Skill Editor in SUSI Skill CMS

SUSI Skill CMS is a web application built on ReactJS framework for creating and editing SUSI skills easily. It follows an API centric approach where the SUSI Server acts as an API server. In this blogpost we will see how to add a component which can be used to create a new skill SUSI Skill CMS.

For creating any skill in SUSI we need four parameters i.e model, group, language, skill name. So we need to ask these 4 parameters from the user. For input purposes we have a common card component which has dropdowns for selecting models, groups and languages, and a text field for skill name input.

<SelectField
    floatingLabelText="Model"
    value={this.state.modelValue}
    onChange={this.handleModelChange}
>
    {models}
</SelectField>
<SelectField
    floatingLabelText="Group"
    value={this.state.groupValue}
    onChange={this.handleGroupChange}
>
    {groups}
</SelectField>
<SelectField
    floatingLabelText="Language"
    value={this.state.languageValue}
    onChange={this.handleLanguageChange}
>
    {languages}
</SelectField>
<TextField
    floatingLabelText="Enter Skill name"
    floatingLabelFixed={true}
    hintText="My SUSI Skill"
    onChange={this.handleExpertChange}
/>
<RaisedButton label="Save" backgroundColor="#4285f4" labelColor="#fff" style={{marginLeft:10}} onTouchTap={this.saveClick} />

This is the card component where we get the user input. We have API endpoints on SUSI Server for getting the list of models, groups and languages. Using those APIs we inflate the dropdowns.
Then the user needs to edit the skill. For editing of skills we have used Ace Editor. Ace is an code
editor written in pure javascript. It matches the features native editors like Sublime and TextMate.

To use Ace we need to install the component.

npm install react-ace --save                        

This command will install the dependency and update the package.json file in our project with this dependency.

To use this editor we need to import AceEditor and place it in the render function of our react class.

<AceEditor
    mode=" markup"
    theme={this.state.editorTheme}
    width="100%"
    fontSize={this.state.fontSizeCode}
    height= "400px"
    value={this.state.code}
    name="skill_code_editor"
    onChange={this.onChange}
    editorProps={{$blockScrolling: true}}
/>

Now we have a page that looks something like this

Now we need to handle the click event when a user clicks on the save button.

First we check if the user is logged in or not. For this we check if we have the required cookies and the access token of the user.

 if(!cookies.get('loggedIn')) {
            notification.open({
                message: 'Not logged In',
                description: 'Please login and then try to create/edit a skill',
                icon: <Icon type="close-circle" style={{ color: '#f44336' }} />,
            });
            return 0;
        }

If the user is not logged in then we show him a error notification and asks him to login.

Then we check if he has filled all the required fields like name of the skill etc. and after that we call an API Endpoint on SUSI Server that will finally store the skill in the skill_data_repo.

let url= “http://api.susi.ai/cms/modifySkill.json”
$.ajax({
    url:url,
    dataType: 'jsonp',
    jsonp: 'callback',
    crossDomain: true,
    success: function (data) {
        console.log(data);
        if(data.accepted===true){
            notification.open({
                message: 'Accepted',
                description: 'Your Skill has been uploaded to the server',
                icon: <Icon type="check-circle" style={{ color: '#00C853' }} />,
            });
           }
    }
});

In the success function of ajax call we check if accepted parameter is true from the server or not. If accepted is true then we show user a notification with a message that “Your Skill has been uploaded to the server”.

To see this component running please visit http://skills.susi.ai/skillEditor.

Resources

Material-UI: http://www.material-ui.com/

Ace Editor: https://github.com/securingsincity/react-ace

Ajax: http://api.jquery.com/jquery.ajax/

Universal Cookies: https://www.npmjs.com/package/universal-cookie

Zooming Feature in the Phimpme Android’s Camera

The Phimpme Android application comes with a complete package of camera, Edit images, sharing and gallery functionalities. It has a well featured and fully functional camera with all the capabilities that a user expects from a camera application. One such feature in the Phimpme Android application is the zooming functionality. It provides the user the option to zoom in using the pinch gesture of the fingers or the user can select the settings to zoom in from the volume buttons. In this tutorial, I will be explaining how I achieved the zooming functionality in the Phimpme Android app.

