311-frameworks-spring-jdbc

# 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 ## 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).