Mapping Extension API

Table of Contents

• JNoSQL Lite
  • Extension Steps
  • Usage and Limitations
• JNoSQL Static Metamodel
  • Installing the Metamodel Processor
  • Example Usage
• Bean Validation
• CriteriaQuery API
  • Set dependency
• Driver for Jakarta Persistence entities
• TCK Runners
  • Jakarta Data TCK Runner
• Getting Help
• Contributing

The Eclipse JNoSQL Mapping Extension API is a collection of implementations/specializations from the Jakarta NoSQL specification that defines specific behavior in various NoSQL databases.

JNoSQL Lite

This documentation guides extending the usage of Eclipse JNoSQL to avoid using Reflection with Java Annotation Processor while still utilizing the same APIs and achieving compatibility with CDI Lite.

The extension approach aims to achieve the following goals:

• Eliminate Reflection: Remove the dependency on Reflection within the database engine or dependency, leading to improved performance and reduced runtime overhead.

• Enhance CDI Lite Compatibility: Achieve compatibility with CDI Lite, making integrating Eclipse JNoSQL into CDI Lite-enabled environments easier.

Adopting the extension approach provides several benefits:

• Improved Performance: By eliminating Reflection, the Extension approach results in faster startup times and reduced runtime overhead, leading to better overall application performance.

• Seamless Transition: Since the same APIs are used, transitioning to the extension approach doesn’t require learning new APIs. Developers can continue using familiar APIs while enjoying the advantages of the new approach.

• CDI Lite Compatibility: The extension approach ensures that Eclipse JNoSQL works seamlessly with CDI Lite environments, allowing easy integration and taking advantage of CDI Lite’s features.

• Enhanced Maintainability: Java Annotation Processors simplify codebase maintenance and debugging by replacing reflection-based operations with compile-time checks and optimizations.

Extension Steps

To use this Extension, follow a two-step process:

Step 1: Remove Reflection Engine

Start by removing the reflection engine from the database engine or dependency. To do this, follow these steps:

1. Check the available databases at https://github.com/eclipse/jnosql-databases

2. Choose the database you intend to use.

3. Exclude the reflection engine dependency in your Maven project:

<dependency>
    <groupId>org.eclipse.jnosql.databases</groupId>
    <artifactId>chosen-database-artifact-id</artifactId>
    <version>chosen-database-version</version>
    <exclusions>
        <exclusion>
            <groupId>org.eclipse.jnosql.mapping</groupId>
            <artifactId>jnosql-mapping-reflection</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Step 2: Include Java Annotation Processor

After removing the reflection engine, include the Java Annotation Processor. There are two ways to do this:

1. Define the processor as a provided dependency:

<dependency>
    <groupId>org.eclipse.jnosql.lite</groupId>
    <artifactId>mapping-lite-processor</artifactId>
    <version>1.1.4</version>
    <scope>provided</scope>
</dependency>

1. Include the processor as a Maven plugin:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>17</source> <!-- depending on your project -->
                <target>17</target> <!-- depending on your project -->
                <annotationProcessorPaths>
                    <path>
                    <groupId>org.eclipse.jnosql.lite</groupId>
                    <artifactId>mapping-lite-processor</artifactId>
                    <version>1.1.4</version>
                    </path>
                    <!-- other annotation processors -->
                </annotationProcessorPaths>
            </configuration>
        </plugin>
    </plugins>
</build>

Usage and Limitations

With the Extension, you can now leverage Eclipse JNoSQL Lite’s benefits. However, be aware of the following limitations in the entity model:

• Java Record is not supported.

• A default constructor is required.

• All persistent fields with ID or Column annotations must have a getter and setter, at least in the default access modifier.

Warning

Keep in mind these limitations when designing and implementing your application.

Additionally, you can use Repositories from Jakarta Data, but note that certain limitations apply to entity modeling:

• There is no support for Sort in List or in Array.

• Graph and Key-Value Repositories do not support method by query.

Now you’re ready to explore the enhanced features of Eclipse JNoSQL Lite and leverage its benefits without relying on Reflection.

JNoSQL Static Metamodel

The JNoSQL Static Metamodel feature generates a Jakarta Data metamodel, facilitating type-safe access to entity attributes. This capability enhances compile-time safety, aids in refactoring, minimizes the use of "magic strings," and improves code documentation.

