLoading', false);
      if (reason.hasOwnProperty('errors') && reason.errors[0].status === 409) {
        this.set('errorMessage', this.l10n.t('User already exists.'));
      } else {
        this.set('errorMessage', this.l10n.t('An unexpected error occurred.'));
      }
    });
}

The `user.save()` returns a promise, therefore we handle it using a then-catch clause. If the request is successful, it executes the `then` clause where we redirect to the login route. If the request fails we check if the status is 409 which translates to a duplicate entry i.e the user already exists in the server.

Serializing the user model using custom serializer

Ember lets us customise the payload using serializers for models. The serializers have serialize function where we can trim the payload of the model. In the user serializer we check if the request is for record creation using `options.includeId`. If the request is for record creation we trim the payload using the lodash `pick` method and pick only email & password for payload for POST request.

serialize(snapshot, options) {
  const json = this._super(...arguments);
  if (options && options.includeId) {
    json.data.attributes = pick(json.data.attributes, ['email', 'password']);
  }
  return json;
}

Thank you for reading the blog, you can check the source code for the example here.

Resources