这是一个SSCCE，展示了研究，不是一个骗局，而且是主题!!!
Spring Boot REST服务和MySQL。我有以下Profile实体：
@Entity
@Table(name = "profiles")
public class Profile extends BaseEntity {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "profile_given_name")
private String givenName;
@Column(name = "profile_surname")
private String surname;
@Column(name = "profile_is_male")
private Integer isMale;
@Column(name = "profile_height_meters", columnDefinition = "DOUBLE")
private BigDecimal heightMeters;
@Column(name = "profile_weight_kilos", columnDefinition = "DOUBLE")
private BigDecimal weightKilos;
@Column(name = "profile_dob")
private Date dob;
// Getters, setters & ctor down here
}
我还有一个ProfileController，我希望公开一个GET端点，它提供了一种非常灵活/健壮的方式来根据大量标准搜索Profiles：
# Search for women between 1.2 and 1.8 meters tall.
GET /v1/profiles?isMale=0&heightMeters={"gt": 1.2, "lt": 1.8}
# Search for men born after Jan 1, 1990 who weigh less than 100 kg.
GET /v1/profiles?isMale=1&dob={"gt" : "1990-01-01 00:00:00"}&weightKilos={"lt": 100.0}
等
所以这是我的控制器：
@RestController
@RequestMapping("/v1/profiles")
public class ProfileResource {
@Autowired
ProfileRepository profileRepository;
@GetMapping
public ResponseEntity<Set<Profile>> searchProfiles(@RequestParam(value = "isMale", required = false) String isMaleVal,
@RequestParam(value = "heightMeters", required = false) String heightMetersVal,
@RequestParam(value = "weightKilos", required = false) String weightKilosVal,
@RequestParam(value = "dob", required = false) String dobVal) {
Integer isMaleVal;
BooleanCriteria isMaleCriteria;
if(isMaleVal != null) {
// Parse the value which could either be "0" for female, "1" for male or something like
// ?isMale={0,1} to indicate
// BooleanCriteria would store which values male, female or both) to include in the search
}
BigDecimal heighMeters;
BigDecimalCriteria heightCriteria;
if(heightMetersVal != null) {
// Parse the value which like in the examples could be something like:
// ?heightMeters={"gt" : "1.0"}
// BigDecimalCriteria stores range information
}
BigDecimal heighMeters;
BigDecimalCriteria weightCriteria;
if(weightKilosVal != null) {
// Parse the value which like in the examples could be something like:
// ?weightKilos={"eq" : "100.5"}
// BigDecimalCriteria stores range information
}
// Ditto for DOB and DateCriteria
// TODO: How to pack all of these "criteria" POJOs into a
// CrudRepository/JPQL query against the "profiles" table?
Set<Profile> profiles = profileRepository.searchProfiles(
isMaleCriteria, heightCriteria, weightCriteria, dobCriteria);
}
}
我想，BigDecimalCriteria就像是：
// Basically it just stores the (validated) search criteria that comes in over the wire
// on the controller method
public class BigDecimalCriteria {
private BigDecimal lowerBound;
private Boolean lowerBoundInclusive;
private BigDecimal upperBound;
private Boolean upperBoundInclusive;
// Getters, setters, ctors, etc.
}
由于所有这些搜索条件都是可选的（因此可以是null），我仍然坚持如何在ProfileRepository中编写JPQL查询：
public interface ProfileRepository extends CrudRepository<Profile,Long> {
@Query("???")
public Set<Profile> searchProfiles();
}
如何以@Query(...) ProfileRepository#searchProfiles实现{{1}}以启用我的所有搜索条件（给定所有允许的范围和条件值进行搜索），并允许任何标准为空/可选？
当然，如果有任何漂亮的小库或者如果Spring Boot / JPA已经有了这方面的解决方案，我全心全意！
答案 0 :(得分：13)
您可以在弹簧数据中通过JpaSpecificationExecutor实现具有规范的复杂查询。
存储库接口必须扩展JpaSpecificationExecutor<T>接口，以便我们可以通过创建新的Specification<T>对象来指定数据库查询的条件。
诀窍在于将规范界面与JpaSpecificationExecutor结合使用。
这是一个例子：
@Entity
@Table(name = "person")
public class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name = "name")
private String name;
@Column(name = "surname")
private String surname;
@Column(name = "city")
private String city;
@Column(name = "age")
private Integer age;
....
