Creating nested routes in Open event front end and navigating them with tabs via semantic UI – ember integration

Semantic UI is a modern development framework which helps build responsive and aesthetically beautiful layouts. While it is a really powerful framework in itself, it additionally offers seamless integrations with some of the other open source frameworks including ember js.

Open event front end is a project of fossasia organisation, which was created with the aim of decoupling the front end and the back end for the open event orga server. It is primarily based on ember JS and uses semantic UI for it’s UI.

Here we will be making a nested route /events/ with /events/live/, events/draft, events/past , events/import as it’s subroutes.

To get started with it, we simply use the ember CLI to generate the routes

$ ember generate route events

Then we go on to generate the successive sub routes as follows

$ ember generate route events/live
$ ember generate route events/past
$ ember generate route events/draft
$ ember generate route events/import

 

The router.js file should be looking like this now.

this.route('events', function() {
    this.route('live');
    this.route('draft');
    this.route('past');
    this.route('import');
  });

This means that our routes and sub routes are in place. Since we used the ember CLI to generate these routes, the template files for them would have generated automatically. Now these routes exist and we need to write the data in the templates of these routes which will get displayed to the end user.

Since the routes are nested, the content of the parent route can be made available to all the children routes via the outlet in ember js.

 

Next, we go to the template file of events/ route which is at templates/events.hbs And write the following code to create a menu and use ember integration of semantic UI link-to to link the tabs of the menu with the corresponding correct route. It will take care of selecting the appropriate data for the corresponding route and display it in the correct tab via the outlet

<.div class="row">
  <.div class="sixteen wide column">
    <.div class="ui fluid pointing secondary menu">
      {{#link-to 'events.live' class='item'}}
        {{t 'Live'}}
      {{/link-to}}
      {{#link-to 'events.draft' class='item'}}
        {{t 'Draft'}}
      {{/link-to}}
      {{#link-to 'events.past' class='item'}}
        {{t 'Past'}}
      {{/link-to}}
      {{#link-to 'events.import' class='item'}}
        {{t 'Import'}}
      {{/link-to}}
    <./div>
  <./div>
<./div>
<.div class="ui segment">
  {{outlet}}
<./div>

So finally, we start filling in the data for each of these routes. Let’s fill some dummy data at templates/events/live.hbs

<.div class="row">
  <.div class="sixteen wide column">
    <.table class="ui tablet stackable very basic table">
      <.thead>
        <.tr>
          <.th>{{t 'Name'}}<./th>
          <.th>{{t 'Date'}}<./th>
          <.th>{{t 'Roles'}}<./th>
          <.th>{{t 'Sessions'}}<./th>
          <.th>{{t 'Speakers'}}<./th>
          <.th>{{t 'Tickets'}}<./th>
          <.th>{{t 'Public URL'}}<./th>
          <.th><./th>
        <./tr>
      <./thead>
      <.tbody>
        <.tr>
          <.td>
            <.div class="ui header weight-400">
              <.img src="http://placehold.it/200x200" alt="Event logo" class="ui image">
              Sample Event
            <./div>
          <./td>
          <.td>
            March 18, 2016 - 09:30 AM
            <.br>(to)<.br>
            March 20, 2016 - 05:30 PM
          <./td>
          <.td>
            <.div class="ui ordered list">
              <.div class="item">[email protected] ({{t 'Organizer'}})<./div>
              <.div class="item">[email protected] ({{t 'Manager'}})<./div>
            <./div>
          <./td>
          <.td>
            <.div class="ui list">
              <.div class="item">{{t 'Drafts'}}: 0<./div>
              <.div class="item">{{t 'Submitted'}}: 0<./div>
              <.div class="item">{{t 'Accepted'}}: 0<./div>
              <.div class="item">{{t 'Confirmed'}}: 0<./div>
              <.div class="item">{{t 'Pending'}}: 0<./div>
              <.div class="item">{{t 'Rejected'}}: 0<./div>
            <./div>
          <./td>
          <.td>
            2
          <./td>
          <.td>
            <.div class="ui bulleted list">
              <.div class="item">{{t 'Premium'}} (12/100)<./div>
              <.div class="item">{{t 'VIP'}} (10/15)<./div>
              <.div class="item">{{t 'Normal'}} (100/200)<./div>
              <.div class="item">{{t 'Free'}} (100/500)<./div>
            <./div>
          <./td>
          <.td>
            <.div class="ui link list">
              <.a class="item" target="_blank" rel="noopener" href="http://nextgen.eventyay.com/e/ecc2001a">
                http://nextgen.eventyay.com/e/ecc2001a
              <./a>
            <./div>
          <./td>
          <.td class="center aligned">
            <.div class="ui vertical compact basic buttons">
              {{#ui-popup content=(t 'Edit event details') class='ui icon button'}}
                <.i class="edit icon"><./i>
              {{/ui-popup}}
              {{#ui-popup content=(t 'View event details') class='ui icon button'}}
                <.i class="unhide icon"><./i>
              {{/ui-popup}}
              {{#ui-popup content=(t 'Delete event') class='ui icon button'}}
                <.i class="trash outline icon"><./i>
              {{/ui-popup}}
            <./div>
          <./td>
        <./tr>
      <./tbody>
    <./table>
  <./div>
<./div>

           

Similarly we can fill the required data for each of the routes.And this is it, our nested route is ready. Here is a screenshot what you might expect.

