SquiDB: Android SQLite Management

DroidCon Tel Aviv 2015

What is SquiDB?

SQLite with Android string theory

SQLiteDatabase

public Cursor query(String table, String[] columns, ! String selection, String[] selectionArgs, ! String groupBy, String having, String orderBy, ! String limit) !public Cursor rawQuery(String sql, String[] sqlArgs) !!public long insert(String table, String ! nullColumnHack, ContentValues values) !public int update(String table, ContentValues values, ! String selection, String[] selectionArgs) !public int delete(String table, String selection, ! String[] selectionArgs) !!public void execSQL(String sql, String[] sqlArgs) !

SQLiteOpenHelper

SQLiteDatabase

SQLite with SquiDB bring back the fun

Models

§  Models generated at compile time ›  Define model using minimalist “spec” class ›  <type>Property for each member field (column) ›  Getters and setters for each property

§  Internally represented by ContentValues ›  Models are Parcelable!

§  Multiple sets of values ›  Tracks deltas; update only saves changed (written) values ›  Data source ordering

Model Specs

Sample Model

FilmDatabase

film_roles!!_id (PK) !film_id (FK) !actor_id (FK) !role !

actors !!_id (PK) !name !birthdate !gender!!

films !!_id (PK) !title !description !photo_url!year !rating !is_favorite!

index films.year!

index films.rating!

Sample Database

DatabaseDao

§  Controls access to database ›  CRUD operations ›  Transaction management

§  fetch(), persist(), and delete() single records §  update() and deleteWhere() for multiple records §  count() for number of matching rows §  query() for cursors

DatabaseDao

DatabaseDao

Queries

§  Object-oriented builder classes §  Supports almost the entire SELECT grammar

›  Joins, nested queries, compound operators ›  Functions and other complex expressions

§  Automatic placeholders and argument binding §  Reusable

›  Cached compilation ›  Use atomics to change arguments between executions

Queries

§  Select Fields, Properties, and Functions ›  Query.select(Film.PROPERTIES); // all Film properties !›  Query.select(Film.ID, Film.TITLE); // just these ones !›  Query.select(Function.max(Film.RATING)); // function !›  Query.select() // select * -- until you selectMore() !!

§  Predicates formed using Criterions ›  Film.IS_FAVORITE.isTrue() // from a Property !›  Film.YEAR.between(2010, 2015).and(Film.RATING.gte(4.0)) !›  Criterion.all, Criterion.none // pre-packaged !›  Criterion.not(Film.TITLE.like("L%")) !

Queries

Queries

Queries

SquidCursor

§  Parameterized CursorWrapper §  Read values using Property

›  String title = cursor.get(Film.TITLE); !§  Populate models easily

›  Film film = new Film(cursor); // must be at valid position !›  film.readPropertiesFromCursor(cursor); !

§  Model reusability ›  Film film = new Film(); !SquidCursor<Film> c = dao.query(Film.class, query); !for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) { ! film.readPropertiesFromCursor(c); ! doSomethingWithFilm(film); !} !

Other useful bits

§  SquidCursorAdapter ›  Base list adapter backed by a SquidCursor

§  SquidCursorLoader ›  Loader for querying DatabaseDao in the background

§  UriNotifier ›  Send URI notifications when write operations happen

Advanced features

§  Other SQLite statements ›  Inserts, updates, deletes, triggers

§  Models based on SQLite Views §  Utilities for building ContentProviders

›  Public contract vs. private schema ›  Protect against SQL injection

§  Code generator plugins ›  Use other Java types in your model specs

Questions? answers ?

Get started with SquiDB

Source: github.com/yahoo/squidb

Wiki:

github.com/yahoo/squidb/wiki