Step 1

The first thing we need to do is to check whether the device will support the zoom in functionality or not to avoid random crashes while runtime of the application and while performing the zoom action in case the camera of the device doesn’t support this feature. This can be done by the following lines of code:

Camera.Parameters params = mCamera.getParameters();
Boolean supports = params.isZoomSupported();

Step 2

Now after getting the camera parameters and checking whether the camera supports the zoom in functionality, we need to add the touch listener to the surface view of the camera so that we can get the touch locations and the finger spacing of the user to get the pinch to zoom in functionality. This can be done using the following line of code.

surfaceView.setOnTouchListener(this);

Whenever the user touches the screen this touch listener gives a callback to the overridden onTouchEvent method and passes the MotionEvent to the function. The motion event object in Android handles the movement reports. Now in the onTouchEvent method, we calculate the finger spacing between the two fingers and calculate the approximate amount by which the user wants to zoom in. The finger spacing can be calculated using the following lines of code.

float x = event.getX(0) - event.getX(1);
   float y = event.getY(0) - event.getY(1);
   return FloatMath.sqrt(x * x + y * y);

After getting the finger spacing we need to cancel the auto focus of the camera before performing the zoom action so that the application does not crash. This can be achieved by a single line of code below.

mCamera.cancelAutoFocus();

Step 3

The final step is to set the zoom level in the camera application by calculating the zoom level by using the finger spacing. For this, first we need to get the max zoom level supported by the device so that we do not apply the zoom level that is not supported by the device. The calculation of max zoom level and setting of the desired zoom level by the user can be performed by using the following lines of code.

int maxZoom = params.getMaxZoom();
   int zoom = params.getZoom();
   float newDist = getFingerSpacing(event);
   if (newDist > mDist) {
       //zoom in
       if (zoom < maxZoom)
           zoom++;
   } else if (newDist < mDist) {
       //zoom out
       if (zoom > 0)
           zoom--;
   }
   mDist = newDist;
   params.setZoom(zoom);

This is how we have achieved the functionality of zooming in and clicking pictures in the Phimpme Android application. To get the full source code and to know how to use the volume control buttons to zoom in/out, please refer to the Phimpme Android repository.

Resources

  1. GitHub – Open camera source code : https://github.com/almalence/OpenCamera
  2. Android developer’s guide – MotionEvents in Android : https://developer.android.com/reference/android/view/MotionEvent.html
  3. StackOverflow – Pinch to zoom functionality : https://stackoverflow.com/questions/8120753/android-camera-preview-zoom-using-double-finger-touch
  4. GitHub – Phimpme Android repository : https://github.com/fossasia/phimpme-android

Dynamic Segments in Open Event Frontend

In the Open Event Frontend project we have a page where we show all types of events. We have classified events into six classes like live, draft, past etc. Now each event type should have it’s own page describing it. What should we do now? Make six different routes corresponding to each class of event? Isn’t that too cumbersome. Is there any other method to do it?

Dynamic segment is the answer to the above question. Dynamic segment is that segment of the path for a route that will change based on content of  the page. Dynamic segments are frequently used in Open Event Frontend.

One such use is in /admin/events. Here we have button for different categories of events. We do not make separate routes for each of them, instead we use dynamic segments. We’ll have a single route and we will change the data in the route corresponding to the tab chosen.

Lets now add dynamic segments to /admin/events. First of all we’ll add the following code snippet in router.js.

this.route(‘events’, function() {
     this.route(‘list’, { path: ‘/:events_status’ });
     this.route(‘import’);
   });

Here : signifies the presence of dynamic segment and it is followed by an identifier. It’s the identifier by which the route matches the corresponding model to show.

Now as our route would show data depending upon the tab selected, we must change the title of page depending upon the same. For this we add the following code snippet in admin/events/list.js. Here we set the title of the page using titleToken() function and access the dynamic portion of url using params.events_status

export default Route.extend({
 titleToken() {
   switch (this.get(‘params.events_status’)) {
     case ‘live’:
       return this.l10n.t(‘Live’);
     case ‘draft’:
       return this.l10n.t(‘Draft’);
     case ‘past’:
       return this.l10n.t(‘Past’);
     case ‘deleted’:
       return this.l10n.t(‘Deleted’);
   }
 },
 model(params) {
   this.set(‘params’, params);
   return [{
   // Events data
   }];
 }
});

We’ll now link the tabs template/admin/events to the corresponding models using Link-to the helper.Here we have linked ‘Live’, ‘Draft’, ‘Past’, ‘Deleted’ buttons to dynamic segments. Let’s understand how it works.Let’s take example of Live button.Live button is linked to admin/events/list and this list is replaced by ‘live’. So our final route becomes admin/events/live.