Screenshot highlighting the tabs

Bottoms sheets in android

Hey Guys I recently used Bottom sheets, so that I should write a blog about it because I don’t see a lot of developers using this in their app UI’s.

It’s a very interesting UI element. A Bottom Sheet is a sheet of material that slides up from the bottom edge of the screen. Displayed only as a result of a user-initiated action, and can be swiped up to reveal additional content. It can be a temporary modal surface or a persistent structural element of an app.

This component was introduced in the Android Design Support library 23.2. Many apps like Google Maps use the bottom sheet, in which a sliding window pops up from the bottom of the screen. Also the Google play music app uses. When we drag up the sheet we see the song details as well as the current playlist.

Usage of expanded and collapsed Bottom sheets in Android

There are 3 states of Bottom sheets :-

  • Expanded — When the sheet is completely visible.
  • Collapsed — When the sheet is partially visible.
  • Hidden — When the sheet is completely hidden.

Step 1 is we need to import the latest design support library. Put this line in your app level build.gradle file.

compile ‘com.android.support:design:23.2.0’

Then one should create a new Blank Activity (not Empty Activity) in Android Studio. It sets up the CoordinatorLayout by default.

So now there ate two layouts created by default namely activity_main.xml and content_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="yet.best.bottomsheets.MainActivity"
tools:showIn="@layout/activity_main">

<Button
android:id="@+id/open"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_margin="5dp"
android:text="Open Bottom Sheet" />

<Button
android:id="@+id/collapse"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/open"
android:layout_centerHorizontal="true"
android:layout_margin="5dp"
android:text="Collapse Bottom Sheet" />

<Button
android:id="@+id/hide"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/collapse"
android:layout_centerHorizontal="true"
android:layout_margin="5dp"
android:text="Hide Bottom Sheet" />

</RelativeLayout>

Notice that 3 Buttons have been created in this layout to perform different actions with the bottom sheets.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="yet.best.bottomsheets.MainActivity">

<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">

<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

<include layout="@layout/content_main" />

<include
android:id="@+id/bottom_sheet"
layout="@layout/bottomsheet_main" />

<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="@dimen/fab_margin"
android:src="@android:drawable/ic_dialog_email"
app:layout_anchor="@id/bottom_sheet"
app:layout_anchorGravity="top|right|end" />

</android.support.design.widget.CoordinatorLayout>

Those who aren’t familiar with the coordinator layout — basically there is a base level layout activity_main which contains the FloatingButton and within this layout including content_main.xml which will contain the rest of the layout. Notice that one also has to include bottomsheet_main.xml. This layout contains our bottom sheet layout which will be created next.

Create a new layout file called bottomsheet_main.xml

bottomsheet_main.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="300dp"
android:background="#d3d3d3"
app:behavior_hideable="true"
app:behavior_peekHeight="70dp"
app:layout_behavior="@string/bottom_sheet_behavior">

<TextView
android:id="@+id/heading"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="7dp"
android:text="Collapsed"
android:textSize="18sp" />

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Main Content"
android:textSize="20sp" />

</RelativeLayout>

This layout is how our bottom sheet will actually look. You can design it as you want.

Now for the actual java code. This is the easiest part actually. Just set listeners to the 3 buttons created and perform the corresponding action with the bottom sheet.

public class MainActivity extends AppCompatActivity {

BottomSheetBehavior bottomSheetBehavior;
Button open, collapse, hide;
TextView heading;
@Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
  setSupportActionBar(toolbar);

View bottomSheet = findViewById(R.id.bottom_sheet);
  bottomSheetBehavior = BottomSheetBehavior.from(bottomSheet);

setup();
 }

private void setup() {
  open = (Button) findViewById(R.id.open);
  collapse = (Button) findViewById(R.id.collapse);
  hide = (Button) findViewById(R.id.hide);
  heading = (TextView) findViewById(R.id.heading);

//Handling movement of bottom sheets from buttons
  open.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    bottomSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
    heading.setText("Welcome");
    heading.setTextColor(ContextCompat.getColor(MainActivity.this, R.color.colorPrimary));
   }
  });

collapse.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
    heading.setText("Collapsed");
    heading.setTextColor(ContextCompat.getColor(MainActivity.this, R.color.colorAccent));
   }
  });

hide.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
   }
  });

//Handling movement of bottom sheets from sliding
  bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
   @Override
   public void onStateChanged(View bottomSheet, int newState) {
    if (newState == BottomSheetBehavior.STATE_COLLAPSED) {
     heading.setText("Collapsed");
     heading.setTextColor(ContextCompat.getColor(MainActivity.this, R.color.colorAccent));
    } else if (newState == BottomSheetBehavior.STATE_EXPANDED) {
     heading.setText("Welcome");
     heading.setTextColor(ContextCompat.getColor(MainActivity.this, R.color.colorPrimary));
    }
   }

@Override
   public void onSlide(View bottomSheet, float slideOffset) {}
  });
 }
}

We just use the bottomSheetBehavior.setState() method to set the relevant state on each button click.

