As we are progressing in our Phimpme Android app. I added account manager part which deals with connecting all other accounts to phimpme. Showing a list of connected accounts.

We need a persistent storage to store all the details such as username, full name, profile image url, access token (to access API). I researched on various Object Relation mapping (ORMs) such as:

1. DBFlow: https://github.com/Raizlabs/DBFlow
2. GreenDAO: https://github.com/greenrobot/greenDAO
3. SugarORM: http://satyan.github.io/sugar/
4. Requery: https://github.com/requery/requery

and other NoSQL databases such as Realm Database : https://github.com/realm/realm-java.

After reading a lot from some blogs on the benchmarking of these ORMs and database, I came to know that Realm database is quite better in terms of Speed of writing data and ease of use.

Steps to integrate Realm Database:

• Installation of Realm database in android

Following these steps https://realm.io/docs/java/latest/#installation quickly setup realm in android. Add

classpath "io.realm:realm-gradle-plugin:3.3.2"

in Project level build.gradle file and Add

apply plugin: 'realm-android' 

in app level build.gradle, That’s it for using Realm

• Generating required Realm models

Firstly, make sure what you need to store in your database. In case of phimpme, I first go through the account section and noted down what needs to be there.  Profile image URL, username, full name, account indicator image name. Below image illustrate this better.

This is the Realm Model class I made in Kotlin to store name, username and access token for accessing API.

open class AccountDatabase(
       @PrimaryKey var name: String = "",
       var username: String = "",
       var token: String = ""
) : RealmObject()

• Writing data in database

In Account manager, I create a add account option from where a dialog appear with a list of accounts. Currently, Twitter is working, when onSuccess function invoke in AccountPickerFragment I start a twitter session and store values in database. Writing data in database:

// Begin realm transaction
realm.beginTransaction();

// Creating Realm object for AccountDatabase Class
account = realm.createObject(AccountDatabase.class,
       accountsList[0]);

account.setUsername(session.getUserName());
account.setToken(String.valueOf(session.getAuthToken()));
realm.commitTransaction();

Begin and commit block in necessary. There is one more way of doing this is using execute function in Realm

• Use Separate Database Helper class for Database operations

It’s good to use a separate class for all the Database operations needed in the project. I created a DatabaseHelper Class and added a function to query the result needed. Query the database

public RealmResults<AccountDatabase> fetchAccountDetails(){
   return realm.where(AccountDatabase.class).findAll();
}

It give all of the results, stored in the database like below

• Problems I faced with annotation processor while using Kotlin and Realm together

The Kotlin annotation processor not running due to the plugins wrong order. This issue https://github.com/realm/realm-java/pull/2568 helped me in solving that. I addded apply plugin: ‘kotlin-kapt’. In app gradle file and shift apply plugin: ‘realm-android’ In below the order.

Resources:

• Realm for Android (official): https://news.realm.io/news/realm-for-android/
• Write in Realm Database: https://realm.io/docs/java/latest/#writes
• Queries in Realm Database: https://realm.io/docs/java/latest/#queries
• A detailed Blog post on Realm Database: https://medium.com/@Zhuinden/how-to-use-realm-for-android-like-a-champ-and-how-to-tell-if-youre-doing-it-wrong-ac4f66b7f149