Copyright © 2016-2018

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1. Introduction

This module provides a set of QueryDSL integration features for the JPA Datastore module.

The required QueryDSL version is 4.x or higher.
You must provide the QueryDSL artifacts dependencies in classpath, since they are not provided by this module.

Maven coordinates:

<groupId>com.holon-platform.jpa</groupId>
<artifactId>holon-datastore-jpa-querydsl</artifactId>
<version>5.2.0</version>

1.1. Sources and contributions

The Holon Platform JPA QueryDSL integration module source code is available from the GitHub repository https://github.com/holon-platform/holon-datastore-jpa-querydsl.

See the repository README file for information about:

  • The source code structure.

  • How to build the module artifacts from sources.

  • Where to find the code examples.

  • How to contribute to the module development.

2. Obtaining the artifacts

The Holon Platform uses Maven for projects build and configuration. All the platform artifacts are published in the Maven Central Repository, so there is no need to explicitly declare additional repositories in your project pom file.

A BOM (Bill Of Materials) pom is provided to import the available dependencies for a specific version in your projects.

The BOM can be imported in a Maven project in the following way:

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.holon-platform.jpa</groupId>
      <artifactId>holon-datastore-jpa-querydsl-bom</artifactId>
      <version>5.2.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

2.1. Using the Platform BOM

The Holon Platform provides an overall Maven BOM (Bill of Materials) to easily obtain all the available platform artifacts.

3. Data targets

The QueryDslTarget interface can be used to create a DataTarget using a QueryDSL EntityPath, which represents a JPA entity root path.

final QueryDslTarget<Test> TARGET = QueryDslTarget.of(QTest.test); (1)

Datastore datastore = getDatastore(); // build or obtain a JPA Datastore

datastore.refresh(TARGET, value); (2)
1 Create a DataTarget using the QueryDSL EntityPath for the JPA Test entity class
2 Use the target with a Datastore

4. Properties

The QueryDslProperty interface can be used to create a PathProperty from a QueryDSL Path. The of(Path<T> path) method returns a builder which can be used to setup property configuration and attributes and automatically set the root EntityPath as parent property path.

final QueryDslProperty<Long> ID = QueryDslProperty.of(QTest.test.id); (1)
final QueryDslProperty<String> NAME = QueryDslProperty.of(QTest.test.name); (2)

Datastore datastore = getDatastore(); // build or obtain a JPA Datastore

datastore.save(QueryDslTarget.of(QTest.test),
    PropertyBox.builder(ID, NAME).set(ID, 1L).set(NAME, "TestName").build()); (3)
1 Create a PathProperty using the QueryDSL Path of the JPA Test entity class id attribute of type Long
2 Create a PathProperty using the QueryDSL Path of the JPA Test entity class name attribute of type String
3 Use the created properties within a PropertyBox in a Datastore operation

5. QueryDSL JPA Datastore Commodity

The QueryDSL JPA integration module automatically registers the QueryDsl JPA Datastore commodity, which provides a set of methods to build QueryDSL queries and bulk operation executors.

To obtain the commodity the standard Datastore create(…​) method can be used:

Datastore datastore = getDatastore(); // build or obtain a JPA Datastore

QueryDsl queryDslCommodity = datastore.create(QueryDsl.class); (1)

JpaQuery<?> query = queryDslCommodity.query(); (2)
query = queryDslCommodity.selectFrom(QTest.test); (3)

queryDslCommodity.update(QTest.test).set(QTest.test.name, "UpdatedName").where(QTest.test.id.eq(1L)).execute(); (4)
queryDslCommodity.delete(QTest.test).where(QTest.test.id.loe(1L)).execute(); (5)
1 Create a QueryDsl commodity
2 Obtain a query
3 Obtain a query setting the from clause
4 Configure and execute a bulk update
5 Configure and execute a bulk delete

The JpaQuery class is an extension of the default QueryDSL JPA query and allows to mix QueryDSL expressions and predicates with standard platform query expressions, such as QueryFilter, QuerySort and QueryAggregation.

Datastore datastore = getDatastore(); // build or obtain a JPA Datastore

final PathProperty<Long> ID = QueryDslProperty.of(QTest.test.id); (1)
final StringProperty NAME = StringProperty.create("name"); (2)

long count = getDatastore().create(QueryDsl.class).query().from(QTest.test)
    .filter(ID.gt(2L).and(NAME.startsWith("n"))).count(); (3)
1 Create a PathProperty using a QueryDSL Path
2 Create a PathProperty using standard create method, providing property name and type
3 Create and execute a QueryDSL JpaQuery, mixing QueryDSL expressions and standard `PathProperty`s

6. Spring Boot starters

The following starter artifacts are available to provide a quick project configuration setup using Maven dependency system:

1. The QueryDSL JPA starter using Hibernate provides dependencies to the default Holon JPA Datastore Spring Boot starter using the Hibernate ORM as persistence provider, in addition to the Holon Platform QueryDSL integration dependencies.

Maven coordinates:

<groupId>com.holon-platform.jpa</groupId>
<artifactId>holon-starter-jpa-querydsl-hibernate</artifactId>
<version>5.2.0</version>

2. The QueryDSL JPA starter using Eclipselink provides dependencies to the default Holon JPA Datastore Spring Boot starter using the Eclipselink as persistence provider, in addition to the Holon Platform QueryDSL integration dependencies.

Maven coordinates:

<groupId>com.holon-platform.jpa</groupId>
<artifactId>holon-starter-jpa-querydsl-eclipselink</artifactId>
<version>5.2.0</version>

7. Loggers

By default, the Holon platform uses the SLF4J API for logging. The use of SLF4J is optional: it is enabled when the presence of SLF4J is detected in the classpath. Otherwise, logging will fall back to JUL (java.util.logging).

The logger name for the JPA Datastore QueryDSL integration module is com.holonplatform.datastore.jpa.

8. System requirements

8.1. Java

The Holon Platform JPA Datastore QueryDSL module requires Java 8 or higher.

8.2. QueryDSL

QueryDSL JPA version 4.x is required and must be available in classpath to use the JPA Datastore QueryDSL module.