Speeding up development with AutoValue and SQLDelight

1. Speeding up development with AutoValue and SQLDelight Andrii Rakhimov Mkhytar Mkhoian Lalafo
2. "The best code is code not written"
3. Problems public class User implements Parcelable { public static final Creator<User> CREATOR = new Creator<User>() { @Override public User createFromParcel(Parcel in) { return new User(in); } @Override public User[] newArray(int size) { return new User[size]; } }; @SerializedName("username") private String userName; @SerializedName("email") private String email; public User(String userName) { this.userName = userName; } protected User(Parcel in) { userName = in.readString(); email = in.readString(); } @Override public void writeToParcel(Parcel dest, int flags) { dest.writeString(userName); dest.writeString(email); } @Override public int describeContents() { return 0; } public String getUserName() { return userName; } public String setUserName(String userName) { this.userName = userName; } public String getEmail() { return email; } public String setEmail(String email) { this.email = email; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; User user = (User) o; if (userName != null ? !userName.equals(user.userName) : user.userName != null) return false; return email != null ? !email.equals(user.email) : user.email != null; } @Override public int hashCode() { int result = 31; result = 31 * result + (userName != null ? userName.hashCode() : 0); result = 31 * result + (email != null ? email.hashCode() : 0); return result; } @Override public String toString() { return "User{userName='" + userName + ", email='" + email; }
4. Problems • DRY
5. Problems • DRY • Mutable
6. Problems • DRY • Mutable • Maintainability
8. AutoValue to the rescue
9. Value classes public class Money { public Currency currency; public long amount; }
10. How does it works? @AutoValue public abstract class User { @Nullable public abstract String username(); public abstract String email(); }
11. How does it works? @Retention(RetentionPolicy.SOURCE) @Target({ ElementType.TYPE}) public @interface AutoValue { @Retention(RetentionPolicy.SOURCE) @Target({ElementType.TYPE}) public @interface Builder { } }
12. Generated implementation abstract class AutoValue_User extends User { private final String email; private final String username; AutoValue_User(String email, @Nullable String username) { if (email == null) { throw new NullPointerException("Null email"); } this.username = username; } ...getters, equals, hashcode, toString, etc.
13. Instantiation @AutoValue public abstract class User { public static Builder builder() { return new AutoValue_User.Builder(); } @AutoValue.Builder public abstract static class Builder { public abstract Builder email(String email); public abstract Builder username(String username); public abstract User build(); } } AS plugin to generate builders https://github.com/afcastano/AutoValuePlugin
14. Mutable types @AutoValue public abstract class MutableExample { public static MutableExample create(MutablePropertyType ouch) { // Replace `.clone` below with the right copying code for this type return new AutoValue_MutableExample(ouch.clone()); } /** * Returns the ouch associated with this object; <b>do not mutate</b> the * returned object. */ public abstract MutablePropertyType ouch(); }
15. AutoValue Extensions, API-invisible
16. Parcelable final class AutoValue_User extends $AutoValue_User { public static final Parcelable.Creator<AutoValue_User> CREATOR = new Parcelable.Creator<AutoValue_User>() { @Override public AutoValue_User createFromParcel(Parcel in) { return new AutoValue_User( in.readString(), in.readInt() == 0 ? in.readString() : null ); } @Override public AutoValue_User[] newArray(int size) { return new AutoValue_User[size]; } ...
17. Gson @AutoValue public abstract class User implements Parcelable { @Nullable public abstract String username(); public abstract String email(); public static TypeAdapter<User> typeAdapter(Gson gson) { return new AutoValue_User.GsonTypeAdapter(gson); } }
18. Gson @GsonTypeAdapterFactory public abstract class AdapterFactory implements TypeAdapterFactory { public static AdapterFactory create() { return new AutoValueGson_AdapterFactory(); } } @Provides @Singleton Gson provideGson() { return new GsonBuilder() .registerTypeAdapterFactory(AdapterFactory.create()) .create(); }
