Querydsl

Description

Querydsl is a framework which enables the construction of type-safe SQL-like queries for multiple backends including JPA, JDO and SQL.

Instead of writing queries as inline strings or externalizing them into XML files they are constructed via a fluent API.

The benefits of using a fluent API in comparison to simple strings are

code completion in IDE (all properties, methods and operations can be expanded in your favorite Java IDE)
almost no syntactically invalid queries allowed (type-safe on all levels)
domain types and properties can be referenced safely (no Strings involved!)
adopts better to refactoring changes in domain types
incremental Query definition is easier

Modules

Module	description	artifactId	depends on
Core	core API of Querydsl	querydsl-core
APT	APT based code generation	querydsl-apt	Core
SQL	JDBC/SQL support	querydsl-sql	Core, APT
Lucene	Lucene support	querydsl-lucene	Core
Collections	Java collections support	querydsl-collections	Core
HQL	HQL/JPQL support	querydsl-hql	Core, APT, SQL
JDOQL	JDOQL support	querydsl-jdoql	Core, APT
Hibernate Search	Hibernate Search support	querydsl-hibernate-search	Core, Lucene

Supported backends

JPA / Hibernate

Getting started with Querydsl using Hibernate
via the querydsl-hql module
tested with Hibernate using Derby, HSQLDB and MySQL

JDO

Getting started with Querydsl using JDO
via the querydsl-jdoql module
tested with DataNucleus Access Platform

Java Collections

Getting started using Querydsl for Collections
via the querydsl-collections module

SQL

Getting started using Querydsl for SQL
via the querydsl-sql module
supports Derby, HSQLDB, MySQL (5.1), Postgres (8.4), Oracle (10/11) and MS SQL Server (2008)

RDF

via RDFBean, our Object/RDF persistence framework
tested with RDFBean using Sesame

Lucene

Getting started using Querydsl for Lucene
via the querydsl-lucene module

Hibernate Search

Getting started using Querydsl for Hibernate Search
via the querydsl-hibernate-search module

Go to Documentation for Javadocs and the Reference Documentation and go to Examples to see examples.

In a nutshell

Name	Querydsl
Most Recent Version	1.8.0
Javadocs	v 1.8.0
Documentation	Documentation
Downloads	Downloads
State	Stable
License	LGPL v2.1
Version Control	on Mysema Source
Maven repo	on Mysema Source
Issue Management	on Launchpad
Commercial Support	contact us

Querydsl users talking

"If you are using JPA and want to write typesafe queries in an IDE, then stop using the JPA 2.0 Criteria API and start using Querydsl. Today."

Bob Walker

"So, here is my tip to anyone thinking about using a Criteria API: Give Querydsl a try! By the way, did I mention that it can also be used with JDO, Lucene, JDBC and even plain collections? "

Luis Fernando Planella Gonzalez

"Querydsl rocks! It's the best thing since sliced bread for data access in Java."

Alex Besogonov

"Using querydsl you keep the reference to your HibernateQuery object and you can apply as many joins, wheres etc as you can, in any order, so that you can get a totally mutable hql query without ugly string concatenation. "

Lukasz Wisniewski

"Querydsl has been easy to get running, and easy to write compact and readable queries in. Integration in an existing project has been as painless as it could be, and we have had almost no problems."

Stein Magnus Jodal