Ujorm3: A New Lightweight ORM for JavaBeans and Records

Source: Dev.to

Why a New ORM?

The original JDBC API was never meant to be a full‑featured ORM, and over the years a plethora of libraries and frameworks have sprung up, each with its own trade‑offs in complexity, performance, and usability.

Ujorm 3 aims to be a reliable, safe, efficient, and easy‑to‑understand tool for relational‑database access:

• Thin layer over JDBC – no hidden magic.
• Stateless objects and native SQL – you stay in full control of what is sent to the database.
• No SQL‑dialect handling – write plain SQL; the library only adds type‑safe mapping helpers.
• No query‑result caching – only a small amount of metadata is retained for speed.

The first release candidate (RC1) is available on Maven Central under the Apache License 2.0.

Core Concepts

Example: Selecting Employees

// Static mapper – thread‑safe and reusable
static final ResultSetMapper EMPLOYEE_MAPPER =
        ResultSetMapper.of(Employee.class);

void select() {
    var sql = """
            SELECT ${COLUMNS}
            FROM employee e
            JOIN city c ON c.id = e.city_id
            LEFT JOIN employee b ON b.id = e.boss_id
            WHERE e.id > :employeeId
            """;

    var employees = SqlQuery.run(connection(), query -> query
            .sql(sql)
            // Map columns – the ${COLUMNS} placeholder is replaced automatically
            .column("e.id",   MetaEmployee.id)
            .column("e.name", MetaEmployee.name)
            .column("c.name", MetaEmployee.city, MetaCity.name)
            .column("c.country_code", MetaEmployee.city, MetaCity.countryCode)
            .column("b.name", MetaEmployee.boss, MetaEmployee.name)
            .bind("employeeId", 0L)
            // Convert the ResultSet stream to a List
            .streamMap(EMPLOYEE_MAPPER.mapper())
            .toList());
}

The domain class does not need prior registration.
If you prefer to keep the SQL text untouched, use label() instead of column(). **column() and label() cannot be mixed in the same query.

Benchmark Highlights

• Runtime‑generated mapping classes (instead of reflection) → lower memory usage, less GC pressure.
• Zero external dependencies → the compiled benchmark + Ujorm 3 JAR is:

org.ujorm
ujorm-orm
3.0.0-RC1

Generating the Metamodel (optional)

If you want the type‑safe Meta* classes, enable the annotation processor in the maven-compiler-plugin:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.11.0</version>
    <configuration>
        <annotationProcessorPaths>
            <path>
                <groupId>org.ujorm</groupId>
                <artifactId>ujorm-processor</artifactId>
                <version>3.0.0-RC1</version>
            </path>
        </annotationProcessorPaths>
    </configuration>
</plugin>

Summary

Ujorm 3 delivers a minimal‑overhead, transparent, and type‑safe way to work with relational databases in Java. By staying close to JDBC while providing a clean, modern API, it lets developers write clear, performant code without the hidden costs of heavyweight ORMs.

Give it a try in your next Java 17+ project and experience the simplicity of “the simplest thing that could possibly work.”

<dependency>
    <groupId>org.ujorm</groupId>
    <artifactId>ujorm-meta-processor</artifactId>
    <version>3.0.0-RC1</version>
</dependency>

The Ujorm module from the Benchmark project can be used as a template for a sample implementation. The library’s codebase is currently covered by JUnit tests that utilize an in‑memory H2 database (in addition to mocked objects).

Before releasing the final version, I plan to add integration tests for PostgreSQL, MySQL, Oracle, and MS SQL Server databases.

Note:
If you are working for a corporate client expecting standards or portability of abstractions between databases, use JPA/Hibernate instead. If you have already found an ORM framework that meets your expectations and needs, stick with it. However, if you are looking for a fast and transparent alternative without hidden mechanisms for your new project, the Ujorm 3 library is definitely worth a try.

Project Homepage

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More Examples as a JUnit Test

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Benchmark Tests

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