Realm is a mobile database that is meant to replace SQLite. It provides a simpler interface than SQLite and supports features like encryption, auto-updating, and cross-platform support between Android, iOS, and other platforms. Models are defined by creating classes that extend RealmObject. Objects can then be queried, created, updated, and deleted directly from Realm. Relationships between objects are also supported.

1. DJ RAUSCH
ANDROID ENGINEER @ MOKRIYA
DJRAUSCH.COM
REALM

2. REALM - A MOBILE DATABASE REPLACEMENT
PHOENIX MOBILE FESTIVAL
▸Use #phxmobi as the twitter hashtag and follow
@phxmobifestival for updates.
▸Download Phoenix Mobile Festival App (search for
'phxmobi') from AppStore or Google Play. From the app you
can create your own agenda for the day and provide
feedback on the sessions.

3. REALM - A MOBILE DATABASE REPLACEMENT
WHO AM I?
▸Android Developer at Mokriya.
▸Developing Android apps since the start (first Android phone
was the Droid)
▸Before working at Mokriya, worked for Jaybird, and a few
smaller companies
▸Self published a few apps - Spotilarm, Volume Sync, Bill
Tracker

4. REALM - A MOBILE DATABASE REPLACEMENT
WHAT IS REALM?
▸It’s a database.
▸A replacement for Sqlite.
▸It is NOT an ORM for Sqlite.

5. REALM - A MOBILE DATABASE REPLACEMENT
WHY SHOULD I USE IT?
▸Easy Setup
▸Cross Platform
▸ Android, iOS (Objective-C and Swift), Xamarin, React Native
▸FAST

6. REALM - A MOBILE DATABASE REPLACEMENT
WHO IS USING REALM?

7. REALM - A MOBILE DATABASE REPLACEMENT
FEATURES OF REALM
▸Fluent Interface
▸Field Annotations
▸Migrations
▸Encryption
▸Auto Updates and Notifications
▸RxJava Support

8. REALM - A MOBILE DATABASE REPLACEMENT
FLUENT INTERFACE
getRealm().where(Bill.class)
.equalTo("deleted", false)
.between("dueDate", new
DateTime().minusWeeks(1).toDate(), new
DateTime().plusWeeks(1).plusDays(1)
.toDate())
.findAll();
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/util/BillUtil.jav
a#L46

9. REALM - A MOBILE DATABASE REPLACEMENT
FIELD ANNOTATIONS
▸@PrimaryKey
▸Table PK
▸@Required
▸Require a value, not null
▸@Ignore
▸Do not persist field to disk

10. REALM - A MOBILE DATABASE REPLACEMENT
MIGRATIONS
public class Migration implements RealmMigration {
@Override
public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
RealmSchema schema = realm.getSchema();
if (oldVersion == 0) {
//Add pay url to bill
schema.get("Bill")
.addField("payUrl", String.class);
oldVersion++;
}…
}
}
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/models/Migration.java

11. REALM - A MOBILE DATABASE REPLACEMENT
ENCRYPTION
RealmConfiguration config = new
RealmConfiguration.Builder(context)
.encryptionKey(getKey())
.build();
Realm realm = Realm.getInstance(config);
https://realm.io/docs/java/latest/#encryption

12. REALM - A MOBILE DATABASE REPLACEMENT
AUTO UPDATES & NOTIFICATIONS
bills.addChangeListener(new RealmChangeListener<RealmResults<Bill>>() {
@Override
public void onChange(RealmResults<Bill> element) {
if (adapter.getItemCount() == 0) {
noBillsLayout.setVisibility(View.VISIBLE);
recyclerView.setVisibility(View.GONE);
} else {
noBillsLayout.setVisibility(View.GONE);
recyclerView.setVisibility(View.VISIBLE);
}
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/MainActivity.java#L132

13. REALM - A MOBILE DATABASE REPLACEMENT
RXJAVA
getRealm().where(Bill.class).contains(“uuid”, billUuid).findFirst().asObservable()
.filter(new Func1<Bill, Boolean>() {
@Override
public Boolean call(Bill bill) {
return bill.isLoaded();
}
}).subscribe(new Action1<Bill>() {
@Override
public void call(Bill bill) {
setUI(bill);
if (bill.paidDates != null) {
if (adapter == null) {
adapter = new PaidDateRecyclerViewAdapter(ViewBillDetails.this, bill.getPaidDates());
recyclerView.setLayoutManager(new LinearLayoutManager(ViewBillDetails.this));
recyclerView.setAdapter(adapter);
}
}
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/AddOrEditBillActivity.java#L109
https://realm.io/docs/java/latest/#rxjava

14. REALM - A MOBILE DATABASE REPLACEMENT
OK, SO HOW DO I USE IT?
▸There is no schema set up
▸Simply have your model classes extend RealmObject
public class Bill extends RealmObject {
@PrimaryKey
public String uuid;
public String name;
public String description;
public int repeatingType = 0;
public Date dueDate;
public String payUrl;
public RealmList<BillNote> notes;
public RealmList<BillPaid> paidDates;
public boolean deleted = false;
public int amountDue = 0;
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/models/Bill.java

15. REALM - A MOBILE DATABASE REPLACEMENT
FIELD TYPES
▸Supports standard field types including Date
Realm supports the following field types: boolean, byte, short, int, long, float,
double, String, Date and byte[]. The integer types byte, short, int, and long are all
mapped to the same type (long actually) within Realm. Moreover, subclasses of
RealmObject and RealmList<? extends RealmObject> are supported to model
relationships.
The boxed types Boolean, Byte, Short, Integer, Long, Float and Double can also
be used in model classes. Using these types, it is possible to set the value of a
field to null.
https://realm.io/docs/java/latest/#field-types