19. Gson abstract class $AutoValue_User extends $$AutoValue_User { ... public static final class GsonTypeAdapter extends TypeAdapter<User> { ... @Override public void write(JsonWriter jsonWriter, User object) throws IOException { if (object == null) { jsonWriter.nullValue(); return; } jsonWriter.beginObject(); jsonWriter.name("username"); usernameAdapter.write(jsonWriter, object.username()); jsonWriter.name("email"); emailAdapter.write(jsonWriter, object.email()); jsonWriter.endObject(); } } @Override public User read(JsonReader jsonReader) throws IOException { if (jsonReader.peek() == JsonToken.NULL) { jsonReader.nextNull(); return null; } jsonReader.beginObject(); String email = this.defaultEmail; String username = this.defaultUsername; while (jsonReader.hasNext()) { String _name = jsonReader.nextName(); if (jsonReader.peek() == JsonToken.NULL) { jsonReader.nextNull(); continue; } switch (_name) { case "username": { username = usernameAdapter.read(jsonReader); break; } case "email": { email = emailAdapter.read(jsonReader); break;
20. TypeAdapters for free
22. All Extensions • JSON(Gson/Jackson) • Parcelable • Cursor • Firebase • Redact(Omitting selected fields from toString())
23. Pros/Cons • DRY • Immutable(Type-safe, null-safe and thread-safe) • Maintainable(180->20, no need for tests(builder), faster PRs)
24. Pros/Cons • DRY • Immutable(Type-safe, null-safe and thread-safe) • Maintainable(180->20, no need for tests(builder), faster PRs) • API-invisible
25. Pros/Cons • DRY • Immutable(Type-safe, null-safe and thread-safe) • Maintainable(180->20, no need for tests(builder), faster PRs) • API-invisible • No runtime dependencies
26. Pros/Cons • DRY • Immutable(Type-safe, null-safe and thread-safe) • Maintainable(No need for tests(builder), faster PRs) • API-invisible • No runtime dependencies • Docs
27. Cons • Require to compile
28. Cons • Require to compile • Fabrics for class instantiation may break
29. Cons • Require to compile • Fabrics for class instantiation may break • Mutable fields, arrays, lists
30. SQLDelight
31. The problem static final String CREATE_CATEGORIES_TABLE = "create table " + Category.TABLE + "(" + COLUMN_ID + " integer primary key autoincrement, " + Category.COL_NAME + " text, " + Category.COL_COLOR + " integer, " + Category.COL_CREATE_BY_USER + " integer DEFAULT 0 " + ");"; cursor.getString(cursor.getColumnIndexOrThrow(columnName)); ContentValues values = new ContentValues(); values.put(COL_NAME, name);
32. The problem private static String LIST_QUERY(String selection) { String query = "SELECT *, COUNT(i." + ListItem.COL_STATUS + ") " + List.COL_SIZE + ", SUM(i." + ListItem.COL_STATUS + ") " + List.COL_BOUGHT_COUNT + " FROM " + List.TABLE + " s" + " LEFT OUTER JOIN " + ListItem.TABLE + " i" + " ON s." + List.COL_ID + " = i." + ListItem.COL_PARENT_LIST_ID; if (selection == null) { return query + " GROUP BY s." + List.COL_ID; } return query + " WHERE " + selection + " GROUP BY s." + List.COL_ID; }
33. Features that we want: • RxJava • Immutability • Type Safety • Compiler Errors • SQLite features
34. Features that we want: • RxJava - SQLBrite • Immutability • Type Safety • Compiler Errors • SQLite features
35. Features that we want: • RxJava - SQLBrite • Immutability - AutoValue • Type Safety • Compiler Errors • SQLite features
36. Features that we want: • RxJava - SQLBrite • Immutability - AutoValue • Type Safety - SQLDelight • Compiler Errors - SQLDelight • SQLite features - SQLDelight
37. Package structure
38. CREATE TABLE images ( _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, ad_id INTEGER NOT NULL, url TEXT, size TEXT, image_id TEXT ); saveImage: INSERT INTO images(ad_id, url, size, image_id) VALUES (?, ?, ?, ?); getAllImages: SELECT * FROM images; SQL statements
39. Java model @AutoValue public abstract class Image implements ImagesModel { public static final Factory<Image> FACTORY = new Factory<>(new Creator<Image>() { @Override public Image create(long _id, long ad_id, @Nullable String url, @Nullable String size, @Nullable String image_id) { return new AutoValue_Image(_id, ad_id, url, size, image_id); } }); public static final RowMapper<Image> GET_ALL_IMAGES_MAPPER = FACTORY.getAllImagesMapper(); public static final RowMapper<Image> GET_IMAGES_BY_ID_MAPPER = FACTORY.getImagesByIdMapper(); }
40. Cursor mapper final class Mapper<T extends ImagesModel> implements RowMapper<T> { private final Factory<T> imagesModelFactory; public Mapper(Factory<T> imagesModelFactory) { this.imagesModelFactory = imagesModelFactory; } @Override public T map(@NonNull Cursor cursor) { return imagesModelFactory.creator.create( cursor.getLong(0), cursor.getLong(1), cursor.isNull(2) ? null : cursor.getString(2), cursor.isNull(3) ? null : cursor.getString(3), cursor.isNull(4) ? null : cursor.getString(4) ); } } cursor.getString(cursor.getColumnIndexOrThrow(columnName));
41. Example of insertion final class SaveImage extends SqlDelightCompiledStatement.Insert { public SaveImage(SQLiteDatabase database) { super("images", database.compileStatement("" + "INSERT INTO images(ad_id, url)\n" + "VALUES (?, ?)")); } public void bind(long ad_id, @Nullable String url) { program.bindLong(1, ad_id); if (url == null) { program.bindNull(2); } else { program.bindString(2, url); } } } saveImage: INSERT INTO images(ad_id, url) VALUES (?, ?);