<div class=“ui grid stackable”>
 <div class=“row”>
   <div class=“sixteen wide column”>
     {{#tabbed-navigation isNonPointing=true}}
       {{#link-to ‘admin.events.index’ class=’item’}}
         {{t ‘All Events’}}
       {{/link-to}}
       {{#link-to ‘admin.events.list’ ‘live’ class=’item’}}
         {{t ‘All Live’}}
       {{/link-to}}
       {{#link-to ‘admin.events.list’ ‘draft’ class=’item’}}
         {{t ‘All Draft’}}
       {{/link-to}}
       {{#link-to ‘admin.events.list’ ‘past’ class=’item’}}
         {{t ‘All Past’}}
       {{/link-to}}
       {{#link-to ‘admin.events.list’ ‘deleted’ class=’item’}}
         {{t ‘All Deleted’}}
       {{/link-to}}
       {{#link-to ‘admin.events.import’ class=’item’}}
         {{t ‘Import’}}
       {{/link-to}}
     {{/tabbed-navigation}}
   </div>
 </div>
 <div class=“row”>
   {{outlet}}
 </div>
</div>

Additional Resources

Using Dynamic segments to Reduce Code Redundancy of Recurring HTML in Open Event ember Frontend

While developing web apps, at times we require the same HTML for different pages in our app. This leads to redundancy and low code-reusability. This can be well managed in ember.js by using dynamic segments in our routes.

In Open Event Front-end we have a route named /sessions where we want to show the details of the event’s sessions and we want to categorize the sessions in all, pending, accepted, confirmed and rejected sessions hence want to create the following subroutes under it.

events/<event-id>/sessions
events/<event-id>/sessions/pending
events/<event-id>/sessions/accepted
events/<event-id>/sessions/confirmed
events/<event-id>/sessions/rejected

All of these subroutes show different data based on the routes in a table with exactly same fields. So if we use dynamic segments, we can decrease code redundancy and increase code reusability. So let us see how to add these subroutes as dynamic segments.

Firstly, we have to add a dynamic part (pending, accepted, confirmed, rejected) under our URL /sessions . For this, edit the following code snippet to the router.js file. In place of list write the name of route handler which handles our subroutes and in place of session_status write any identifier you want as session_status is the dynamic part which changes according to subroutes. In our case it will be pending, accepted, confirmed or rejected.

     this.route('sessions', function() {
        this.route('list', { path: '/:session_status' });
      });

To display all the sessions in our /sessions route, we have to edit index route handler and return data from model hook. Now when we hit  /sessions end point, the template which we are using redundantly, i.e. list.hbs, gets data from a model hook of this route handler.

Next we need to define a model hook in our list.js file which returns data for the dynamic routes. In list.js, we would want to change the title of our page according to the dynamic segments. These dynamic segments are available under model hook in this route under param parameter. We are using this.set which sets the provided key or path to the value. Make this available in titleToken function and by applying simple switch case, we can change the title dynamically.

Till now, we could access our dynamic segments by manually changing the URL. Let’s add a link to do this transition automatically for us. For this, we edit our session.hbs file and provide links using a linkto helper. One thing to take care here is that we should pass the dynamic segments along with the link-to helper.

{{#link-to 'events.view.sessions.list' 'pending' class='item'}}

Here, pending is the dynamic segment which we are passing to our route handler. Similarly, we can make the links for all our dynamic segments. Also in this template, we should provide outlets for the common template i.e list.hbs which will be reused by other dynamic subroutes. And finally, we define our reusable template in list.hbs file.

Now when we hit on different links we are redirected to different routes which are using different data but same templates. Also, we can see this transition in our URL and title.

To know more about dynamic segments refer to Ember guide.

Adding Global Search and Extending Bookmark Views in Open Event Android

When we design an application it is essential that the design and feature set enables the user to find all relevant information she or he is looking for. In the first versions of the Open Event Android App it was difficult to find the Sessions and Speakers related to a certain Track. It was only possible to search for them individually. The user also could not view bookmarks on the Main Page but had to go to a separate tab to view them. These were some capabilities I wanted to add to the app.

In this post I will outline the concepts and advantages of a Global Search and a Home Screen in the app. I took inspiration from the Google I/O 2017 App  that had these features already. And, I am demonstrating how I added a Home Screen which also enabled users to view their bookmarks on the Home Screen itself.

Global Search v/s Local Search

Local Search
Global Search

 

 

 

 

 

 

 

 

 

If we observe clearly in the above images we can see there exists a stark difference in the capabilities of each search.
See how in the Local Search we are just able to search within the Tracks section and not anything else.
This is fixed in the Global Search page which exists along with the new home screen.
As all the results that a user might need are obtained from a single search, it improves the overall user-experience of the app. Also a noticeable feature that was missing in the current iteration of the application was that a user had to go to a separate tab to view his/her bookmarks. It would be better for the app to have a home page detailing all the Event’s/Conference’s details as well as display user bookmarks on the homepage.

