/311-frameworks-spring-jdbc

name: 311-frameworks-spring-jdbc
description: Use when you need to write or review programmatic JDBC with Spring — including JdbcClient (Spring Framework 7+) as the default API, JdbcTemplate only where batch/streaming APIs require JdbcOperations, NamedParameterJdbcTemplate for legacy named-param code, parameterized SQL, RowMapper mapping to records, batch operations, transactions, safe handling of generated keys, DataAccessException handling, read-only transactions, streaming large result sets, and @JdbcTest slice testing. This should trigger for requests such as Review Java code for Spring JDBC (JdbcTemplate, JdbcClient, NamedParameterJdbcTemplate); Apply best practices for Spring JDBC data access in Java code; Detect and fix SQL injection risks in JDBC code; Improve transaction boundaries or exception handling for JDBC operations; Review JdbcClient usage in Spring Framework 7. Part of Plinth Toolkit
license: Apache-2.0
metadata:
  author: Juan Antonio Breña Moral
  version: 0.18.0

Spring JDBC — JdbcClient (Spring Framework 7+)

Apply Spring JDBC guidelines with JdbcClient as the default; use JdbcTemplate / NamedParameterJdbcTemplate only for legacy code or APIs not covered by JdbcClient (batch updates, KeyHolder, RowCallbackHandler streaming).

**What is covered in this Skill?**

• Parameterized SQL (never concatenate user input)
• JdbcClient fluent API (Spring Framework 7+) — preferred for queries and updates
• Named parameters via JdbcClient; NamedParameterJdbcTemplate for legacy migration
• RowMapper, query(Class), and records
• Batch operations and generated keys (JdbcTemplate / JdbcOperations where needed)
• Safe handling of generated keys (KeyHolder; single-row JdbcClient updates)
• Service-layer @Transactional boundaries
• Read-only transactions (@Transactional(readOnly = true))
• Safe single-row access (optional() / findFirst() vs queryForObject)
• Streaming large result sets (RowCallbackHandler, ResultSetExtractor)
• DataAccessException handling (DuplicateKeyException, EmptyResultDataAccessException)
• @JdbcTest slice testing with @Sql fixtures

**Scope:** Apply recommendations based on the reference rules and good/bad code examples.

Constraints

Before applying any Spring JDBC changes, ensure the project compiles. If compilation fails, stop immediately. After applying improvements, run full verification.

• **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change
• **SAFETY**: If compilation fails, stop immediately
• **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements
• **SQL INJECTION**: Never concatenate untrusted input into SQL strings — always use bind parameters
• **BEFORE APPLYING**: Read the reference for detailed rules and good/bad patterns

When to use this skill

• Review Java code for Spring JDBC (JdbcTemplate, JdbcClient, NamedParameterJdbcTemplate)
• Apply best practices for Spring JDBC data access in Java code
• Detect and fix SQL injection risks in JDBC code
• Improve transaction boundaries or exception handling for JDBC operations
• Review JdbcClient usage in Spring Framework 7

Workflow

1. **Read reference and assess project context**

Read `references/311-frameworks-spring-jdbc.md` and inspect the current project setup before proposing changes.

2. **Gather scope and decide target improvements**

Identify requested outcomes, constraints, and the minimum safe set of changes to apply.

3. **Apply framework-aligned changes**

Implement or refactor configuration/code following the reference patterns and project conventions.

4. **Run verification and report results**

Execute appropriate build/tests and summarize what changed, what was verified, and any follow-up actions.

Reference

For detailed guidance, examples, and constraints, see [references/311-frameworks-spring-jdbc.md](references/311-frameworks-spring-jdbc.md).