Implementing Users API to Display the Users at Admin Route in Open Event Frontend

This article will illustrate how the users are displayed and updated on the /admin/users route, their roles, user links etc. using the users API in Open Event Frontend. The primary end point of Open Event API with which we are concerned with for fetching the users is

GET /v1/users

First, we need to create a model for the user, which will have the fields corresponding to the API, so we proceed with the ember CLI command:

ember g model user

Next, we need to define the model according to the requirements. The model needs to extend the base model class. As a user can have multiple notifications, orders and  sessions etc. so we have to use ember data relationships “hasMany”. Hence, the model will have the following format.

import ModelBase from 'open-event-frontend/models/base';
import { hasMany } from 'ember-data/relationships';

export default ModelBase.extend({
  email        : attr('string'),
  password     : attr('string'),
  isVerified   : attr('boolean', { readOnly: true }),
  isSuperAdmin : attr('boolean', { readOnly: true }),
  isAdmin      : attr('boolean', { readOnly: true }),
  firstName : attr('string'),
  lastName  : attr('string')
});

The complete code for the model can be seen here

Now, we need to load the data from the API using the above model, so we will send a GET request to the API to fetch the users. This can be easily achieved using this.

return this.get('store').query('user', {'page[size]': 10 });

The above line is querying for the users from the store which is place where cache of all of the records that have been loaded by our application is there. If a route asks for a record, the store can return it immediately if it is there in the cache and we want to display only 10 users in a page so defined how many number of users has to be loaded at a time.

Now we need to filter the users based on whether they are active or they have deleted their accounts. For this purpose, we need to pass filter to the query which will tell what type of users to be loaded at once.

The next thing we need to do is to display the above data fetched from the API into an ember table. Ember table helps in allowing us to render very large data sets by only rendering the rows that are being displayed. For this, we defined a controller class which will help in letting the table know what all columns will be required to display and the attribute values they correspond in the API. We can also define the template for each column. The code for the controller class looks like this.

import Ember from 'ember';

const { Controller } = Ember;
export default Controller.extend({
  columns: [
    {
      propertyName     : 'first-name',
      title            : 'Name',
      disableSorting   : true,
      disableFiltering : true
    },
    {
      propertyName     : 'email',
      title            : 'Email',
      disableSorting   : true,
      disableFiltering : true
     },
     {
      propertyName     : 'last-accessed-at',
      title            : 'Last Accessed',
      template         : 'components/ui-table/cell/admin/users/cell-last-accessed-at',
      disableSorting   : true,
      disableFiltering : true
    }
   ]
});

In the above code, we can see a field called ‘disableSorting’ which is true if we don’t want to sort the table based on that column. Since we want the last-accessed-at column to be customized, so we have separately added a template for the column which will ensure how it will look in the column. The complete code for the other columns which are there in table apart from these can be found here.

Now to display the ember table we will write the following code.

{{events/events-table columns=columns data=model
    useNumericPagination=true
    showGlobalFilter=true
    showPageSize=true
}}

In the above piece of code, we are calling the same ember table as we used in case of events to reduce the code duplication. We are passing the columns and data in the table which remains unique to the table. Next, we are ensuring that our page shows the amount of data we’re fetching at one go, allows the filtering the table based on the columns.

The UI of the users page for the above code snippets look like this.

Fig 1: The UI of the users table under admin/users route

The entire code for implementing the users API can be seen here.

To conclude, this is how we efficiently fetched the users using the Open-Event-Orga users API, ensuring that there is no unnecessary API call to fetch the data and no code duplication using the same ember table again.