New Home

Home screen
Home screen with Bookmarks

 

 

 

 

 

 

 

 

 

Home screen with Bookmarks               
Home screen Demo

 

 

 

 

 

 

 

 

 

The above posted images/gifs indicate the functioning and the UI/UX of the new Homescreen within the app.
Currently I am working to further improve the way the Bookmarks are displayed.
The new home screen provides the user with the event details i.e FOSSASIA 2017 in this case. This would be different for each conference/event and the data is fetched from the open-event-orga server(the first part of the project) if it doesn’t already exist in the JSON files provided in the assets folder of the application. All the event information is being populated by the JSON files provided in the assets folder in the app directory structure.

  • config.json
  • sponsors.json
  • microlocations.json
  • event.json(this stores the information that we see on the home screen)
  • sessions.json
  • speakers.json
  • track.json

All the file names are descriptive enough to denote what do all of them store.I hope that I have put forward why the addition of a New Home with Bookmarks along with the Global Search feature was a neat addition to the app.

Link to PR for this feature : https://github.com/fossasia/open-event-android/pull/1565

Resources

 

 

Accepting Stripe payments on behalf of a third-party

{ Repost from my personal blog @ https://blog.codezero.xyz/accepting-stripe-payments-on-behalf-of-a-third-party }

In Open Event, we allow the organizer of each event to link their Stripe account, so that all ticket payments go directly into their account. To make it simpler for the organizer to setup the link, we have a Connect with stripe button on the event creation form.

Clicking on the button, the organizer is greeted with a signup flow similar to Login with Facebook or any other social login. Through this process, we’re able to securely and easily obtain the credentials required to accept payments on behalf of the organizer.

For this very purpose, stripe provides us with an OAuth interface called as Stripe Connect. Stripe Connect allows us to connect and interact with other stripe accounts through an API.

We’ll be using Python’s requests library for making all the HTTP Requests to the API.
You will be needing a stripe account for this.

Registering your platform
The OAuth Flow

The OAuth flow is similar to most platforms.

  • The user is redirected to an authorization page where they login to their stripe account and authorize your app to access their account
  • The user is then redirected back to a callback URL with an Authorization code
  • The server makes a request to the Token API with the Authorization code to retrieve the access_token, refresh_token and other credentials.

Implementing the flow

Redirect the user to the Authorization URL.
https://connect.stripe.com/oauth/authorize?response_type=code&client_id=ca_8x1ebxrl8eOwOSqRTVLUJkWtcfP92YJE&scope=read_write&redirect_uri=http://localhost/stripe/callback  

The authorization url accepts the following parameters.

  1. client_id – The client ID acquired when registering your platform.required.
  2. response_type – Response type. The value is always code. required.
  3. redirect_uri – The URL to redirect the customer to after authorization.
  4. scope – Can be read_write or read_only. The default is read_only. For analytics purposes, read_only is appropriate; To perform charges on behalf of the connected user, We will need to request read_write scope instead.

The user will be taken to stripe authorization page, where the user can login to an existing account or create a new account without breaking the flow. Once the user has authorized the application, he/she is taken back to the Callback URL with the result.

Requesting the access token with the authorization code

The user is redirected back to the callback URL.

If the authorization failed, the callback URL has a query string parameter error with the error name and a parameter error_description with the description of the error.

If the authorization was a success, the callback URL has the authorization code in the code query string parameter.

import requests

data = {  
    'client_secret': 'CLIENT_SECRET',
    'code': 'AUTHORIZATION_CODE',
    'grant_type': 'authorization_code'
}

response = requests.post('https://connect.stripe.com/oauth/token', data=data)

The client_secret is also obtained when registering your platform. The codeparameter is the authorization code.

On making this request, a json response will be returned.

If the request was a success, the following response will be obtained.

{
  "token_type": "bearer",
  "stripe_publishable_key": PUBLISHABLE_KEY,
  "scope": "read_write",
  "livemode": false,
  "stripe_user_id": USER_ID,
  "refresh_token": REFRESH_TOKEN,
  "access_token": ACCESS_TOKEN
}

If the request failed for some reason, an error will be returned.

{
  "error": "invalid_grant",
  "error_description": "Authorization code does not exist: AUTHORIZATION_CODE"
}

The access_token token obtained can be used as the secret key to accept payments like discussed in Integrating Stripe in the Flask web framework.

Writing your first Dockerfile

In this tutorial, I will show you how to write your first Dockerfile. I got to learn Docker because I had to implement a Docker deployment for our GSoC project Open Event Server.

First up, what is Docker ? Basically saying, Docker is an open platform for people to build, ship and run applications anytime and anywhere. Using Docker, your app will be able to run on any platform that supports Docker. And the best part is, it will run in the same way on different platforms i.e. no cross-platform issues. So you build your app for the platform you are most comfortable with and then deploy it anywhere. This is the fundamental advantage of Docker and why it was created.

So let’s start our dive into Docker.

