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

Build Status Download


Define entities from an abstract class:

abstract class AbstractPerson {

    @Key @Generated
    int id;

    @Index("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() {
    // getter, setters, equals & hashCode automatically generated into

or from an interface:

public interface Person {

    @Key @Generated
    int getId();

    String getName();

    Set<Phone> getPhoneNumbers();

    String getEmail();

or use immutable types such as those generated by @AutoValue:

abstract class Person {

    static abstract class Builder {
        abstract Builder setId(int id);
        abstract Builder setName(String name);
        abstract Builder setEmail(String email);
        abstract Person build();

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

    abstract int getId();

    abstract String getName();
    abstract String getEmail();

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

Queries: dsl based query that maps to SQL

Result<Person> query = data

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

abstract class AbstractPerson {

    @Key @Generated
    int id;

    Result<Group> groups;
    // equivalent to:
    // .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))

Kotlin specific support using property references and infix functions:

data {
    val result = select(Person::class) where (Person::age gt 21) and (Person::name eq "Bob") limit 10

Java 8 streams:

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

RxJava observe query on table changes:

Observable<Person> observable = data

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

int rows = data.update(Person.class)
    .set(Person.ABOUT, "student")


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.

Query with Java

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.


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.

vs JPA

requery provides a modern set of interfaces for persisting and performing queries. Some key differences between requery and JPA providers like Hibernate or EclipseLink:


Designed specifically with Android support in mind. See requery-android/example for an example Android project using databinding and interface based entities. For more information see the Android page.

Supported Databases

Tested on some of the most popular databases:

JPA Annotations

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


Upserts are generated with the appropriate database specific query statements:

Using it

Versions are available on bintray jcenter / maven central.

repositories {

dependencies {
    compile 'io.requery:requery:1.6.1'
    compile 'io.requery:requery-android:1.6.1' // for android
    annotationProcessor 'io.requery:requery-processor:1.6.1'

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


Copyright (C) 2019

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

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.