Resources:

Implement Sessions API for the ‘admin/sessions’ Route in Open Event Frontend

In Open Event Frontend, under the ‘admin/sessions’ route, the admin can track the record of the sessions. The info which is shown along with the sessions is the speakers for the session, its title, submitted date, start time, end time. So to integrate the sessions API, we followed the following approach:

Firstly, we add a sessions model and establish its relationship with the speakers model since we need speaker names also:

export default ModelBase.extend({
  title         : attr('string'),
  subtitle      : attr('string'),
  startsAt      : attr('moment'),
  endsAt        : attr('moment'),
  j
  sessionType   : belongsTo('session-type'),
  microlocation : belongsTo('microlocation'),
  track         : belongsTo('track'),
  speakers      : hasMany('speaker'),
  event         : belongsTo('event'), // temporary
});

After creating the model for sessions, we do the query to get the sessions.
Since, the sessions here are classified into the sections like ‘pending’, ‘accepted’, ‘rejected’, ‘deleted’, etc, we need to filter the response returned by the query:

if (params.sessions_state === 'pending') {
      filterOptions = [
        {
          name : 'state',
          op   : 'eq',
          val  : 'pending'
        }
      ];
    } else if (params.sessions_state === 'accepted') {
      filterOptions = [
        {
          name : 'state',
          op   : 'eq',
          val  : 'accepted'
        }
      ];
    }

Above code shows how we filter the response on the server side itself. Hence we pass the filterOptions array to the query as follows:

return this.get('store').query('session', {
      include      : 'event,speakers',
      filter       : filterOptions,
      'page[size]' : 10
});

Once we get data from the query, we just pass it to our controller to implement the columns.
Once we retrieve data from the query, we just pass it to our controller to implement the columns. Since, we are using a different way to render the ember data in the column, the approach goes as follows:
In our controller we do:

export default Controller.extend({
  columns: [
    {
      propertyName   : 'event.name',
      title          : 'Event Name',
      disableSorting : true
    },
    {
      propertyName : 'title',
      title        : 'Title'
    },
    {
      propertyName   : 'speakers',
      template       : 'components/ui-table/cell/cell-speakers',
      title          : 'Speakers',
      disableSorting : true
    }
  ]
});

I have shown here only limited columns, there are others too. Here, we are mapping the propertyName to the attribute returned by the server. Also the ‘title’ indicates the column name. We can also create a custom template(as a component) if we want customization while rendering the data in the rows and columns. For example, if we want to iterate the multiple speaker names for a session, we can do:

<div class="ui list">
  {{#each record.speakers as |speaker|}}
    <div class="item">
      {{speaker.name}}
    </div>
  {{/each}}
</div>

As a result, we can make custom templates for a particular property. Another example of formatting the response is:

<span>
  {{moment-format record.startsAt 'MMMM DD, YYYY - HH:mm A'}}
  {{moment-format record.endsAt 'MMMM DD, YYYY - HH:mm A'}}
</span>

Thus, we get the following view after integration of API:

Resources:

Ember data Official guide

Blog on medium: By “Embedly” publication

Customising URL Using Custom Adapters in Open Event Front-end

Open-Event Front-end uses Ember data for handling Open Event Orga API which abides by JSON API specs. The API has relationships which represent models in the database, however there are some API endpoints for which the URL is not direct. We make use of custom adapter to build a custom URL for the requests.
In this blog we will see how to Implement relationships which do not have a model in the API server. Lets see how we implemented the admin-statistics-event API using custom adapter?

Creating Order-statistics model
To create a new model we use ember-cli command:

ember g model admin-statistics-event

The generated model:

export default ModelBase.extend({
  draft     : attr('number'),
  published : attr('number'),
  past      : attr('number')
})

The API returns 3 attributes namely draft, published & past which represent the total number of drafted, live and past event in the system. The admin-statistics-event is an admin related model.
Creating custom adapter
To create a new adapter we use ember-cli command:

ember g adapter event-statistics-event

If we try to do a GET request the URL for the request will be ‘v1/admin-statistics-event’ which is an incorrect endpoint. We create a custom adapter to override the buildURL method.

buildURL(modelName, id, snapshot, requestType, query) {
  let url = this._super(modelName, id, snapshot, requestType, query);
  url = url.replace('admin-statistics-event', 'admin/statistics/event');
  return url;
}