Docker works using Dockerfile (example), a file which specifies how Docker is supposed to build your application. It contains the steps Docker is supposed to follow to package your app. Once that is done, you can send this packaged app to anyone and they can run it on their system with no problems.

Let’s start with the project structure. You will have to keep Dockerfile at the root of your project. A basic project will look as follows –

- app.py
- Dockerfile
- requirements.txt
- some_app_folder/
-   some_file
-   some_file

Dockerfile starts with a base image that decides on which image your app should be built upon. Basically “Images” are nothing but apps. So for example you want your run your application in Ubuntu 14.04 VM, you use ubuntu:14.04 as the base image.

FROM ubuntu:14.04
MAINTAINER Your Name <[email protected]>

These are usually the first two lines of a Dockerfile and they specify the base image and Dockerfile maintainer respectively. You can look into Docker Hub for more base images.

Now that we have started our Dockerfile, it’s time to do something. Now think, if you are trying to run your app on a new system of Ubuntu, what will be the first step you will do… You update the package lists.

RUN apt-get update

You may possibly want to update the packages too.

RUN apt-get update
RUN apt-get upgrade -y

Let’s explain what’s happening. RUN is a Docker command which instructs to run something on the shell. Here we are running apt-get update followed by apt-get upgrade -y on the shell. There is no need for sudo as Docker already runs commands with root user previledges.

The next thing you will want to do now is to put your application inside the container (your Ubuntu VM). COPY command is just for that.

RUN mkdir -p /myapp
WORKDIR /myapp
COPY . .

Right now we were at the root of the ubuntu instance i.e. in parallel with /var, /home, /root etc. You surely don’t want to copy your files there. So we create a ‘myapp’ directory and set it as WORKDIR (project’s directory). From now on, all commands will run inside it.

Now that copying the app has been done, you may want to install it’s requirements.

RUN apt-get install -y python python-setuptools python-pip
RUN pip install -r requirements.txt

You might be thinking why am I installing Python here. Isn’t it present by default !? Well let me tell you that base image ‘ubuntu’ is not the Ubuntu you are used with. It just contains the bare essentials, not stuff like python, gcc, ruby etc. So you will have to install it on your own.

Similarly if you are installing some Python package that requires gcc, it will not work. When you are struck in a issue like that, try googling the error message and most likely you will find an answer. :grinning:

The last thing remaining now is to run your app. With this, your Dockerfile is complete.

CMD python app.py

Building the app

To build the app run the following command.

docker build -t myapp .

Then to run the app, execute docker run myapp.

Where to go next

Refer to the official Dockerfile reference to learn more Dockerfile commands. Also you may find my post on using Travis to test Docker applications interesting if you want to automate testing of your Docker application.

I will write more blog posts on Docker as I learn more. I hope you found this one useful.

 

{{ Repost from my personal blog http://aviaryan.in/blog/gsoc/dockerfile-basic.html }}

PayPal Express Checkout in Python

As per the PayPal documentation …

Express Checkout is a fast, easy way for buyers to pay with PayPal. Express Checkout eliminates one of the major causes of checkout abandonment by giving buyers all the transaction details at once, including order details, shipping options, insurance choices, and tax totals.

The basic steps for using express checkout to receive one-time payments are:

  1. Getting the PayPal API credentials.
  2. Making a request to the API with the transaction details to get a token
  3. Using the token to send the users to the PayPal payment page
  4. Capturing the payment and charging the user after the user completes the payment at PayPal.

We will be using PayPal’s Classic NVP (Name-value pair) API for implementing this.

Getting PayPal API Credentials

To begin with, we’ll need API Credentials.
We’ll be using the Signature API credentials which consists of

  • API Username
  • API Password
  • Signature

To obtain these, you can follow the steps at Creating and managing NVP/SOAP API credentials – PayPal Developer.

You’ll be getting two sets of credentials. Sandbox and Live. We’ll just stick to the Sandbox for now.

Now, we need sandbox test accounts for making and receiving payments. Head over to Creating Sandbox Test Accounts – PayPal Developer and create two sandbox test accounts. One would be the facilitator and one would be the buyer.

PayPal NVP Servers

All the API actions will take place by making a request to the PayPal server. PayPal has 4 different NVP servers for 4 different purposes.

  1. https://api-3t.sandbox.paypal.com/nvp – Sandbox “testing” server for use with API signature credentials.
  2. https://api-3t.paypal.com/nvp– PayPal “live” production server for use with API signature credentials.
  3. https://api.sandbox.paypal.com/nvp – Sandbox “testing” server for use with API certificate credentials.
  4. https://api.paypal.com/nvp – PayPal “live” production server for use with API certificate credentials.

We’ll be using the Sandbox “testing” server for use with API signature credentials.