The bottom sheets can also be dragged by touch gestures. One can simply touch the sheet and drag them up or down. For these touch gestures to be handled one has to implement the onStateChanged() listener. This listener is fired everytime the state of the sheet changes by gestures. Whenever this triggers it checks the state of the bottom sheet and again do the desired action which user would have done by the button clicks.

As you can see, this is a pretty neat UI solution and can be implemented so easily. Go try it out for yourself. Adios!

Working with ConstraintLayout in Android

Few months ago, during the Google I/O conference, Google introduced a new set of tools for Android developers. Among them is a new Layout editor and a new layout called the ConstraintLayout.

I’ll be highlighting the key points in this brand new layout.

ConstraintLayout is available in a new Support Library that’s compatible with Android 2.3 (Gingerbread) and higher, but the new layout editor is available only in Android Studio 2.2 Preview.

Layout Editor & Constraints Overview.

The new layout editor in Android Studio 2.2 Preview is specially built for the ConstraintLayout. You can specify the constraints manually, or automatically reference within the layout editor.

Overview of Constraints?

A constraint is the description of how a view should be positioned relative to other items, in a layout. A constraint is typically defined for one or more sides by connecting the view to:

  • An anchor point, or another view,
  • An edge of the layout,
  • Or An invisible guide line.

Since each view within the layout is defined by associations to other views within the layout, it’s easier to achieve flat hierarchy for complex layouts.

In principle, the ConstraintLayout works very similar to the RelativeLayout, but uses various handles (or say anchors) for the constraints.

  • Resize handle. The resize handle is the alt text seen in the corners of the figure above, and it’s used to resize the view.
  • Side handle. The side handle is the alt text in the figure above, and it’s used to specify the location of a widget. E.g using the left side handle to always be aligned to the right of another view, or the left of the ConstraintLayout itself.
  • Baseline handle. The baseline handle is the alt text in the figure above. It is used to align the text of a view by the baseline of the text on another view.

Getting started with ConstraintLayout

Setup

Ensure that you’re running the AS 2.2 preview, and Android Support Repository version 32 or higher, it’s required before you can use the ConstraintLayout. Let’s get started.

  • First, you need to add the constraint layout library to your app’s dependencies within your build.gradle file:
dependencies {
    compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha1'
}
  • Sync your project.

Add Constraints

There are typically two ways to create ConstraintLayout in AS. You can create a new XML layout and select the root element to be a ConstraintLayout or convert an existing layout into a ConstraintLayout as shown in the image below:

Once you have the ConstraintLayout setup, what is next is to add the constraints to the views within that layout.

As an example, drag an ImageView to the layout. The new layout builder will immediately ask to add a drawable or resource, select one from the options and press ok. Also drag a TextView unto the layout.

To create a constraint, drag the top side handle on the ImageView to the top of the ConstraintLayout. You can also drag from the top side handle of the TextView to the bottom handle of the ImageView

Using the Inspector Pane

Now that we’re able to add constraints, we will need to use the inspector. It’s on the right hand side of the layout builder and it lists various properties of the selected widget. Typically, it looks as shown below:

You can use the sliders to move the view by percentage along the x and y axes. You can also control the dimensions of the view from the inspector pane, by altering the values corresponding to the layout_width and layout_height fields.

Taking a closer look at the square widget on the inspector pane. It contains some more control over the dimensions of the views.

There are other modes of controlling the size of the view. Clicking on the inner lines in the image above help you cycle through the other modes.

  • Fixed mode: alt text This allows you specify the width and height of the view.
  • Any size: alt text This mode allows the image to fill up all the space required to fulfill that constraint. You can look at this like “match constraint”
  • Wrap content: alt text This just expands to fill the content of the view. E.g text or image

Using Auto-connect to add constraints.

Autoconnect as the name suggests, automatically creates connections between views/widgets. It tries to create connections to neighboring views/widgets.
To enable autoconnect, look out for the alt text icon on the top bar of the layout editor.

Thats’s almost it for the constraint layout.
If you want, you can head over to the official documentation on it at http://tools.android.com/tech-docs/layout-editor

Cheers.