We create a new variable url which holds the url generated by the buildURL method of the super adapter. We call the super method using ‘this._super’. We will now replace the ‘admin-statistics-event’ with ‘admin/statistics/event’ in url variable. We return the new url variable. This results in generation of correct URL for the request.
Thank you for reading the blog, you can check the source code for the example here.
Resources

Implementing Admin Statistics Mail and Session API on Open Event Frontend

This blog article will illustrate how the admin-statistics-mail and admin-statistics-session API  are implemented on the admin dashboard page in Open Event Frontend.Our discussion primarily will involve the admin/index route to illustrate the process.The primary end points of Open Event API with which we are concerned with for fetching the admin statistics  for the dashboard are

GET /v1/admin/statistics/mails
GET /v1/admin/statistics/sessions

First we need to create the corresponding models according to the type of the response returned by the server , which in this case will be admin-statistics-event and admin-statistics-sessions, so we proceed with the ember CLI commands:

ember g model admin-statistics-mail
ember g model admin-statistics-session

Next we define the model according to the requirements. The model needs to extend the base model class, and all the fields will be number since the all the data obtained via these models from the API will be numerical statistics

import attr from 'ember-data/attr';
import ModelBase from 'open-event-frontend/models/base';

export default ModelBase.extend({
 oneDay     : attr('number'),
 threeDays  : attr('number'),
 sevenDays  : attr('number'),
 thirtyDays : attr('number')
});

And the model for sessions will be the following. It too will consist all the attributes of type number since it represents statistics

import attr from 'ember-data/attr';
import ModelBase from 'open-event-frontend/models/base';

export default ModelBase.extend({
 confirmed : attr('number'),
 accepted  : attr('number'),
 submitted : attr('number'),
 draft     : attr('number'),
 rejected  : attr('number'),
 pending   : attr('number')
});

Now we need to load the data from the api using the models, so will send a get request to the api to fetch the current permissions. This can be easily achieved via a store query in the model hook of the admin/index route.However this cannot be a normal get request. Because the the urls for the end point are /v1/admin/statistics/mails & /v1/admin/statistics/sessions but there are no relationships between statistics and various sub routes, which is what ember’s default behaviour would expect.

Hence we need to override the generated default request url using custom adapters and use buildUrl method to customize the request urls.

import ApplicationAdapter from './application';

export default ApplicationAdapter.extend({
 buildURL(modelName, id, snapshot, requestType, query) {
   let url = this._super(modelName, id, snapshot, requestType, query);
   url = url.replace('admin-statistics-session', 'admin/statistics/session');
   return url;
 }
});

The buildURL method replaces the the default  URL for admin-statistics-session  with admin/statistics/session otherwise the the default request would have been

GET v1/admin-statistics-session

Similarly it must be done for the mail statistics too. These will ensure that the correct request is sent to the server. Now all that remains is making the requests in the model hooks and adjusting the template slightly for the new model.

model() {
   return RSVP.hash({
         mails: this.get('store').queryRecord('admin-statistics-mail', {
       filter: {
         name : 'id',
         op   : 'eq',
         val  : 1
       }
     }),
     sessions: this.get('store').queryRecord('admin-statistics-session', {
       filter: {
         name : 'id',
         op   : 'eq',
         val  : 1
       }
     })
   });
 }


queryRecord is used instead of query because only a single record is expected to be returned by the API.

