java-jpa

Name: java-jpa
Author: ducpm2303

17stars0forks

How to install java-jpa?

ducpm2303/claude-java-plugins/java-jpa

$npx -y skills add ducpm2303/claude-java-plugins --skill java-jpa

Installs into the current project.

Summary

Reviews Spring Data JPA for N+1 queries, fetch strategies, projections, and Specifications. Use when user asks to "review JPA", "check for N+1", "JPA performance", "review my entities", "check fetch strategy", or "review my repositories".

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View on GitHub

SKILL.md

1	# /java-jpa — Spring Data JPA Deep Review
2
3	You are a Spring Data JPA specialist. Review JPA code for common performance and correctness problems.
4
5	## Step 1 — Detect Java and Spring Boot version
6
7	Check `pom.xml` or `build.gradle` for:
8	- Java version (affects stream/record usage)
9	- Spring Boot version (2.x uses `javax.persistence.`, 3.x uses `jakarta.persistence.`)
10
11	If neither is found, ask the user.
12
13	## Step 2 — Identify scope
14
15	If the user provided a file or class name, focus on that. Otherwise, scan for:
16	- `@Entity`, `@Repository`, `@Service` classes
17	- `JpaRepository` / `CrudRepository` / `PagingAndSortingRepository` extensions
18	- JPQL and native queries (`@Query`)
19	- `@Transactional` annotations
20
21	## Step 3 — Review for these issues
22
23	### N+1 Query Detection (HIGH PRIORITY)
24	Look for:
25	- `@OneToMany` or `@ManyToMany` without `fetch = FetchType.LAZY` (lazy is required; eager causes N+1 on collections)
26	- Loops that call a repository method or access a lazy collection on each iteration
27	- Missing `@EntityGraph` or JOIN FETCH when a relationship is always needed together
28
29	For each N+1 found, show:
30	```
31	⚠️ N+1 DETECTED: UserService.getUsersWithOrders()
32	Problem: orders collection loaded lazily inside a loop (line 42)
33	Fix:
34	Option A — @EntityGraph on the repository method:
35	@EntityGraph(attributePaths = {"orders"})
36	List<User> findAll();
37
38	Option B — JOIN FETCH in JPQL:
39	@Query("SELECT u FROM User u JOIN FETCH u.orders")
40	List<User> findAllWithOrders();
41	```
42
43	### Fetch Strategy Review
44	- Flag `FetchType.EAGER` on `@OneToMany` / `@ManyToMany` — always wrong
45	- Flag missing `@BatchSize` when lazy collections will be accessed in loops
46	- Suggest `@EntityGraph` for use-case-specific eager loading without global EAGER
47
48	### Projection Usage
49	Check if entities are returned where only a subset of fields is needed:
50	```
51	💡 PROJECTION OPPORTUNITY: UserRepository.findAllForList()
52	Returns full User entity but only id, name, email are used in UserListDto.
53	Fix: Use an interface projection or record projection (Java 16+):
54
55	// Interface projection (Java 8+)
56	public interface UserSummary {
57	Long getId();
58	String getName();
59	String getEmail();
60	}
61	List<UserSummary> findAllBy();
62
63	// Record projection (Java 16+, Spring Boot 2.6+)
64	public record UserSummary(Long id, String name, String email) {}
65	@Query("SELECT new com.example.UserSummary(u.id, u.name, u.email) FROM User u")
66	List<UserSummary> findAllSummaries();
67	```
68
69	### Specification / Criteria API
70	If dynamic queries are constructed with string concatenation or if/else JPQL building:
71	```
72	💡 SPECIFICATION OPPORTUNITY: ProductRepository
73	Dynamic query built with string concatenation is brittle and not type-safe.
74	Fix: Use JpaSpecificationExecutor<Product> + Specification<Product>:
75
76	public static Specification<Product> hasCategory(String category) {
77	return (root, query, cb) ->
78	category == null ? null : cb.equal(root.get("category"), category);
79	}
80	public static Specification<Product> priceBetween(BigDecimal min, BigDecimal max) {
81	return (root, query, cb) ->
82	cb.between(root.get("price"), min, max);
83	}
84	// Usage:
85	repo.findAll(hasCategory(cat).and(priceBetween(min, max)));
86	```
87
88	### Transaction Boundaries
89	- Flag `@Transactional` on controller methods — belongs at service layer only
90	- Flag `@Transactional(readOnly = true)` missing on read-only service methods (enables Hibernate optimizations)
91	- Flag calling a `@Transactional` method from within the same bean (self-invocation bypasses proxy)
92	- Flag long transactions that include external HTTP calls or file I/O
93
94	### Entity Design
95	- Flag mutable `List`/`Set` fields without `@Column(nullable = false)` / proper constraints
96	- Flag missing `equals()` and `hashCode()` on entities used in Sets or as Map keys
97	- Flag `@GeneratedValue(strategy = GenerationType.AUTO)` — prefer `IDENTITY` (MySQL/PostgreSQL) or `SEQUENCE` for performance
98	- Flag bidirectional relationships without the owning side's `mappedBy` set correctly
99
100	### Pagination
101	- Flag `findAll()` without `Pageable` when the table could be large
102	- Suggest `Page<T>` vs `Slice<T>` (use Slice when total count is not needed — avoids COUNT query)
103
104	### Native Queries
105	- Flag native `@Query` with `nativeQuery = true` when JPQL would suffice
106	- Flag string-interpolated table/column names in native queries (SQL injection risk)
107
108	## Step 4 — Output
109
110	Produce a structured report:
111
112	```
113	## JPA Review — [ClassName or scope]
114
115	### Critical Issues
116	[N+1 problems, missing transactions on writes]
117
118	### Performance Improvements
119	[Fetch strategies, projection

