Add tutorial using composite Id with Data REST #252

rashidi · 2025-07-13T07:15:57Z

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Summary of Changes

Hello @rashidi, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new, self-contained tutorial demonstrating best practices for integrating Spring Data REST with entities that utilize composite primary keys. The changes encompass new entity definitions, custom ID converters, and comprehensive integration tests, providing a clear example for developers facing similar challenges.

Highlights

New Tutorial Project: I've added a new tutorial project, data-rest-composite-id, which demonstrates how to implement and expose entities with composite IDs through Spring Data REST.
Entity Modeling with Composite IDs: The tutorial showcases two entity types, Author and Book, both utilizing @EmbeddedId for their primary keys. Author uses a simple Long wrapped in an embedded Id class, while Book uses a more complex Isbn class that parses an ISBN string into its components.
Spring Data REST ID Conversion: To properly handle composite IDs in the REST API, I've implemented BackendIdConverter for both Author.Id and Book.Isbn. Additionally, an AuthorIdReferencedConverter is registered to manage conversions when referencing Author entities by their composite ID.
Comprehensive Testing: The new tutorial includes integration tests (CreateAuthorTests, CreateBookTests, GetBookTests) to validate the creation and retrieval of entities with composite IDs via the exposed REST endpoints, utilizing Testcontainers for a robust testing environment.
Documentation Updates: The main README.adoc and the project's navigation (docs/modules/ROOT/nav.adoc) have been updated to include the new 'Spring Data REST with Composite ID' tutorial, with a dedicated data-rest-composite-id.adoc file providing detailed explanations.

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Code Review

This pull request adds a new tutorial demonstrating how to use Spring Data REST with composite IDs. The changes include a new Spring Boot module with entities, repositories, converters, and tests, along with corresponding documentation.

The review identified several issues:

A mis-generated Liquibase file with duplicate changesets.
Potential NullPointerExceptions in equals, hashCode, and toString methods in the entity classes due to lack of null-safety.
A critical typo in a test configuration property.
Use of a shaded dependency in tests, which is not a best practice.

I've provided suggestions to fix these issues to improve code quality, correctness, and maintainability.

data-jdbc-schema-generation/user.yaml

gemini-code-assist · 2025-07-13T07:18:42Z

data-rest-composite-id/src/test/java/zin/rashidi/datarest/compositeid/book/GetBookTests.java

+ */
+@Import(TestcontainersConfiguration.class)
+@Testcontainers
+@SpringBootTest(webEnvironment = RANDOM_PORT, properties = "spring.jpa.hibernate.Ïddl-auto=create-drop")


There is a typo in the properties attribute. Ïddl-auto should be ddl-auto. The character Ï is a non-standard ASCII character that was likely inserted by mistake. This will cause the property to be ignored, which could lead to unexpected test behavior or failures.

Suggested change

@SpringBootTest(webEnvironment = RANDOM_PORT, properties = "spring.jpa.hibernate.Ïddl-auto=create-drop")

@SpringBootTest(webEnvironment = RANDOM_PORT, properties = "spring.jpa.hibernate.ddl-auto=create-drop")

gemini-code-assist · 2025-07-13T07:18:42Z

data-rest-composite-id/src/main/java/zin/rashidi/datarest/compositeid/book/Author.java

+        public final boolean equals(Object o) {
+            return o instanceof Id another && this.id.equals(another.id);
+       }
+
+        @Override
+        public int hashCode() {
+            return id.hashCode();
+        }


The equals and hashCode methods in the Id class can throw a NullPointerException if this.id is null. This can happen if an Author entity is new and has not yet been persisted. It's safer to use java.util.Objects to handle potential nulls.