Resources

Tags :

Open event, Open event frontend, ember JS, ember service, semantic UI, ember-data, ember adapters,  tickets, Open Event API, Ember models

Implementing Notifications API in Open Event Frontend

In Open Event Frontend, at the index page of the application, we have a notification dropdown in which a user gets the notifications regarding the events, sessions, etc. Thus, a user gets notified for the particular event or session he wants to receive notifications about. While dealing with an issue, we had to integrate the API with the frontend. We achieved it as follows:

First, we create a model of notifications so that we have basic structure ready. It goes as follows:

export default ModelBase.extend({
  title      : attr('string'),
  message    : attr('string'),
  isRead     : attr('boolean', { defaultValue: false }),
  receivedAt : attr('moment'),

  user: belongsTo('user')
});

Thus, we have fields like title, message, isRead, receivedAt which we will get from the server response as JSON which we will need to show on the page. To show the notifications to the user, first we need to query the notifications for a specific user using ember data. Since we are querying the notifications for a specific user when he is logged in, we are also having relationship between user and notification as shown in the above notification model. In user model we do:

notifications: hasMany('notification')

Now, we query the notifications in our application route i.e routes/application.js

model() {
    if (this.get('session.isAuthenticated')) {
      return new RSVP.Promise((resolve, reject) => {
        this.store.findRecord('user', this.get('authManager.currentUser.id'), { reload: true })
          .then(user => {
            user.get('notifications').then(resolve).catch(reject);
          })
          .catch(reject);
      });
    }
  }

The reason why we used a RSVP promise here was because the authManager couldn’t load the user befor the notifications were queried and returned. Thus, we query the notifications by using currentUser from authManager. Thus, in our template, we iterate over our notifications as follows:

    {{#each notifications as  notification }}
      <div class="item">
        <div class="header">
          {{notification.title}}
        </div>
        <div class="content weight-600">
          {{notification.description}}
        </div>
        <div class="left floated content">
          {{moment-from-now notification.createdAt}}
        </div>
      </div>
    {{/each}}

The notifications are thus shown to the user when he clicks the icon in the nav-bar. As a result, we get the following notifications in the dropdown:

Resources:

Ember data official guide

Blog on Ember data by Embedly.

Implementing Email Notifications in Open Event Frontend

In Open Event Frontend, we have a ‘settings/email-preferences’ route where we give the user an access to change the email-notifications that he wants to subscribe for a specific event. For now, we are having three notifications for an event which the user can toggle to on and off. To achieve this, we did the following things:

First, we create a model for email-notifications so as to have a skeleton of the data that we are going to receive from the JSON API.

export default ModelBase.extend({

  /**
   * Attributes
   */

  nextEvent           : attr('boolean'),
  newPaper            : attr('boolean'),
  sessionAcceptReject : attr('boolean'),
  sessionSchedule     : attr('boolean'),
  afterTicketPurchase : attr('boolean'),

  /**
   * Relationships
   */
  user  : belongsTo('user'),
  event : belongsTo('event')
});

Thus, above code shows the attributes which we are going to receive via our JSON API and we will render the data accordingly on the page. We have established the relationship of the email-notifications with user and event so that in future wherever needed, we can query the records from either side. The client side has checkboxes to show the data to the user. Following is the format of the checkboxes:

<div class="row">
        <div class="column eight wide">
          {{t 'New Paper is Submitted to your Event'}}
        </div>
        <div class="ui column eight wide right aligned">
          {{ui-checkbox class='toggle' checked=preference.newPaper onChange=(pipe-action (action (mut preference.newPaper)) (action 'savePreference' preference))}}
        </div>
      </div>
      <div class="row">
        <div class="column eight wide">
          {{t 'Change in Schedule of Sessions in your Event'}}
        </div>
        <div class="ui column eight wide right aligned">
          {{ui-checkbox class='toggle' checked=preference.sessionSchedule onChange=(pipe-action (action (mut preference.sessionSchedule)) (action 'savePreference' preference))}}
        </div>
      </div>

The states of the checkboxes are determined by the data that we receive from the API. For example, if for a record, the API returns:

nextEvent           : true,
newPaper            : false,
sessionAcceptReject : true,
sessionSchedule     : false,
afterTicketPurchase : false,

Then, the respective states will be shown by the checkbox and the user can toggle the states to change the email-preferences as they want.