Multiple Tickets: Back-end

In my previous post I talked about approach for Multiple Ticket feature’s user-interface [Link]. In this post I’ll discuss about Flask back-end used for saving multiple tickets.

HTML Fields Naming

Since the number of Tickets a user creates is unknown to the server, details of tickets were needed to be sent as an array of values. So the server would accept the list of values and iterate over them. To send data as an array the naming had to include brackets. Below are some input fields used in tickets:

<tr>
    <td>
        <input type="hidden" name="tickets[type]">
        <input type="text" name="tickets[name]" class="form-control" placeholder="Ticket Name" required="required" data-uniqueticket="true">
        <div class="help-block with-errors"></div>
    </td>
    <td>
        <input type="number" min="0" name="tickets[price]" class="form-control"  placeholder="$" value="">
    </td>
    <td>
        <input type="number" min="0" name="tickets[quantity]" class="form-control" placeholder="100" value="{{ quantity }}">
    </td>
    <!-- Other fields -->
</tr>

At the server

When the POST request reaches the server, any of the above fields (say tickets[name]) would be available as a list. The Flask Request object includes a form dictionary that contains all the POST parameters sent with the request. This dictionary is an ImmutableMultiDict object, which has a getlist method to get array of elements.

For instance in our case, we can get tickets[name] using:

@expose('/create', methods=('POST', 'GET'))
def create_view(self):
    if request.method == 'POST':
        ticket_names = request.form.getlist('tickets[name]')

    # other stuff

The ticket_names variable would contain the list of all the Ticket names sent with the request. So for example if the user created three tickets at the client-side, the form would possibly look like:

<form method="post">
  <!-- Ticket One -->
  <input type="text" name="tickets[name]" class="form-control" value="Ticket Name One">
  <!-- Ticket Two -->
  <input type="text" name="tickets[name]" class="form-control" value="Ticket Name Two">
  <!-- Ticket Three -->
  <input type="text" name="tickets[name]" class="form-control" value="Ticket Name Three">

</form>

After a successful POST request to the server, ticket_names should contain ['Ticket Name One', 'Ticket Name Two', 'Ticket Name Three'].

Other fields, like tickets[type], tickets[price], etc. can all be extracted from the Request object.

Checkbox Fields

A problem arose when a checkbox field was needed for every ticket. In my case, a “Hide Ticket” option was needed to let the user decide if he wants the ticket to be shown at the public Events page.

Screenshot from 2016-08-13 12:39:29

The problem with checkboxes is that, for a checkbox of a particular name attribute, if it is not selected, POST parameters of the request made by the client will not contain the checkbox input field parameter. So if I define an input field as a checkbox with the following naming convention, and make a POST request to the server, the server will receive blah[] parameter only if the input element had been checked.

<input type="checkbox" name="blah[]" >

This creates a problem for “Hide ticket” checkboxes. For instance, at the client-side the user creates three tickets with the first and last tickets having their checkboxes selected, the server would get an array of two.

<form>
  <!-- Ticket One -->
  <input type="checkbox" name="tickets[hide]" checked>
  <!-- Ticket Two -->
  <input type="checkbox" name="tickets[hide]">
  <!-- Ticket Three -->
  <input type="checkbox" name="tickets[hide]" checked>

</form>
ticket_hide_opts = request.form.getlist('tickets[hide]')

ticket_hide_opts would be an array of length two. And there is no way to tell what ticket had its “Hide ticket” option checked. So for the hide checkbox field I had to define input elements with unique names to extract them at the server.

There is also a hack to overcome the unchecked-checkbox problem. It is by using a hidden field with the same name as the checkbox. You can read about it here: http://www.alexandrejoseph.com/blog/2015-03-03-flask-unchecked-checkbox-value.html.

Multiple Tickets: User Interface

An Event can have multiple tickets for different purposes. For instance an Arts Exhibition can have multiple Galleries. The Organizer might be interested in assigning a ticket (let’s assume paid) for each Gallery. The user can then buy tickets for the Galleries that he wishes to attend. The feature that Multiple Tickets really provide is exclusiveness. Let’s say Gallery1 has a shorter area (by land) than others. Obviously the Organizer would want fewer people to be present there than other Galleries. To do this, he can create a separate ticket for Gallery1 and specify a shorter sales period. He can also reduce the Maximum number of order that a user can make (max_order). If we would have implemented single ticket per event, this wouldn’t have been possible.

Tickets at Wizard

To handle multiple tickets at the wizard, proper naming of input tags was required. Since the number of tickets that can be created by the user was unknown to the server we had to send ticket field values as lists. Also at the client-side a way was required to let users create multiple tickets.

User Interface

A ticket can be of three types: Free, Paid and Donation. Out of these, only the Paid tickets need a Price. The Tickets holder could be a simple table, with every ticket being a table row. This became more complex afterwards, when more details about the ticket needed to be displayed. A ticket would then be two table rows with one of them (details) hidden.

