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Push Notification to delete local data

Power of PUSH

In this blog I will explain how you can use Push Notification to delete data saved in local SQLLite database.

What I'll explain :
  1. Simple MAF app, which will create a table and put some data in it while loading for the first time.
  2. It will have one page to display the data stored in the local database.
  3. I will configure MCS to send Push notification to the MAF app.
  4. On receive the MAF app will fire a delete statement to remove all the data form local database.
Requirements :
  1. MAF 2.2
  2. MCS or any push server
GitHub link : https://github.com/sohamda/PushAndDelete/
The basic architecture of this solution is :



Step #1 : Configure MCS Backend with Google Project ID and Prepare your MAF code

You need to create a Google project and enable messaging API. Then configure the MCS backend with the details. Then create your MAF application to register with MCS to receive push notifications.

Step #2 : Create table and add sample data while app loaded for the first time

Add a DB script to create a table and add some sample data, put the script inside ApplicationController > META-INF

initializedb.sql
PRAGMA auto_vacuum = FULL;
CREATE TABLE PUSH_AND_DEL (PAD_ID NUMBER(6) PRIMARY KEY, FIRST_NAME VARCHAR2(20), LAST_NAME VARCHAR2(25) NOT NULL);
INSERT INTO PUSH_AND_DEL (PAD_ID, FIRST_NAME, LAST_NAME) VALUES (100,'Natalie','Cole');
INSERT INTO PUSH_AND_DEL (PAD_ID, FIRST_NAME, LAST_NAME) VALUES (101,'Dean','Jones');
INSERT INTO PUSH_AND_DEL (PAD_ID, FIRST_NAME, LAST_NAME) VALUES (102,'Billy','Joe Royal');
INSERT INTO PUSH_AND_DEL (PAD_ID, FIRST_NAME, LAST_NAME) VALUES (103,'David','Bowie');


In LifeCycleListenerImpl.start() : try executing a select * query on the one of tables your app is/will be using, if it throws an SQLException create required tables and fill in with sample data.

For example : my app is using the table PUSH_AND_DEL. Also I have used "DBConnectionFactory" class, it is a custom class to initialize and create a connection. (detailed code is in the GitHub link)

try {
  Statement stat = DBConnectionFactory.getConnection().createStatement();
  ResultSet rs = stat.executeQuery("SELECT PAD_ID FROM PUSH_AND_DEL WHERE PAD_ID = -1;");
} catch (SQLException sqle) {
   try {
     initializeDatabaseFromScript();
   } catch (Exception e) {
     e.printStackTrace();
  }
}

initializeDatabaseFromScript() : Will initialize the DB, create table and put sample data in it. the snippet is as follows :

Connection conn = DBConnectionFactory.getConnection();

conn.setAutoCommit(false);

scriptStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("META-INF/initializedb.sql");
BufferedReader scriptReader = new BufferedReader(new InputStreamReader(scriptStream));
String nextLine;
StringBuffer nextStatement = new StringBuffer();

// The while loop iterates over all the lines in the SQL script,
// assembling them into valid SQL statements and executing them as
// a terminating semicolon is encountered
Statement stmt = conn.createStatement();
while ((nextLine = scriptReader.readLine()) != null) {
    if (nextLine.length() < 1) {
        continue;
    }
    nextStatement.append(nextLine);
    if (nextLine.endsWith(";")) {
        stmt.execute(nextStatement.toString());
        nextStatement = new StringBuffer();
    }
}


conn.commit();

 

Step #3 : Create a AMX page to display the data stored in the local DB

I have created one feature linked to an TaskFlow which has only one view associated with it to display the data stored in the local DB in a list view.




Step #4 : Update PushNotificationListener to delete data on receive of push message

Call the below snippet from PushNotificationListener.onMessage().

Connection conn = DBConnectionFactory.getConnection();
Statement stmt = conn.createStatement();
stmt.executeQuery("DELETE FROM PUSH_AND_DEL");
conn.commit();

You should add some extra logic to invoke the delete operation on receive of a special push message, i.e., some pre-defined text. Because your app should be able to distinguish between normal push message and delete push message.

The before and after receiving the push message, this is how it looks on my mobile 



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