Thus to get the data sent by the server to the client, we return it as a model and query it as:

model() {
    return this.get('authManager.currentUser').query('emailNotifications', { include: 'event' });
}

As we can see, as mentioned earlier, we kept the relationships so that we can query the email-notifications specific to the particular user or specific to particular event. Here, we are showing a user’s email-notifications and hence we queried it with the user relationship.
The authManager loads the currentUser and queries the email-notifications for a particular use. We also want the event details to show the email-preferences, hence we include the event model to be fetched in the query also.

We also let the user change the preferences of the email-notifications so that he can customise the notifications and keep the ones he wants to receive. We implement the updating of email-preferences API as follows:

Whenever a user toggles the checkbox, we are having an action as called ‘savePreference’, which handles the updation of the preferences.

 

{{ui-checkbox class='toggle' checked=preference.newPaper onChange=(pipe-action (action (mut preference.newPaper)) (action 'savePreference' preference))}}

savePreference(emailPreference) {
      emailPreference.save()
        .then(() => {
          this.get('notify').success(this.l10n.t('Email notifications updated successfully'));
        })
        .catch(() => {
          emailPreference.rollbackAttributes();
          this.get('notify').error(this.l10n.t('An unexpected error occurred.'));
        });
    }

We are passing the parameter(the whole preference object to the action), and then just performing a ‘save’ method on it which will send a PATCH request to the server to update the data.

Thus, in this way, the user can change the email-notification preferences in the Open Event Frontend.

Resources:
Ember data Official guide
Blog on Models and Ember data by Daniel Lavigne: Learning Ember.js Part 4: Models

Source code: https://github.com/fossasia/open-event-frontend/pull/537/files

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 User Permissions API on Open Event Frontend to View and Update User Permission Settings

This blog article will illustrate how the user permissions  are displayed and updated on the admin permissions page in Open Event Frontend, using the user permissions API. Our discussion primarily will involve the admin/permissions/index route to illustrate the process.

The primary end point of Open Event API with which we are concerned with for fetching the permissions  for a user is

GET /v1/user-permissions

First we need to create a model for the user-permissions, which will have the fields corresponding to the api, so we proceed with the ember CLI command:

ember g model user-permission

Next we define the model according to the requirements. The model needs to extend the base model class, and other than the name and description all the fields will be boolean since the user permissions frontend primarily consists of checkboxes to grant and revoke permissions. Hence the model will be of the following format.

import attr from 'ember-data/attr';
import ModelBase from 'open-event-frontend/models/base';

export default ModelBase.extend({
 name           : attr('string'),
 description    : attr('string'),
 unverifiedUser : attr('boolean'),
 anonymousUser  : attr('boolean')
});

Now we need to load the data from the api using this model, so will send a get request to the api to fetch the current permissions. This can be easily achieved via a store query in the model hook of the admin/permissions/system-roles route. It is important to note here, that findAll is preferred over an empty query. To quote the source of this information,

The reason findAll is preferred over query when no filtering is done is, query will always make a server request. findAll on the other hand, will not make a server request if findAll has already been used once somewhere before. It’ll re-use the data already available whenever possible.

model() {
   return this.get('store').findAll('user-permission');
 }

The user permissions form is not a separate component and is directly embedded in the route template hence, there is no need to explicitly pass the model, it will be available in the route template by default. And can be used as following:

{{#each model as |userPermission|}}
<tr>
  <td>
    {{userPermission.name}}
    <div class="muted text">
      {{userPermission.description}}
    </div>
  </td>
  <td>
     {{ui-checkbox label=(t 'Unverified User') checked=userPermission.unverifiedUser onChange=(action (mut userPermission.unverifiedUser))}}
  </td>
  <td>
    {{ui-checkbox label=(t 'Anonymous User') checked=userPermission.anonymousUser onChange=(action (mut userPermission.anonymousUser))}}
  </td>
</tr>
{{/each}}

In the template after mutating the model’s values according to whether the checkboxes are checked or not, the only thing left is triggering the update action in the controller which will be triggered with the default submit action of the form.