Ticket holder can be a simple bootstrap table:

<table class="table tickets-table">
    <thead>
        <tr>
            <th>Ticket Name</th>
            <th>Price</th>
            <th>Quantity</th>
            <th>Options</th>
        </tr>
    </thead>
    <tbody>
      <!-- Ticket -->
      <tr>
        <!-- Main info -->
      </tr>
      <tr>
        <!-- More details (initially hidden) -->
      </tr>
      <!-- /Ticket -->
    </tbody>
</table>

To make ticket creation interactive, three buttons were needed to create the above three tickets. The type-name doesn’t not necessarily have to be shown to the user. It could be specified with the Price. For Paid ticket, the Price input element would be a number. For Free and Donation tickets, a Price input element wasn’t required. We could specify an element displaying one of the two types: Free or Donation.

Here’s the holder table with a Free Ticket and a Donation Ticket:

Screenshot from 2016-08-09 16:51:06

Since only the Price field is changing in the three types of tickets, I decided to create a template ticket outside of the form and create a JavaScript function to create one of the tickets by cloning the template.

A Free Ticket with its edit options opened up. You can see other details about the ticket in the second table row.

Screenshot from 2016-08-09 16:52:14

This is a simplified version of the template. I’ve removed common bootstrap elements (grid system) including some other fields.

<div id="ticket-template">
<tr>
    <td>
        <input type="hidden" name="tickets[type]">
        <input type="text" name="tickets[name]" class="form-control" placeholder="Ticket Name" required="required" data-uniqueticket="true">
        <div class="help-block with-errors"></div>
    </td>
    <td>
        <!-- Ticket Price -->
    </td>
    <td>
        <input type="number" min="0" name="tickets[quantity]" class="form-control" placeholder="100" value="{{ quantity }}">
    </td>
    <td>
        <div class="btn-group">
            <a class="btn btn-info edit-ticket-button" data-toggle="tooltip" title="Settings">
                <i class="glyphicon glyphicon-cog"></i>
            </a>
            <a class="btn btn-info remove-ticket-button" data-toggle="tooltip" title="Remove">
                <i class="glyphicon glyphicon-trash"></i>
            </a>
        </div>
    </td>
</tr>
<tr>
    <td colspan="4">
        <div class="row" style="display: none;">
            <!-- Other fields including Description, Sales Start and End time,
              Min and Max Orders, etc.
            -->
        </div>
    </td>
</tr>
</div>

Like I said, the Price element of ticket will make the type obvious for the user, so a type field does not need to be displayed. But the type field is required by the server. You can see it specified as hidden in the template.

The function to create a Ticket according to the type:

I’ve commented snippets to make it easy to understand.

function createTicket(type) {
    /* Clone ticket from template */
    var $tmpl = $("#ticket-template").children().clone();

    var $ticket = $($tmpl[0]).attr("id", "ticket_" + String(ticketsCount));
    var $ticketMore = $($tmpl[1]).attr("id", "ticket-more_" + String(ticketsCount));

    /* Bind datepicker and timepicker to dates and times */
    $ticketMore.find("input.date").datepicker();
    $ticketMore.find("input.time").timepicker({
        'showDuration': true,
        'timeFormat': 'H:i',
        'scrollDefault': 'now'
    });

    /* Bind iCheck to checkboxes */
    $ticketMore.find("input.checkbox.flat").iCheck({
        checkboxClass: 'icheckbox_flat-green',
        radioClass: 'iradio_flat-green'
    });

    /* Bind events to Edit (settings) and Remove buttons */
    var $ticketEdit = $ticket.find(".edit-ticket-button");
    $ticketEdit.tooltip();
    $ticketEdit.on("click", function () {
        $ticketMore.toggle("slow");
        $ticketMore.children().children(".row").slideToggle("slow");
    });

    var $ticketRemove = $ticket.find(".remove-ticket-button");
    $ticketRemove.tooltip();
    $ticketRemove.on("click", function () {
        var confirmRemove = confirm("Are you sure you want to remove the Ticket?");
        if (confirmRemove) {
            $ticket.remove();
            $ticketMore.remove();
        }
    });

    /* Set Ticket Type field */
    $ticket.children("td:nth-child(1)").children().first().val(type);

    /* Set Ticket Price field */
    var html = null;
    if (type === "free") {
        html = '';
    } else if (type === "paid") {
        html = '';
    } else if (type === "donation") {
        html = '';
    }
    $ticket.children("td:nth-child(2)").html(html);

    /* Append ticket to table */
    $ticket.hide();
    $ticketMore.children().children(".row").hide();
    $ticketsTable.append($ticket, $ticketMore);
    $ticket.show("slow");

    ticketsCount += 1;
  }

The flow is simple. Clone the template, bind events to various elements, specify type and price fields and then append to the ticket holder table.