Creating a transaction and obtaining the token

To create a transaction, we’ll need to make a request with all the transaction details. We can use Python requests library to easily make the requests. All requests are POST.

We’ll be calling the SetExpressCheckout method of the NVP API to obtain the token.

import requests  
import urlparse

data = {  
    'USER': credentials['USER'],
    'PWD': credentials['PWD'],
    'SIGNATURE': credentials['SIGNATURE'],
    'SUBJECT': credentials['FACILITATOR_EMAIL'],
    'METHOD': 'SetExpressCheckout',
    'VERSION': 93,
    'PAYMENTREQUEST_0_PAYMENTACTION': 'SALE',
    'PAYMENTREQUEST_0_AMT': 100,
    'PAYMENTREQUEST_0_CURRENCYCODE': 'USD',
    'RETURNURL': 'http://localhost:5000/paypal/return/',
    'CANCELURL': 'http://localhost:5000/paypal/cancel/'
}
response = requests.post('https://api-3t.sandbox.paypal.com/nvp', data=data)  
token = dict(urlparse.parse_qsl(response.text))['TOKEN']

Here,

  • USER represents your Sandbox API Username.
  • PWD represents your Sanbox API Password.
  • SIGNATURE represents your Sandbox Signature.
  • SUBJECT represents the facilitator’s email ID.
  • PAYMENTREQUEST_0_AMT is the total transaction amount.
  • PAYMENTREQUEST_0_CURRENCYCODE is the 3 digit ISO 4217 Currency code.
  • RETURNURL is where the user will be sent to after the transaction
  • CANCELURL is where the user will be sent to if he/she cancels the transaction.

A URL-Encoded, Name-value pair response would be obtained. We can decode that into a dict by using Python’s urlparse modules.

From the response, we’re extracting the TOKEN which we will use to generate the payment URL for the user.

This token has to be retained since we’ll be using it in further steps of the process.

Redirecting the user to PayPal for Approval

With the token we obtained, we can form the payment URL.

https://www.sandbox.paypal.com/cgi-bin/webscr?cmd=_express-checkout&token=<TOKEN>

We’ll have to send the user to that URL. Once the user completes the transaction at PayPal, he/she will be returned to the RETURNURL where we’ll further process the transaction.

Obtaining approved payment details and capturing the payment

Once the user completes the transaction and gets redirected back to RETURNURL, we’ll have to obtain the confirmed payment details from PayPal. For that we can again use the token ID that we obtained before.

We’ll now be making a request to the GetExpressCheckoutDetails method of the API.

import requests  
import urlparse

data = {  
    'USER': credentials['USER'],
    'PWD': credentials['PWD'],
    'SIGNATURE': credentials['SIGNATURE'],
    'SUBJECT': credentials['FACILITATOR_EMAIL'],
    'METHOD': 'GetExpressCheckoutDetails',
    'VERSION': 93,
    'TOKEN': TOKEN
}

response = requests.post('https://api-3t.sandbox.paypal.com/nvp', data=data)  
result = dict(urlparse.parse_qsl(response.text))  
payerID = result['PAYERID']

A URL-Encoded, Name-value pair response would be obtained. We can decode that into a dict by using Python’s urlparse modules.

This will provide us with information about the transaction such as transaction time, transaction amount, charges, transaction mode, etc.

But, we’re more interested in the PAYERID which we’ll need to capture/collect the payment. The money is not transferred to the facilitators account until it is captured/collected. So, be sure to collect it.

To collect it, we’ll be making another request to the DoExpressCheckoutPaymentmethod of the API using the token and the PAYERID.

import requests  
import urlparse

data = {  
    'USER': credentials['USER'],
    'PWD': credentials['PWD'],
    'SIGNATURE': credentials['SIGNATURE'],
    'SUBJECT': credentials['FACILITATOR_EMAIL'],
    'METHOD': 'DoExpressCheckoutPayment',
    'VERSION': 93,
    'TOKEN': TOKEN,
    'PAYERID': payerID,
    'PAYMENTREQUEST_0_PAYMENTACTION': 'SALE',
    'PAYMENTREQUEST_0_AMT': 100,
    'PAYMENTREQUEST_0_CURRENCYCODE': 'USD',
}

response = requests.post('https://api-3t.sandbox.paypal.com/nvp', data=data)  
result = dict(urlparse.parse_qsl(response.text))  
status = result['ACK']

All the details have to be the same as the ones provided while obtaining the token. Once we make the request, we’ll again get a URL-Encoded, Name-value pair response. We can decode that into a dict by using Python’s urlparsemodules.

From the response, ACK (Acknowledgement status) will provide us with the status of the payment.

  • Success — A successful operation.
  • SuccessWithWarning — A successful operation; however, there are messages returned in the response that you should examine.
  • Failure — The operation failed; the response also contains one or more error messages explaining the failure.
  • FailureWithWarning — The operation failed and there are messages returned in the response that you should examine.