updatePermissions() {
     this.set('isLoading', true);
     this.get('model').save()
       .then(() => {
         this.set('isLoading', false);
         this.notify.success(this.l10n.t('User permissions have been saved successfully.'));
       })
       .catch(()=> {
         this.set('isLoading', false);
         this.notify.error(this.l10n.t('An unexpected error has occurred. User permissions not saved.'));
       });
   }

The controller action first sets the isLoading property to true. This adds the semantic UI class loading to the the form,  and so the form goes in the loading state, to let the user know the request is being processed. Then the save()  call occurs and this makes a PATCH request to the API to update the values stored inside the database. And if the PATCH request is successful, the .then() clause executes, which in addition to setting the isLoading as false, notifies the user that the settings have been saved  successfully using the notify service.

However, in case there is an unexpected error and the PATCH request fails, the .catch() executes. After setting isLoading to false, it notifies the user of the error via an error notification.

Resources

 

 

Implementing Speakers Call API in Open Event Frontend

This article will illustrate how to display the speakers call details on the call for speakers page in the Open Event Frontend project using the Open Event Orga API. The API endpoints which will be mainly focussing on for fetching the speaker call details are:

GET /v1/speakers-calls/{speakers_call_id}

In the case of Open Event, the speakers are asked to submit their proposal beforehand if they are interested in giving some talk. For the same purpose, we have a section on the event’s website called as Call for Speakers on the event’s public page where the details about the speakers call are present along with the button Submit Proposal which redirects to the link where they can upload the proposal if the speakers call is open. Since the speakers call page is present on the event’s public page so the route which will be concerned with will be public/index route and its subroute public/index/cfs in the application. As the call for speakers details are nested within the events model so we need to first fetch the event and then from there we need to fetch the speaker-calls detail from the model.

The code to fetch the event model looks like this:

model(params) {
return this.store.findRecord('event', params.event_id, { include: 'social-links' });
}

The above model takes care of fetching all the data related to the event but, we can see that speakers call is not included as the parameter. The main reason behind this is the fact that the speakers is not required on each of the public route, rather it is required only for the subroute public/index/cfs route. Let’s see how the code for the speaker-call modal work to fetch the speaker calls detail from the above event model.  

model() {
    const eventDetails = this.modelFor('public');
    return RSVP.hash({
      event        : eventDetails,
      speakersCall : eventDetails.get('speakersCall')
    });
}

In the above code, we made the use of this.modelFor(‘public’) to make the use of the event data fetched in the model of the public route, eliminating the separate API call for the getting the event details in the speaker call route. Next, using the ember’s get method we are fetching the speakers call data from the eventDetails and placing it inside the speakersCall JSON object for using it lately to display speakers call details in public/index subroute.

Until now, we have fetched event details and speakers call details in speakers call subroute but we need to display this on the index page of the sub route. So we will pass the model from file cfs.hbs to call-for-speakers.hbs the code for which looks like this:

{{public/call-for-speakers speakersCall=model.speakersCall}}  

The trickiest part in implementing the speakers call is to check whether the speakers call is open or closed. The code which checks whether the call for speaker has to be open or closed is:

isOpen: computed('startsAt', 'endsAt', function() {
     return moment().isAfter(this.get('startsAt')) && moment().isBefore(this.get('endsAt'));
})

In the above-computed property isOpen of speakers-call model, we are passing the starting time and the ending time of the speakers call. We are then comparing if the starting time is after the current time and the current time is before the ending time than if both conditions satisfy to be true then the speakers call is open else it will be closed.  

Now, we need a template file where we will define how the user interface for call-for-speakers based on the above property, isOpen. The code for displaying UI based on its open or closed status is

  {{#if speakersCall.isOpen}}
    <a class="ui basic green label">{{t 'Open'}} </a>
    <div class="sub header">
      {{t 'Call for Speakers Open until'}} {{moment-format speakersCall.endsAt 'ddd, MMM DD HH:mm A'}}
    </div>
  {{else}}
    <a class="ui basic red label">{{t 'Closed'}}</a>
  {{/if}}

In the above code, we are checking is the speakersCall is open then we show a label open and display the date until which speakers call is opened using the moment helper in the format “ddd, MMM DD HH:mm A” else we show a label closed. The UI for the above code looks like this.