Screenshot from 2016-08-09 17:00:59

We use the Datepicker and Timepicker JavaScript libraries for date and time elements. So fields using these widgets need to have methods called on the elements. Also, we use iCheck for checkboxes and radio buttons. Apart from these, the Edit-Ticket and Remove-Ticket buttons also need event handlers. Edit-Ticket button toggles the Ticket Details segment (second tr of a ticket). Remove-Ticket deletes the ticket. After the Price and Type fields are set, the ticket is appended to the holder table with slow animation.

Building interactive elements with HTML and javascript: Interact.js + resizing

{ Repost from my personal blog @ https://blog.codezero.xyz/building-interactive-elements-with-html-and-javascript-interact-js-resizing/ }

In a few of the past blog posts, we saw about implementing resizing with HTML and javascript. The functionality was pretty basic with simple resizing. In the last blog post we saw about interact.js.

interact.js is a lightweight, standalone JavaScript module for handling single-pointer and multi-touch drags and gestures with powerful features including inertia and snapping.

Getting started with Interact.js

You have multiple option to include the library in your project.

  • You can use bower to install (bower install interact) (or)
  • npm (npm install interact.js) (or)
  • You could directly include the library from a CDN (https://cdnjs.cloudflare.com/ajax/libs/interact.js/1.2.6/interact.min.js).
Implementing resizing

Let’s create a simple box using HTML. We’ll add a class called resizable to it so that we can reference it to initialize Interact.js

<div class="resizable">  
    Use right/bottom edge to resize
</div>

We need to create an interact instance. Once the instance is created, we have to call the resizable method on it to add resize support to the div.

interact('.resizable')
  .resizable({
    edges: { right: true, bottom: true }
  })
  .on('resizemove', function (event) {
    

  });

Inside the resizable method, we can pass configuration options. The edgesconfig key allows us to specify on which all edges, resizing should be allowed. Right now, we have allowed on the right and bottom edges. Similarly we can have resizing support in the top and left edges too.

The resizemove event is triggered by interact every time the user tries to resize the div. From the event, we can get the box that is being resized, (i.e) the target by accessing event.target.

The event object also provides us event.rect.width and event.rect.height which is the width and height of the div after resizing. We’ll not set this as the width of the div so that, the user is able to see the width change.

var target = event.target;
    // update the element's style
    target.style.width  = event.rect.width + 'px';
    target.style.height = event.rect.height + 'px';

We can also instruct Interact.js to preserve the aspect ratio of the box by adding an option preserveAspectRatio: true to the configuration object passed to resizable method during initialization.

JavaScript
interact('.resizable')
  .resizable({
    edges: { right: true, bottom: true }
  })
  .on('resizemove', function (event) {
    var target = event.target;

    // update the element's style
    target.style.width  = event.rect.width + 'px';
    target.style.height = event.rect.height + 'px';
  });

Resizing and drag-drop (with Interact.js) were used to create the Scheduler tool at Open Event. The tool allows event/track organizers to easily arrange the sessions into their respective rooms by drag-drop and also to easily change the timings of the events by resizing the event block. The entire source code of the scheduler can be viewed at app/static/js/admin/event/scheduler.js in the Open Event Organizer server’s GitHub repository.

Demo:
https://jsfiddle.net/xdfocdty/

Creating Dynamic Footer with Popover

In Open-Event Webapp generator, the track page height varies according to the popover that appears on hovering the tracks. The problem with this design was the footer of the page that always remains static and produce a bad UI to user.

12

So, I have decided to make footer dynamic so that it varies it’s position according to the popover appeared on hover. The approach was a bit tricky but the diagram below will make it easy to understand.

Dynamic footer

The following code will work on hovering the track.

//popover.js 

var outerContheight= $('.main').offset().top + $('.main').outerHeight();
var tracknext= $(track).next();
var tracktocheck= track.offset().top + track.outerHeight() + 
 tracknext.outerHeight() + 15;
 var shift= tracktocheck - outerContheight;
 if(shift > 0){
 
 $('.footer').css({
 'position':'absolute',
 'top': outerContheight + shift,
 'width':'100%',
 'z-index': '999'
 })
 }

If shift > 0 which is calculated as shown in the above code it means that the footer needs to be shifted and hence we shift the footer by setting absolute position in CSS. Else we set position: static for footer.

 $('.footer').css({
 'position':'static'
 })

After following the above approach the footer position changes according to the popover. Here is the screencast for the approach.

 

User Notifications

The requirement for a notification area came up when I was implementing Event-Role invites feature. For not-existing users that were not registered in our system, an email with a modified sign-up link was sent. So just after the user signs up, he will be accepted as that particular role. Now for users that were already registered to our platform a dedicated area was needed to let the user know that he has been invited to be a role at an event. Similar areas were needed for Session invites, Call for papers, etc. To take care of these we thought of implementing a separate notifications area for the user, where such messages could be sent to registered users. Issue

Base Model

I kept base db model for a user notification very basic. It had a user field that would be a Foreign key to a User class object. title and message would contain the actual data that the user would read. message can contain HTML tags, so if someone wants to display the notification with some markup he could store that in the message. The user might also want to know when a notification was received. The received_at field stores a datetime object for the same purpose.