Installing the Metamodel Processor

To enable the generation of the static metamodel for your entities, include the Metamodel Processor in your project’s build configuration. This processor automatically generates metamodel classes corresponding to your entity classes, ensuring type-safe queries and operations. Add the following dependency to your Maven project:

<dependency>
    <groupId>org.eclipse.jnosql.metamodel</groupId>
    <artifactId>mapping-metamodel-processor</artifactId>
    <version>1.1.4</version>
    <scope>provided</scope>
</dependency>

With the metamodel classes generated, you can perform type-safe operations on your entities, such as querying, updating, or deleting records based on compile-time checked attributes.

Example Usage

Given an entity class, such as:

@Entity
public class Product {
    public long id;
    public String name;
    public float price;
}

You can use the statically generated metamodel to construct queries. For instance, to find products based on a dynamic search pattern and sort the results by price descending, name ascending, and ID ascending, you would use:

List<Product> found = products.findByNameLike(searchPattern, Order.by(
    _Product.price.desc(),
    _Product.name.asc(),
    _Product.id.asc()));

This approach ensures that query attribute references are both type-safe and refactor-safe, leading to more robust and maintainable code.

Bean Validation

Eclipse JNoSQL provide support for bean validation. It will validate before inserting/updating and constructing an entity.

<dependency>
    <groupId>org.eclipse.jnosql.mapping</groupId>
    <artifactId>jnosql-mapping-validation</artifactId>
    <version>1.1.4</version>
</dependency>

This requires the Jakarta Bean Validation specification.

@Entity
public class Car {

    @Column
    @NotNull
    @Pattern(regexp = "[A-Z]{3}-[0-9]{4}", message = "Invalid car plate")
    private String plate;

    @Column
    @NotNull
    @MonetaryMin(value = "100", message = "There is not car cheap like that")
    @MonetaryMax(value = "1000000", message = "The parking does not support fancy car")
    @CurrencyAccepted(currencies = "USD", message = "The car price must work with USD")
    @Convert(MonetaryAmountConverter.class)
    private MonetaryAmount price;

    @Column
    @NotBlank
    private String model;

    @Column
    @NotBlank
    private String color;
    ...
}

@Inject
Template template;
...
template.insert(new Car()); // invalid car

CriteriaQuery API

This is the experimental Criteria API, largely inspired by the JPA one. Using this API you can execute queries built via CriteriaQuery. The CriteriaQuery is used in combination with Metamodel Attributes. These attributes are automagically generated from the defined NoSQL Entities.

The Criteria API can be used via CriteriaDocumentTemplate.

Set dependency

  <dependency>
    <groupId>org.eclipse.jnosql.mapping</groupId>
    <artifactId>jnosql-metamodel-processor-extension</artifactId>
    <version>1.1.4</version>
    <optional>true</optional>
  </dependency>
  <dependency>
      <groupId>org.eclipse.jnosql.mapping</groupId>
      <artifactId>jnosql-criteria-extension</artifactId>
      <version>1.1.4</version>
  </dependency>

Driver for Jakarta Persistence entities

Provides a driver for Eclipse JNoSQL that supports Jakarta Persistence entities over a Jakarta Persistence provider. This project also contains a runner for the Jakarta Data TCK.

TCK Runners

The Eclipse JNoSQL project provides Technology Compatibility Kit (TCK) runners for Jakarta Data. These runners allow you to run the TCK tests against the Eclipse JNoSQL implementation to verify its compatibility with the Jakarta Data specifications.

Jakarta Data TCK Runner

The Jakarta Data TCK Runner is a project that runs the Jakarta Data TCK tests against the Eclipse JNoSQL implementation. It provides a convenient way to verify the compatibility of a Jakarta Data implementation with the Jakarta Data specification. Learn more about it here.

Getting Help

Having trouble with Eclipse JNoSQL extensions? We’d love to help!

Please report any bugs, concerns or questions with Eclipse JNoSQL extensions to https://github.com/eclipse/jnosql. Follow the instructions in the templates and remember to mention that the issue refers to JNoSQL extensions.

Contributing

We are very happy you are interested in helping us and there are plenty ways you can do so.

• Open an Issue: Recommend improvements, changes and report bugs. Please, mention that the issue refers to the JNoSQL extensions project.

• Open a Pull Request: If you feel like you can even make changes to our source code and suggest them, just check out our contributing guide to learn about the development process, how to suggest bugfixes and improvements.