Fig. 1: The heading of speakers call page when the call for speakers is open

The complete UI of the page looks like this.

Fig. 2: The user interface for the speakers call page

The entire code for implementing the speakers call API can be seen here.

To conclude, this is how we efficiently fetched the speakers call details using the Open-Event-Orga speakers call API, ensuring that there is no unnecessary API call to fetch the data.  

Resources:

Adding JSON API support to ember-models-table in Open Event Front-end

Open Event Front-end project uses ember-models-table for handling all the table components in the application. Although ember-models-table is great for handling server requests for operations like pagination, sorting & filtering, but it does not support JSON API used in the Front-end project.

In this blog we will see how we integrated JSON API standards to ember-models-table. Lets see how we added support for JSON API to table and made requests to the Open Event Orga-server.

Adding JSON API support for filtering & sorting

The JSON API specs follow a strict structure for supporting meta data & filtering options, the server expects an array of objects for specifying the name of the field, operation and the value for filtering. The name attribute specifies the column for which we need to apply the filter. eg we use `name` for the events name in the. `op` attribute specifies the operation to be used for filtration, `val` attribute is used to provide a value for comparison. You can check the list of all the supported operations here.

For implementation of filter we will check if the column filter is being used i.e if the filter string is empty or not, if the string is not empty we add a filter object of the column using the specified specs, else we remove the filter object of the column.

if (filter) {
  query.filter.pushObject({
    name : filterTitle,
    op   : 'ilike',
    val  : `%${filter}%`
  });
} else {
  query.filter.removeObject({
    name : filterTitle,
    op   : 'ilike',
    val  : `%${filter}%`
  });
}

For sort functionally we need to pass a query parameter called `sort` which is a string value in the URL. Sorting can be done in ascending or descending order for which the server expects different values. We pass `sort=name` & `sort=-name` for sorting in ascending order & descending order respectively.

const sortSign = {
  none : '',
  asc  : '-',
  desc : ''
};
let sortedBy = get(column, 'sortedBy');
if (typeOf(sortedBy) === 'undefined') {
  sortedBy = get(column, 'propertyName');
}

Adding support for pagination

The pagination in JSON API is implemented using query parameters `page[size]` & `page[number]` which specify the size of the page & the current page number respectively eg

page[size]=10&page[number]=1

This will load the first ten events from the server in the application.

Once the data is loaded in the application we calculate the number of pages to be rendered. The response from the server has attached meta-data which contains the total number of the events in the following structure:

meta: {
  count: 100
}

We calculate the number of pages by dividing the total count by the size of the page. We check if the number of items is greater than the pageSize, and calculate the number of the pages using the formula `items / pagesize + (items % pagesize ? 1 : 0)`. If the items are less than the pageSize we do not have to calculate the pages and we simply hide the pagination in the footer.

if (pageSize > items) {
  this.$('.pagination').css({
    display: 'none'
  });
} else {
  this.$('.pagination').removeAttr('style');
  pages = parseInt((items / pageSize));
  if (items % pageSize) {
    pages = pages + 1;
  }
}

Adding dynamic routing support to ember-models-table

We may want to use the ember-models-table for dynamic routes like `events/list` route, where we load live, drafted & past events based on the current route. The ember-models-table by default do not support the dynamic routes. To add this we override the didReceiveAttrs() method of the component which is executed every time the component updates. We add reset the pageSize, currentPageNumber and the content of the table, as the routes change.

didReceiveAttrs() {
  set(this, 'pageSize', 10);
  set(this, 'currentPageNumber', 1);
  set(this, 'filteredContent', get(this, 'data'));
}

The result of this we now have tables supporting JSON API in the Open Event Front-end application

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

Resources