There is also has_read field that was later added. It stores a boolean value that tells if the user has marked the notification as Read.

class Notification(db.Model):
    """
    Model for storing user notifications.
    """

    id = db.Column(db.Integer, primary_key=True)

    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    user = db.relationship('User', backref='notifications')

    title = db.Column(db.String)
    message = db.Column(db.Text)
    action = db.Column(db.String)
    received_at = db.Column(db.DateTime)
    has_read = db.Column(db.Boolean)

    def __init__(self,
                 user,
                 title,
                 message,
                 action,
                 received_at,
                 has_read=False):
        self.user = user
        self.title = title
        self.message = message
        self.action = action
        self.received_at = received_at
        self.has_read = has_read

action field helps the Admin identify the notification. Like if it is a message for Session Schedule change or an Event-Role invite. When a notification is logged, the administrator could tell what exactly the message is for.

Unread Notification Count

The user must be informed if he has received a notification. This info must be available at every page so he doesn’t have to switch over to the notification area to check for new ones. A notification icon at the navbar perhaps.

Screenshot from 2016-07-19 02:00:47

The data about this notification count had to be available at the navbar template at every page. I decided to define it as a method in the User class. This way it could be displayed using the User object. So if the user was authenticated, the icon with the notification count could be displayed.

class User(db.Model):
    """User model class
    """
    # other stuff
    
    def get_unread_notif_count(self):
        return len(Notification.query.filter_by(user=self,
                                                has_read=False).all())
{% if current_user.is_authenticated %}
    <!-- other stuff -->

    <li>
             <a class="info-number" href="{{ url_for('profile.notifications_view') }}">
                  <i class="fa fa-envelope-o"></i>
                  <span class="badge bg-green">{{ current_user.get_unread_notif_count() | default('', true) }}</span>
             </a>
    </li>

    <!-- other stuff -->

{% endif %}

If the count is zero, count number is not displayed.

Possible Enhancement

The notification count comes with the HTML generated by the template at the server. So to check for new notifications the user must either refresh the page or travel to another page. To show newly received notifications without refreshing the page the WebSocket API can be used. I’ve it in my bucket list and I’ll implement it soon.

Building interactive elements with HTML and javascript: Interact.js + drag-drop

{ Repost from my personal blog @ https://blog.codezero.xyz/building-interactive-elements-with-html-and-javascript-interact-js-drag-drop }

In a few of the past blog posts, we saw about implementing drag-drop andresizing with HTML and javascript. The functionality was pretty basic with a simple drag-and-drop and resizing. That is where, a javascript library called as interact.js comes in.

interact.js is a lightweight, standalone JavaScript module for handling single-pointer and multi-touch drags and gestures with powerful features including inertia and snapping.

With Interact.js, building interactive elements is like a eating a piece of your favorite cake – that easy !

Getting started with Interact.js

You have multiple option to include the library in your project.

  • You can use bower to install (bower install interact) (or)
  • npm (npm install interact.js) (or)
  • You could directly include the library from a CDN (https://cdnjs.cloudflare.com/ajax/libs/interact.js/1.2.6/interact.min.js).

Implementing a simple draggable

Let’s start with some basic markup. We’ll be using the draggable class to enable interact.js on this element.

<div id="box-one" class="draggable">  
  <p> I am the first Box </p>
</div>  
<div id="box-two" class="draggable">  
    <p> I am the second Box </p>
</div>

The first step in using interact.js is to create an interact instance. Which you can create by using interact('<the selector>'). Once the instance is created, you’ll have to call the draggable method on it to enable drag. Draggable accepts a javascript object with some configuration options and some pretty useful callbacks.

// target elements with the "draggable" class
interact('.draggable')  
  .draggable({
    // enable inertial throwing
    inertia: true,
    // keep the element within the area of it's parent
    restrict: {
      restriction: "parent",
      endOnly: true,
      elementRect: { top: 0, left: 0, bottom: 1, right: 1 }
    },
    // enable autoScroll
    autoScroll: true,
    // call this function on every dragmove event
    onmove: dragMoveListener,
  });

  function dragMoveListener (event) {
    var target = event.target,
        // keep the dragged position in the data-x/data-y attributes
        x = (parseFloat(target.getAttribute('data-x')) || 0) + event.dx,
        y = (parseFloat(target.getAttribute('data-y')) || 0) + event.dy;

    // translate the element
    target.style.webkitTransform =
    target.style.transform =
      'translate(' + x + 'px, ' + y + 'px)';

    // update the posiion attributes
    target.setAttribute('data-x', x);
    target.setAttribute('data-y', y);
  }

Here we use the onmove event to move the box according to the dx and dyprovided by interact when the element is dragged.