And, we have completed the PayPal transaction flow for Express Checkout. These are just the basics and might miss a few stuff. I suggest you go through the following links too for a better understanding of everything:

For Reference:
  1. PayPal Name-Value Pair API Basics – PayPal Developer
  2. How to Create One-Time Payments Using Express Checkout – PayPal Developer

Creating a Widget for your Android App

Having a widget for your app, not only helps it to stand out among its alternatives but also provides user information on the go without having to open the app. Keeping this thought in mind, I decided to make a widget for my GSoC project. Let’s go through the steps involved.

Step 1:

Creating a new widget from Android Studio.

Open up your project for which you need a widget and navigate to the project’s Java source. Create a new sub-package there named widget. Right click on the newly created sub-package and select the New->Widget option from there.

new_widget

Follow the instructions on the next screen.

screenshot-area-2016-07-30-002554
Most of the fields here are pretty much self explanatory. After doing this and running the app in your device, you will be able to see a widget for your app in the widget picker.
Screenshot_20160730-003515_01

 

Just kidding, this was the easy part, off to more harder things now!

Step 2:

Populating the widget with data.

Now, there can be 2 broad type of widgets Information Widgets and Collection Widgets.

Information widgets are simple widgets that are used to display an information that changes with time, for example Weather Widget or a Clock Widget.

Whereas, collection widgets are widgets which display a collection of data, for example the GMail widget is a collection widget.
These are relatively complex and harder than the Information Widgets.

In this post, we will focus on making a Collection Widget.

For Collection widgets, we need two layout files, one for the widget and one for each item in the widget collection.

Go ahead and create the two layout files. The wizard automatically generates the widget_layout.xml for you, you just need to edit it up.

stock_layout.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:id="@+id/widget_toolbar"
        android:layout_height="?android:attr/actionBarSize"
        android:background="@color/colorPrimary">

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:src="@drawable/stock_up"
            android:contentDescription="@string/stock_widget" />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:src="@drawable/stock_down"
            android:contentDescription="@string/stock_widget" />

        <TextView
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_marginStart="32dp"
            android:gravity="center_vertical"
            android:text="@string/your_stocks"
            android:textAppearance="@android:style/TextAppearance.DeviceDefault.Widget.ActionBar.Title"
            android:layout_marginLeft="32dp" />
    </LinearLayout>

    <ListView
        android:id="@+id/widget_listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/backGround"></ListView>

</LinearLayout>
list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="72dp"
    android:gravity="center_vertical"
    android:orientation="horizontal"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    >
  <TextView
      android:id="@+id/stock_symbol"
      style="@style/StockSymbolTextStyle"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:gravity="start|center_vertical"
      tools:text="List Item"
      />
</LinearLayout>

Next up, having a look at the modified files, we can see that the Widget creation wizard added some stuff into out AndroidManifest.xml and created a new java file.

Upon taking a closer look at the manifest, we can see that the widget’s java class has been registered as a <receiver/>

Next, opening up the NewAppWidget.java, we will see that it extends AppWidgetProvider and some methods are already overridden for you.

Time to edit up this file to reference to the layouts we have just created.

import android.annotation.TargetApi;
import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.support.annotation.NonNull;
import android.widget.RemoteViews;

/**
 * Implementation of App Widget functionality.
 */
public class StockWidgetProvider extends AppWidgetProvider {

    private static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                                        int appWidgetId) {
        // Construct the RemoteViews object which defines the view of out widget
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
        // Instruct the widget manager to update the widget
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            setRemoteAdapter(context, views);
        } else {
            setRemoteAdapterV11(context, views);
        }
        /** PendingIntent to launch the MainActivity when the widget was clicked **/
        Intent launchMain = new Intent(context, MainActivity.class);
        PendingIntent pendingMainIntent = PendingIntent.getActivity(context, 0, launchMain, 0);
        views.setOnClickPendingIntent(R.id.widget, pendingMainIntent);
        appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId,R.id.widget_listView);
        appWidgetManager.updateAppWidget(appWidgetId, views);
    }

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // There may be multiple widgets active, so update all of them
        for (int appWidgetId : appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId);
        }

        super.onUpdate(context, appWidgetManager, appWidgetIds);
    }

    @Override
    public void onEnabled(Context context) {
        // Enter relevant functionality for when the first widget is created
    }

    @Override
    public void onDisabled(Context context) {
        // Enter relevant functionality for when the last widget is disabled
    }

  /** Set the Adapter for out widget **/

    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    private static void setRemoteAdapter(Context context, @NonNull final RemoteViews views) {
        views.setRemoteAdapter(R.id.widget_listView,
                new Intent(context, StockWidgetService.class));
    }

    
    /** Deprecated method, don't create this if you are not planning to support devices below 4.0 **/
    @SuppressWarnings("deprecation")
    private static void setRemoteAdapterV11(Context context, @NonNull final RemoteViews views) {
        views.setRemoteAdapter(0, R.id.widget_listView,
                new Intent(context, StockWidgetService.class));
    }

}

Now, create a WidgetDataProvider which will provide us with data to be displayed inside the widget.