16. REALM - A MOBILE DATABASE REPLACEMENT
QUERIES - CONDITIONS
‣ between(), greaterThan(), lessThan(),
greaterThanOrEqualTo() & lessThanOrEqualTo()
‣ equalTo() & notEqualTo()
‣ contains(), beginsWith() & endsWith()
‣ isNull() & isNotNull()
‣ isEmpty() & isNotEmpty()
https://realm.io/docs/java/latest/#conditions

17. REALM - A MOBILE DATABASE REPLACEMENT
QUERIES
▸You can group conditions for complex queries
RealmResults<User> r = realm.where(User.class)
.greaterThan("age", 10) //implicit AND
.beginGroup()
.equalTo("name", "Peter")
.or()
.contains("name", "Jo")
.endGroup()
.findAll();
https://realm.io/docs/java/latest/#logical-operators

18. REALM - A MOBILE DATABASE REPLACEMENT
CREATING MODEL
realm.beginTransaction();
User user = realm.createObject(User.class);
user.setName("John");
user.setEmail("john@corporation.com");
realm.commitTransaction();
https://realm.io/docs/java/latest/#creating-objects

19. REALM - A MOBILE DATABASE REPLACEMENT
CREATING MODEL
final Bill b = new Bill(name.getText().toString(), "", repeatingItem.code,
selectedDueDate.toDate(), payUrl.getText().toString(), (int) (amount.getValue() *
100));
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
realm.copyToRealm(b);
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/AddOrEditBillActivity.jav
a#L171

20. REALM - A MOBILE DATABASE REPLACEMENT
READING MODEL
BillTrackerApplication.getRealm().where(Bill.class).contains("
uuid", billUuid).findFirst()
‣ findFirst()
‣ findAll()
‣ findAllSorted()
‣ These all have an async version as well
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/AddOrEditBill
Activity.java#L109

21. REALM - A MOBILE DATABASE REPLACEMENT
UPDATING MODEL
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
editBill.setName(name.getText().toString());
editBill.setRepeatingType(repeatingItem.code);
editBill.setDueDate(selectedDueDate.toDate());
editBill.setPayUrl(payUrl.getText().toString());
editBill.setAmountDue((int) (amount.getValue() * 100));
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/AddOrEditBill
Activity.java#L155

22. REALM - A MOBILE DATABASE REPLACEMENT
DELETING MODEL
getRealm().executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
bill.deleteFromRealm();
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/AddOrEditBill
Activity.java#L218

23. REALM - A MOBILE DATABASE REPLACEMENT
RELATIONSHIPS
▸Many-to-One
▸Used for One-to-One
▸Many-to-Many
https://realm.io/docs/java/latest/#relationships

24. REALM - A MOBILE DATABASE REPLACEMENT
MANY-TO-ONE
public class Contact extends RealmObject {
private Email email;
// Other fields…
}
https://realm.io/docs/java/latest/#many-to-one

25. REALM - A MOBILE DATABASE REPLACEMENT
MANY-TO-MANY
public class Bill extends RealmObject {
…
public RealmList<BillPaid> paidDates;
…
}
final BillPaid billPaid = new BillPaid(new Date());
BillTrackerApplication.getRealm().executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
bill.setDueDate(DateUtil.createNextDueDate(bill));
bill.getPaidDates().add(billPaid);
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/models/Bill.java#L28
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/util/BillUtil.java#L20
https://realm.io/docs/java/latest/#many-to-many

26. REALM - A MOBILE DATABASE REPLACEMENT
THREADING
The only rule to using Realm across threads is to remember that
Realm, RealmObject or RealmResults instances cannot be passed
across threads.
Get Realm in any thread you need it.
getRealm().where(Bill.class).equalTo("deleted",
false).findAllSortedAsync("dueDate");
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/util/BillUtil.java#L43

27. REALM - A MOBILE DATABASE REPLACEMENT
USING WITH RETROFIT
It just works!
apiService.getUserBills(BillTrackerApplication.getUserToken()).enqueue(new Callback<List<Bill>>() {
@Override
public void onResponse(Call<List<Bill>> call, final Response<List<Bill>> response) {
for (Bill b : response.body()) {
Log.d("Bill", b.toString());
}
BillTrackerApplication.getRealm().executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
realm.copyToRealmOrUpdate(response.body());
}
});
}
});
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/network/controller
s/BillApi.java#L45

28. REALM - A MOBILE DATABASE REPLACEMENT
ADAPTERS
‣ RealmRecyclerViewAdapter
‣ Keeps the data updated from a RealmResult or RealmList
‣ No need to notifyDataSetChanged()
https://github.com/djrausch/BillTracker/blob/master/app/src/main/java/com/djrausch/billtracker/adapters/M
ainRecyclerViewAdapter.java
https://realm.io/docs/java/latest/#adapters

29. REALM - A MOBILE DATABASE REPLACEMENT
LIMITATIONS
▸The upper limit of class names is 57 characters. Realm for Android
prepend class_ to all names, and the browser will show it as part of
the name.
▸The length of field names has a upper limit of 63 character.
▸Nested transactions are not supported, and an exception is thrown if
they are detected.
▸Strings and byte arrays (byte[]) cannot be larger than 16 MB.
▸Does not support lists of primitive types (String, Ints, etc), yet.
https://realm.io/docs/java/latest/#current-limitations

30. REALM - A MOBILE DATABASE REPLACEMENT
QUESTIONS?
▸Use #phxmobi as the twitter hashtag and follow
@phxmobifestival for updates.
▸Download Phoenix Mobile Festival App (search for 'phxmobi')
from AppStore or Google Play. From the app you can create your
own agenda for the day and provide feedback on the sessions.
▸Slides will be on djraus.ch/realm soon!
▸Bill Tracker is open source -
https://github.com/djrausch/BillTracker