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Speeding up development with AutoValue and
SQLDelight
Andrii Rakhimov
Mkhytar Mkhoian
Lalafo
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"The best code is code not written"
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Problems
public class User implements Parcelable {
public static final Creator CREATOR = new Creator() {
@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;
}
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Problems
● DRY
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Problems
● DRY
● Mutable
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Problems
● DRY
● Mutable
● Maintainability
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No content
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AutoValue to the rescue
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Value classes
public class Money {
public Currency currency;
public long amount;
}
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How does it works?
@AutoValue public abstract class User {
@Nullable public abstract String username();
public abstract String email();
}
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How does it works?
@Retention(RetentionPolicy.SOURCE)
@Target({ ElementType.TYPE})
public @interface AutoValue {
@Retention(RetentionPolicy.SOURCE)
@Target({ElementType.TYPE})
public @interface Builder {
}
}
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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.
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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
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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; do not mutate the
* returned object.
*/
public abstract MutablePropertyType ouch();
}
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AutoValue Extensions, API-invisible
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Parcelable
final class AutoValue_User extends $AutoValue_User {
public static final Parcelable.Creator CREATOR = new
Parcelable.Creator() {
@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];
}
...
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Gson
@AutoValue public abstract class User implements Parcelable {
@Nullable public abstract String username();
public abstract String email();
public static TypeAdapter typeAdapter(Gson gson) {
return new AutoValue_User.GsonTypeAdapter(gson);
}
}
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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();
}
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Gson
abstract class $AutoValue_User extends $$AutoValue_User {
...
public static final class GsonTypeAdapter extends TypeAdapter {
...
@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;
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TypeAdapters for free
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No content
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All Extensions
● JSON(Gson/Jackson)
● Parcelable
● Cursor
● Firebase
● Redact(Omitting selected fields from toString())
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Pros/Cons
● DRY
● Immutable(Type-safe, null-safe and thread-safe)
● Maintainable(180->20, no need for tests(builder), faster PRs)
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Pros/Cons
● DRY
● Immutable(Type-safe, null-safe and thread-safe)
● Maintainable(180->20, no need for tests(builder), faster PRs)
● API-invisible
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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
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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
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Cons
● Require to compile
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Cons
● Require to compile
● Fabrics for class instantiation may break
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Cons
● Require to compile
● Fabrics for class instantiation may break
● Mutable fields, arrays, lists
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SQLDelight
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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);
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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;
}
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Features that we want:
● RxJava
● Immutability
● Type Safety
● Compiler Errors
● SQLite features
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Features that we want:
● RxJava - SQLBrite
● Immutability
● Type Safety
● Compiler Errors
● SQLite features
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Features that we want:
● RxJava - SQLBrite
● Immutability - AutoValue
● Type Safety
● Compiler Errors
● SQLite features
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Features that we want:
● RxJava - SQLBrite
● Immutability - AutoValue
● Type Safety - SQLDelight
● Compiler Errors - SQLDelight
● SQLite features - SQLDelight
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Package structure
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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
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Java model
@AutoValue public abstract class Image implements ImagesModel {
public static final Factory![]()
FACTORY = new Factory<>(new Creator![]()
() {
@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![]()
GET_ALL_IMAGES_MAPPER = FACTORY.getAllImagesMapper();
public static final RowMapper![]()
GET_IMAGES_BY_ID_MAPPER = FACTORY.getImagesByIdMapper();
}
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Cursor mapper
final class Mapper implements RowMapper {
private final Factory imagesModelFactory;
public Mapper(Factory 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));
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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 (?, ?);
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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();
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Example of query
getImagesById:
SELECT *
FROM images
WHERE ad_id = ?
ORDER BY _id ASC;
public SqlDelightStatement getAdsByStatus(@NonNull Ad.Status status) {
List args = new ArrayList();
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.singleton("ads"));
}
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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);
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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);
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Query with join
selectAll:
SELECT *
FROM ads
JOIN images ON ads.ad_id = images.ad_id;
interface SelectAllModel {
@NonNull
T1 ads();
@NonNull
T2 images();
}
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Query with join
public static final RowMapper SELECT_ALL_MAPPER = FACTORY.selectAllMapper(
new SelectAllCreator() {
@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 { }
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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
);
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Support imports like Java in .sq files
public final class DateAdapter implements ColumnAdapter {
@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;
}
}
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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_ADAPTER = EnumColumnAdapter.create(Status.class);
public static final Factory FACTORY = new Factory<>(new Creator() {
@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);
}
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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);
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SQLDelight with SQLBrite
private BriteDatabase db;
private Observable 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);
}
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● 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
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Conclusion
● RxJava, Immutability, Type Safety, Compiler Errors, SQLite features
● Shared language
● Tight coupling with views (MVVM)
● Easier code review
● Confidence writing SQL
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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 | [email protected]
Mkhytar Mkhoian - https://www.facebook.com/mkhytar.mkhoian | [email protected]