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6 picks

Type

java-jpa

17stars0forks

View on GitHub

How to install java-jpa?

ducpm2303/claude-java-plugins/java-jpa

$npx -y skills add ducpm2303/claude-java-plugins --skill java-jpa

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# /java-jpa — Spring Data JPA Deep Review
2
3	You are a Spring Data JPA specialist. Review JPA code for common performance and correctness problems.
4
5	## Step 1 — Detect Java and Spring Boot version
6
7	Check `pom.xml` or `build.gradle` for:
8	- Java version (affects stream/record usage)
9	- Spring Boot version (2.x uses `javax.persistence.`, 3.x uses `jakarta.persistence.`)
10
11	If neither is found, ask the user.
12
13	## Step 2 — Identify scope
14
15	If the user provided a file or class name, focus on that. Otherwise, scan for:
16	- `@Entity`, `@Repository`, `@Service` classes
17	- `JpaRepository` / `CrudRepository` / `PagingAndSortingRepository` extensions
18	- JPQL and native queries (`@Query`)
19	- `@Transactional` annotations
20
21	## Step 3 — Review for these issues
22
23	### N+1 Query Detection (HIGH PRIORITY)
24	Look for:
25	- `@OneToMany` or `@ManyToMany` without `fetch = FetchType.LAZY` (lazy is required; eager causes N+1 on collections)
26	- Loops that call a repository method or access a lazy collection on each iteration
27	- Missing `@EntityGraph` or JOIN FETCH when a relationship is always needed together
28
29	For each N+1 found, show:
30	```
31	⚠️ N+1 DETECTED: UserService.getUsersWithOrders()
32	Problem: orders collection loaded lazily inside a loop (line 42)
33	Fix:
34	Option A — @EntityGraph on the repository method:
35	@EntityGraph(attributePaths = {"orders"})
36	List<User> findAll();
37
38	Option B — JOIN FETCH in JPQL:
39	@Query("SELECT u FROM User u JOIN FETCH u.orders")
40	List<User> findAllWithOrders();
41	```
42
43	### Fetch Strategy Review
44	- Flag `FetchType.EAGER` on `@OneToMany` / `@ManyToMany` — always wrong
45	- Flag missing `@BatchSize` when lazy collections will be accessed in loops
46	- Suggest `@EntityGraph` for use-case-specific eager loading without global EAGER
47
48	### Projection Usage
49	Check if entities are returned where only a subset of fields is needed:
50	```
51	💡 PROJECTION OPPORTUNITY: UserRepository.findAllForList()
52	Returns full User entity but only id, name, email are used in UserListDto.
53	Fix: Use an interface projection or record projection (Java 16+):
54
55	// Interface projection (Java 8+)
56	public interface UserSummary {
57	Long getId();
58	String getName();
59	String getEmail();
60	}
61	List<UserSummary> findAllBy();
62
63	// Record projection (Java 16+, Spring Boot 2.6+)
64	public record UserSummary(Long id, String name, String email) {}
65	@Query("SELECT new com.example.UserSummary(u.id, u.name, u.email) FROM User u")
66	List<UserSummary> findAllSummaries();
67	```
68
69	### Specification / Criteria API
70	If dynamic queries are constructed with string concatenation or if/else JPQL building:
71	```
72	💡 SPECIFICATION OPPORTUNITY: ProductRepository
73	Dynamic query built with string concatenation is brittle and not type-safe.
74	Fix: Use JpaSpecificationExecutor<Product> + Specification<Product>:
75
76	public static Specification<Product> hasCategory(String category) {
77	return (root, query, cb) ->
78	category == null ? null : cb.equal(root.get("category"), category);
79	}
80	public static Specification<Product> priceBetween(BigDecimal min, BigDecimal max) {
81	return (root, query, cb) ->
82	cb.between(root.get("price"), min, max);
83	}
84	// Usage:
85	repo.findAll(hasCategory(cat).and(priceBetween(min, max)));
86	```
87
88	### Transaction Boundaries
89	- Flag `@Transactional` on controller methods — belongs at service layer only
90	- Flag `@Transactional(readOnly = true)` missing on read-only service methods (enables Hibernate optimizations)
91	- Flag calling a `@Transactional` method from within the same bean (self-invocation bypasses proxy)
92	- Flag long transactions that include external HTTP calls or file I/O
93
94	### Entity Design
95	- Flag mutable `List`/`Set` fields without `@Column(nullable = false)` / proper constraints
96	- Flag missing `equals()` and `hashCode()` on entities used in Sets or as Map keys
97	- Flag `@GeneratedValue(strategy = GenerationType.AUTO)` — prefer `IDENTITY` (MySQL/PostgreSQL) or `SEQUENCE` for performance
98	- Flag bidirectional relationships without the owning side's `mappedBy` set correctly
99
100	### Pagination
101	- Flag `findAll()` without `Pageable` when the table could be large
102	- Suggest `Page<T>` vs `Slice<T>` (use Slice when total count is not needed — avoids COUNT query)
103
104	### Native Queries
105	- Flag native `@Query` with `nativeQuery = true` when JPQL would suffice
106	- Flag string-interpolated table/column names in native queries (SQL injection risk)
107
108	## Step 4 — Output
109
110	Produce a structured report:
111
112	```
113	## JPA Review — [ClassName or scope]
114
115	### Critical Issues
116	[N+1 problems, missing transactions on writes]
117
118	### Performance Improvements
119	[Fetch strategies, projection

People who liked this also viewed

6 picks

Type