42. Example of insertion saveImage: INSERT INTO images(ad_id, url) VALUES (?, ?); Image.SaveImage saveImage = new ImagesModel.SaveImage(db); saveImage.bind(10, "url"); saveImage.program.executeInsert();
43. Example of query getImagesById: SELECT * FROM images WHERE ad_id = ? ORDER BY _id ASC; public SqlDelightStatement getAdsByStatus(@NonNull Ad.Status status) { List<String> args = new ArrayList<String>(); int currentIndex = 1; StringBuilder query = new StringBuilder(); query.append("SELECT *\n" + "FROM ads\n" + "WHERE status = "); query.append('?').append(currentIndex++); args.add((String) statusAdapter.encode(status)); return new SqlDelightStatement(query.toString(), args.toArray(new String[args.size()]), Collections.<String>singleton("ads")); }
44. Example of query getImagesById: SELECT * FROM images WHERE ad_id = ? ORDER BY _id ASC; SqlDelightStatement query = Image.FACTORY.getImagesById(10); Cursor cursor = db.rawQuery(query.statement, query.args); Ad.FACTORY.getAdsByStatusMapper().map(cursor);
45. Sets of values also can be passed as an argument getImagesById: SELECT * FROM images WHERE ad_id IN ? or WHERE ad_id IN :param_name ORDER BY _id ASC; SqlDelightStatement query = Image.FACTORY.getImagesById(new long[]{10, 20}); Cursor cursor = db.rawQuery(query.statement, query.args);
46. Query with join selectAll: SELECT * FROM ads JOIN images ON ads.ad_id = images.ad_id; interface SelectAllModel<T1 extends AdModel, T2 extends ImagesModel> { @NonNull T1 ads(); @NonNull T2 images(); }
47. Query with join public static final RowMapper<AdWithImages> SELECT_ALL_MAPPER = FACTORY.selectAllMapper( new SelectAllCreator<Ad, Image, AdWithImages>() { @Override public AdWithImages create(@NonNull Ad ads, @NonNull Image images) { return new AutoValue_Ad_AdWithImages(ads, images); } }, Image.FACTORY); @AutoValue public static abstract class AdWithImages implements SelectAllModel<Ad, Image> { }
48. Support imports like Java in .sq files import com.justplay1.sqldelight.models.Ad.Status; import java.util.Calendar; CREATE TABLE ads ( _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, ad_id INTEGER NOT NULL UNIQUE ON CONFLICT IGNORE, title TEXT, description TEXT, price TEXT, status TEXT AS Status NOT NULL, create_time INTEGER AS Calendar NOT NULL, is_favorite INTEGER AS Boolean NOT NULL DEFAULT 0 );
49. Support imports like Java in .sq files public final class DateAdapter implements ColumnAdapter<Calendar, Long> { @Override public Long encode(@NonNull Calendar date) { return date.getTimeInMillis(); } @Override @NonNull public Calendar decode(Long data) { Calendar calendar = Calendar.getInstance(); calendar.setTimeInMillis(data); return calendar; } }
50. Support imports like Java in .sq files @AutoValue public abstract class Ad implements AdModel { public enum Status { ACTIVE, DEACTIVATED } private static final DateAdapter DATE_ADAPTER = new DateAdapter(); private static final EnumColumnAdapter<Status> STATUS_ADAPTER = EnumColumnAdapter.create(Status.class); public static final Factory<Ad> FACTORY = new Factory<>(new Creator<Ad>() { @Override public Ad create(long _id, long ad_id, @Nullable String title, @NonNull Status status, @NonNull Calendar create_time, boolean is_favorite) { return new AutoValue_Ad(_id, ad_id, title, status, create_time, is_favorite); } }, STATUS_ADAPTER, DATE_ADAPTER); }
51. Support to pass any type into query from java CREATE TABLE ads ( status TEXT AS Status NOT NULL ); getAdsByStatus: SELECT * FROM ads WHERE status = ?; SqlDelightStatement query = Ad.FACTORY.getAdsByStatus(Ad.Status.ACTIVE); Cursor cursor = db.rawQuery(query.statement, query.args);
52. SQLDelight with SQLBrite private BriteDatabase db; private Observable<Ad> getAd() { SqlDelightStatement statement = Ad.FACTORY.getAdsByStatus(Ad.Status.ACTIVE); return db.createQuery(statement.tables, statement.statement, statement.args) .mapToOne(Ad.ADS_BY_STATUS_MAPPER::map); }
53. • Syntax highlighting • Refactoring/Find usages • Code autocompletion • Generate Model files after edits • Right click to copy as valid SQLite • Compiler errors in IDE click through to file Intellij IDEA plugin
54. Conclusion • RxJava, Immutability, Type Safety, Compiler Errors, SQLite features • Shared language • Tight coupling with views (MVVM) • Easier code review • Confidence writing SQL
55. Links and contacts AutoValue - https://github.com/google/auto/blob/master/value/userguide/index.md AutoValue plugins for AS - https://github.com/afcastano/AutoValuePlugin https://github.com/robohorse/RoboPOJOGenerator AutoValue Extensions - https://github.com/blipinsk/awesome-auto-value-extensions SQLDelight - https://github.com/square/sqldelight SQLBrite - https://github.com/square/sqlbrite Rakhimov Andrii - https://www.facebook.com/profile.php?id=100000447429343 | ar090g@gmail.com Mkhytar Mkhoian - https://www.facebook.com/mkhytar.mkhoian | mkhytar.mkhoian@gmail.com