Implementing a simple drag-drop

Now to the above draggable, we’ll add a drop zone into which the two draggable boxes can be dropped.

<div id="dropzone" class="dropzone">You can drop the boxes here</div>

Similar to a draggable, we first create an interact instance. Then we call the dropzone method on to tell interact that, that div is to be considered as a dropzone. The dropzone method accepts a json object with configuration options and callbacks.

// enable draggables to be dropped into this
interact('.dropzone').dropzone({  
  // Require a 50% element overlap for a drop to be possible
  overlap: 0.50,

  // listen for drop related events:

  ondropactivate: function (event) {
    // add active dropzone feedback
    event.target.classList.add('drop-active');
  },
  ondragenter: function (event) {
    var draggableElement = event.relatedTarget,
        dropzoneElement = event.target;

    // feedback the possibility of a drop
    dropzoneElement.classList.add('drop-target');
  },
  ondragleave: function (event) {
    // remove the drop feedback style
    event.target.classList.remove('drop-target');
  },
  ondrop: function (event) {
    event.relatedTarget.textContent = 'Dropped';
  },
  ondropdeactivate: function (event) {
    // remove active dropzone feedback
    event.target.classList.remove('drop-active');
    event.target.classList.remove('drop-target');
  }
});

Each event provides two important properties. relatedTarget which gives us the DOM object of the draggable that is being dragged. And target which gives us the DOM object of the dropzone. We can use this to provide visual feedback for the user when he/she is dragging.

Demo:

https://jsfiddle.net/niranjan94/yqwc4hqz/2/

Optimization with SASS

The problem with using CSS is that it can become repetitive when used in large projects. Like using same values of margins, paddings, radius. SASS provides a way to store these values in ONE variable and to use that variable instead.

SASS provides various concepts that optimize CSS. Like discussed above using variables for all the color names and fonts will remove the repetition. A piece of code from Open-Event-Webapp is shown below for declaring variable names.

//config.scss

@charset "UTF-8";
 
// Colors
$black: #000;
$white: #fff;
$red: #e2061c;
$gray-light: #c9c8c8;
$gray: #838282;
$gray-dark: #777;
$gray-extra-dark: #757575;
$gray-extra-light:#e7e7e7 !default;
$gray-perfect :#ddd;
$blue: #253652;
$orange: #e12b00;
$vivid-blue: #2196F3;
$pure-orange: #ff8700;
$light-purple: #ebccd1;
$red-dark: #e52d27;
$light-black: #333333;
$light-skyblue : #b7cdff !default;
$gray-trackshade: #999;
$blue-shade: #2482d3;
$dark-black: rgba(22, 22, 22, 0.99) !default;
$black-main:#232323 !default;
$timeroom-color:rgba(0,0,0,.10) !default;
$session-color: $gray-trackshade !default;
$header-color: #f8f8f8 !default;
$main-background: #fff !default;

// Corp-Colors
$corp-color: $white !default;
$corp-color-dark: darken($corp-color, 15%) !default;
$corp-color-second: $red !default;
$corp-color-second-dark: darken($corp-color-second, 15%) !default;

Nesting

SASS supports nesting concept. The nested SCSS changes to CSS when compiled. A good approach follows nesting elements to three-degree maximum.

// Nesting in application.scss session-list (Open-Event-Webapp)

.session{

  &-list {

    li{
     cursor: pointer;
      }
   .label {
     background: #ff8700;
     border-color: $light-purple;
     color: #FFFFFF;
     font-weight: 500;
     font-size: 80%;
     margin-left: -8px;
    }
   .session-title {
      margin-top: 0.1em;
       .session-link {
         font-size: 12px;
        }
    }
 }
 &-location{
 text-align: left;
 }

}

The output generated after compilation will be

//Code from schedule.css in Open-event-webapp

.session-list li {
 cursor: pointer; 
}

.session-list .label {
 background: #ff8700;
 border-color: #ebccd1;
 color: #FFFFFF;
 font-weight: 500;
 font-size: 80%;
 margin-left: -8px; 
}

.session-list .session-title {
 margin-top: 0.1em; 
}

 .session-list .session-title .session-link {
 font-size: 12px;
 }

.session-location {
 text-align: left; 
}

Mixins

Mixins are another way to optimize the SASS code. Mixins are just like functions that let us pass the values as parameters to make the code more flexible.

// Simple mixin for button
@mixin btn($color, $width, $height) {
 display: block;
 font: 16px “Open sans”, arial;
 color: $color;
 width: $width;
 height: $height;
}

Using these type of simple approaches make CSS more effective and efficient. It will enhance the workflow and help us to write cleaner code.