Suggested change

public final boolean equals(Object o) {

return o instanceof Id another && this.id.equals(another.id);

}

@Override

public int hashCode() {

return id.hashCode();

}

@Override

public final boolean equals(Object o) {

return o instanceof Id another && java.util.Objects.equals(this.id, another.id);

}

@Override

public int hashCode() {

return java.util.Objects.hashCode(id);

}

data-rest-composite-id/src/main/java/zin/rashidi/datarest/compositeid/book/Book.java

gemini-code-assist · 2025-07-13T07:18:42Z

data-rest-composite-id/src/main/java/zin/rashidi/datarest/compositeid/book/Book.java

+        public String toString() {
+            return String.format("%d%d%d%d%d", prefix, group, registrant, publication, check);
+        }


The toString() method is susceptible to a NullPointerException because the %d format specifier in String.format does not handle null Integer values. This can happen if an Isbn object is created via the default constructor and its fields are not initialized. Using the %s specifier is a safer alternative as it handles nulls gracefully.

Suggested change

public String toString() {

return String.format("%d%d%d%d%d", prefix, group, registrant, publication, check);

}

@Override

public String toString() {

return String.format("%s%s%s%s%s", prefix, group, registrant, publication, check);

}

gemini-code-assist · 2025-07-13T07:18:42Z

...rest-composite-id/src/test/java/zin/rashidi/datarest/compositeid/book/CreateAuthorTests.java

+import org.springframework.context.annotation.Import;
+import org.springframework.test.web.servlet.assertj.MockMvcTester;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.shaded.org.apache.commons.lang3.math.NumberUtils;


Using a shaded dependency from Testcontainers (org.testcontainers.shaded.org.apache.commons.lang3.math.NumberUtils) is not recommended. Relying on shaded dependencies is risky as they might be changed or removed in future versions of Testcontainers without notice. It's better practice to declare a direct dependency on Apache Commons Lang3.

Suggested change

import org.testcontainers.shaded.org.apache.commons.lang3.math.NumberUtils;

import org.apache.commons.lang3.math.NumberUtils;

github-actions · 2025-07-13T10:46:14Z

Job Summary for Gradle

Gradle Build :: gradle-build

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
spring-boot-tutorials	build jacocoTestReport sonar	8.14.3	❌

github-actions · 2025-07-13T10:49:10Z

Job Summary for Gradle

Gradle Build :: gradle-build

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
spring-boot-tutorials	build jacocoTestReport sonar	8.14.3	❌

github-actions · 2025-07-13T10:53:22Z

Job Summary for Gradle

Gradle Build :: gradle-build

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
spring-boot-tutorials	build jacocoTestReport sonar	8.14.3	❌

sonarqubecloud · 2025-07-13T10:59:34Z

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
97.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

Add tutorial using composite Id with Data REST

183e8af

rashidi added the enhancement New feature or request label Jul 13, 2025

gemini-code-assist bot reviewed Jul 13, 2025

View reviewed changes

rashidi added 3 commits July 13, 2025 15:29

Add tutorial using composite Id with Data REST

e81614c

Add tutorial using composite Id with Data REST

0381f6c

Add tutorial using composite Id with Data REST

6cd85c7

Add tutorial using composite Id with Data REST

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Add tutorial using composite Id with Data REST

f906f62

rashidi added 3 commits July 13, 2025 18:55

Add tutorial using composite Id with Data REST

7bfc6cf

Add tutorial using composite Id with Data REST

0428921

Add tutorial using composite Id with Data REST

8aa7ba0

rashidi merged commit b4f8943 into master Jul 13, 2025
8 checks passed

rashidi deleted the data-rest/composite-key branch July 13, 2025 11:01

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	@SpringBootTest(webEnvironment = RANDOM_PORT, properties = "spring.jpa.hibernate.Ïddl-auto=create-drop")
	@SpringBootTest(webEnvironment = RANDOM_PORT, properties = "spring.jpa.hibernate.ddl-auto=create-drop")

	import org.testcontainers.shaded.org.apache.commons.lang3.math.NumberUtils;
	import org.apache.commons.lang3.math.NumberUtils;

Add tutorial using composite Id with Data REST #252

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Job Summary for Gradle

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