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requery

A light but powerful ORM and SQL query generator for Java/Android with RxJava and Java 8 support. Easily map to or create databases, perform queries and updates from any platform that uses Java.

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Examples

Define entities from an abstract class:

@Entity
abstract class AbstractPerson {

    @Key @Generated
    int id;

    @Index(name = "name_index")              // table specification
    String name;

    @OneToMany                               // relationships 1:1, 1:many, many to many
    Set<Phone> phoneNumbers;

    @Converter(EmailToStringConverter.class) // custom type conversion
    Email email;

    @PostLoad                                // lifecycle callbacks
    void afterLoad() {
        updatePeopleList();
    }

    // getter, setters, equals & hashCode automatically generated into Person.java
}

or from an interface:

@Entity
public interface Person {

    @Key @Generated
    int getId();

    String getName();

    @OneToMany
    Set<Phone> getPhoneNumbers();

    String getEmail();
}

Queries: dsl based query that maps to SQL

Result<Person> query = data
    .select(Person.class)
    .where(Person.NAME.lower().like("b%")).and(Person.AGE.gt(20))
    .orderBy(Person.AGE.desc())
    .limit(5)
    .get();

Relationships: represent relations more efficiently with Java 8 Streams, RxJava Observables or plain iterables. (sets and lists are supported to)

@Entity
abstract class AbstractPerson {

    @Key @Generated
    int id;

    @ManyToMany
    Result<Group> groups;
    // equivalent to:
    // data.select(Group.class)
    // .join(Group_Person.class).on(Group_ID.equal(Group_Person.GROUP_ID))
    // .join(Person.class).on(Group_Person.PERSON_ID.equal(Person.ID))
    // .where(Person.ID.equal(id))
}

Java 8 streams:

data.select(Person.class)
    .orderBy(Person.AGE.desc())
    .get()
    .stream().forEach(System.out::println);

Java 8 optional and time support:

public interface Person {

    @Key @Generated
    int getId();

    String getName();
    Optional<String> getEmail();
    ZonedDateTime getBirthday();
}

RxJava Observables:

Observable<Person> observable = data
    .select(Person.class)
    .orderBy(Person.AGE.desc())
    .get()
    .toObservable();

RxJava observe query on table changes:

Observable<Person> observable = data
    .select(Person.class)
    .orderBy(Person.AGE.desc())
    .get()
    .toSelfObservable().subscribe(::updateFromResult);

Immutable types Combine requery/JPA attributes on @AutoValue and other generated immutable types.

@AutoValue
@Entity
abstract class Person {

    @AutoValue.Builder
    static abstract class Builder {
        abstract Builder setId(int id);
        abstract Builder setName(String name);
        abstract Builder setBirthday(Date date);
        abstract Builder setAge(int age);
        abstract Person build();
    }

    static Builder builder() {
        return new AutoValue_Person.Builder();
    }

    @Id @GeneratedValue
    abstract int getId();

    abstract String getName();
    abstract Date getBirthday();
    abstract int getAge();
}

(Note some features will not be available when using immutable types, see the wiki)

Read/write separation Along with immutable types optionally separate queries (reading) and updates (writing):

int rows = data.update(Person.class)
    .set(Person.ABOUT, "nothing")
    .set(Person.AGE, 50)
    .where(Person.AGE.equal(100)).get();

Features

  • No Reflection
  • Fast startup & performance
  • No dependencies (RxJava is optional)
  • Typed query language
  • Table generation
  • Supports JDBC and many popular databases
  • Supports Android (SQLite, RecyclerView, Databinding, SQLCipher)
  • RxJava support
  • Blocking and non-blocking API
  • Partial objects/refresh
  • Caching
  • Lifecycle callbacks
  • Custom type converters
  • Compile time entity validation
  • JPA annotations (however requery is not a JPA provider)

Reflection free

requery uses compile time annotation processing to generate entity model classes and mapping attributes. On Android this means you get about the same performance reading objects from a query as if it was populated using the standard Cursor and ContentValues API.

Type safe query

The compiled classes work with the query API to take advantage of compile time generated attributes. Create type safe queries and avoid hard to maintain, error prone string concatenated queries.

Relationships

You can define One-to-One, One-to-Many, Many-to-One, and Many-to-Many relations in your models using annotations. Relationships can be navigated in both directions. Of many type relations can be loaded into standard java collection objects or into a more efficient Result type. From a Result easily create a Stream, RxJava Observable, Iterator, List or Map.

Many-to-Many junction tables can be generated automatically. Additionally the relation model is validated at compile time eliminating runtime errors.

Android

Designed specifically with Android support in mind.

Comparison to similar Android libraries:

Feature requery ORMLite Squidb DBFlow GreenDao
Relational mapping Y Y(1) N Y Y(1)
Inverse relationships Y N N N N
Compile time Y N Y Y Y(2)
Query DSL Y N N(3) N(3) N(3)
JDBC Support Y Y N N N
Table Generation Y Y Y Y Y
JPA annotations Y Y N N N
RxJava support Y N Y(4) N N
  1. Excludes Many-to-Many
  2. Not annotation based
  3. Builder only not DSL
  4. Table changes only

See requery-android/example for an example Android project using databinding and interface based entities. For more information see the Android page.

Code generation

Generate entities from Abstract or Interface classes. Use JPA annotations or requery annotations. requery will generate getter/setters, equals() and hashcode() when needed.

Supported Databases

Tested on some of the most popular databases:

  • PostgresSQL (9.1+)
  • MySQL 5.x
  • Oracle 12c+
  • Microsoft SQL Server 2012 or later
  • SQLite (Android or with the xerial JDBC driver)
  • Apache Derby 10.11+
  • H2 1.4+
  • HSQLDB 2.3+

JPA Annotations

A subset of the JPA annotations that map onto the requery annotations are supported. See here for more information.

Using it

Currently beta versions are available on bintray.

repositories {
    jcenter()
}

dependencies {
    compile 'io.requery:requery:1.0.0-beta2'
    compile 'io.requery:requery-android:1.0.0-beta2' // for android
    apt 'io.requery:requery-processor:1.0.0-beta2'   // use an APT plugin
}

For more information on gradle and annotation processing & gradle see the wiki.

License

Copyright (C) 2016 requery.io

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.