You can use a static data for now (like a prefilled ArrayList, but make sure that this data should be dynamic for making the widget meaningful)

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.os.Binder;
import android.widget.RemoteViews;
import android.widget.RemoteViewsService;

/**
 * Created by the-dagger on 24/7/16.
 */

public class WidgetDataProvider implements RemoteViewsService.RemoteViewsFactory {

    private Context context;
    private Cursor cursor;
    private Intent intent;

    //For obtaining the activity's context and intent
    public WidgetDataProvider(Context context, Intent intent) {
        this.context = context;
        this.intent = intent;
    }

    private void initCursor(){
        if (cursor != null) {
            cursor.close();
        }
        final long identityToken = Binder.clearCallingIdentity();    
        /**This is done because the widget runs as a separate thread 
        when compared to the current app and hence the app's data won't be accessible to it
        because I'm using a content provided **/
        cursor = context.getContentResolver().query(QuoteProvider.Quotes.CONTENT_URI,
                new String[]{QuoteColumns._ID, QuoteColumns.SYMBOL, QuoteColumns.BIDPRICE,
                        QuoteColumns.PERCENT_CHANGE, QuoteColumns.CHANGE, QuoteColumns.ISUP},
                QuoteColumns.ISCURRENT + " = ?",
                new String[]{"1"},null);
        Binder.restoreCallingIdentity(identityToken);
    }

    @Override
    public void onCreate() {
        initCursor();
        if (cursor != null) {
            cursor.moveToFirst();
        }
    }

    @Override
    public void onDataSetChanged() {
        /** Listen for data changes and initialize the cursor again **/
        initCursor();
    }

    @Override
    public void onDestroy() {
    cursor.close();
    }

    @Override
    public int getCount() {
        return cursor.getCount();
    }

    @Override
    public RemoteViews getViewAt(int i) {
        /** Populate your widget's single list item **/
        RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.list_item_quote);
        cursor.moveToPosition(i);
        remoteViews.setTextViewText(R.id.stock_symbol,cursor.getString(cursor.getColumnIndex(QuoteColumns.SYMBOL)));
        remoteViews.setTextViewText(R.id.bid_price,cursor.getString(cursor.getColumnIndex(QuoteColumns.BIDPRICE)));
        remoteViews.setTextViewText(R.id.change,cursor.getString(cursor.getColumnIndex(QuoteColumns.CHANGE)));
        if (cursor.getString(cursor.getColumnIndex(QuoteColumns.ISUP)).equals("1")) {
            remoteViews.setInt(R.id.change, "setBackgroundResource", R.drawable.percent_change_pill_green);
        } else {
            remoteViews.setInt(R.id.change, "setBackgroundResource", R.drawable.percent_change_pill_red);
        }
        return remoteViews;
    }

    @Override
    public RemoteViews getLoadingView() {
        return null;
    }

    @Override
    public int getViewTypeCount() {
        return 1;
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public boolean hasStableIds() {
        return true;
    }
}

Let’s also create a service that invokes the WidgetDataProvider after a fixed interval

import android.content.Intent;
import android.widget.RemoteViewsService;

/**
 * Created by the-dagger on 24/7/16.
 */

public class StockWidgetService extends RemoteViewsService {
    @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new WidgetDataProvider(this,intent);
    }
}

Phew.. almost done with this now.

Finally edit up the widget_info.xml located inside /res/values/xml/ of your project.

Edit it to reference the time after which your widget will be updated, the preview image which should show up in the widget picker and minimum width and height of the widget.

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:initialKeyguardLayout="@layout/app_widget"
    android:initialLayout="@layout/app_widget"
    android:minHeight="110dp"
    android:minWidth="170dp"
    android:previewImage="@drawable/example_appwidget_preview"
    android:resizeMode="horizontal|vertical"
    android:updatePeriodMillis="86400000"
    android:widgetCategory="home_screen"></appwidget-provider>

Well, once this is done, go ahead and fire up your app. You will be able to see the newly created and updated widget in your homescreen.

 widget

Pretty awesome right!
Congratulations on making your first widget.

For now the app only opens a specific activity on clicking it, but you can read up a bit on how to execute a separate task on clicking each item on the list by using a pendingIntent.

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/