}
然后我们定义我们的存储库：
public interface PersonRepository extends JpaRepository<Person, Long>, JpaSpecificationExecutor<Person> {
}
正如您所看到的，我们已经扩展了JpaSpecificationExecutor的另一个界面。此接口定义了通过Specification类执行搜索的方法。
我们现在要做的是定义我们的规范，它将返回包含查询约束的Predicate（在示例中，PersonSpecification正在执行查询select * from person where name = ？或（姓氏=？和年龄=？））：
public class PersonSpecification implements Specification<Person> {
private Person filter;
public PersonSpecification(Person filter) {
super();
this.filter = filter;
}
public Predicate toPredicate(Root<Person> root, CriteriaQuery<?> cq,
CriteriaBuilder cb) {
Predicate p = cb.disjunction();
if (filter.getName() != null) {
p.getExpressions()
.add(cb.equal(root.get("name"), filter.getName()));
}
if (filter.getSurname() != null && filter.getAge() != null) {
p.getExpressions().add(
cb.and(cb.equal(root.get("surname"), filter.getSurname()),
cb.equal(root.get("age"), filter.getAge())));
}
return p;
}
}
现在是时候使用它了。以下代码片段显示了如何使用我们刚刚创建的规范：
...
Person filter = new Person();
filter.setName("Mario");
filter.setSurname("Verdi");
filter.setAge(25);
Specification<Person> spec = new PersonSpecification(filter);
List<Person> result = repository.findAll(spec);
Here是github中的完整示例
您还可以使用规范
创建任何复杂查询答案 1 :(得分：4)
Almost what you need is already implemented in Spring Data with help of Querydsl and Web support Spring Data extensions.
You should extend your repo as well from QuerydslPredicateExecutor and, if you are using Spring Data REST, you can query your repo data right 'from the box' with base filtering, paging and sorting support:
/profiles?isMale=0&heightMeters=1.7&sort=dob,desc&size=10&page=2
To implement more complex filter you should extend your repo from the QuerydslBinderCustomizer and use its customize method (right in your repo).
For example you can implement 'between' filter for heightMeters and 'like' filter for surname:
public interface ProfileRepository extends JpaRepository<Profile, Long>, QuerydslPredicateExecutor<Profile>, QuerydslBinderCustomizer<QProfile> {
@Override
default void customize(QuerydslBindings bindings, QProfile profile) {
bindings.excluding( // used to exclude unnecessary fields from the filter
profile.id,
profile.version,
// ...
);
bindings.bind(profile.heightMeters).all((path, value) -> {
Iterator<? extends BigDecimal> it = value.iterator();
BigDecimal from = it.next();
if (value.size() >= 2) {
BigDecimal to = it.next();
return path.between(from, to)); // between - if you specify heightMeters two times
} else {
return path.goe(from); // or greter than - if you specify heightMeters one time
}
});
bindings.bind(profile.surname).first(StringExpression::containsIgnoreCase);
}
}
Then you can query your profiles:
/profiles?isMale=0&heightMeters=1.4&heightMeters=1.6&surename=doe
i.e. - find all females which height is between 1.4 and 1.6 meters and surename contains 'doe'.
If you are not using Spring Data REST you can implement your own rest controller method with QueryDSL support:
@RestController
@RequestMapping("/profiles")
public class ProfileController {
@Autowired private ProfileRepository profileRepo;
@GetMapping
public ResponseEntity<?> getAll(@QuerydslPredicate(root = Profile.class, bindings = ProfileRepository.class) Predicate predicate, Pageable pageable) {
Page<Profile> profiles = profileRepo.findAll(predicate, pageable);
return ResponseEntity.ok(profiles);
}
}
Note: don't forget to add QueryDSL dependency to you project:
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<scope>provided</scope>
</dependency>
<build>
<plugins>
<plugin>
<groupId>com.mysema.maven</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.1.3</version>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
<configuration>
<outputDirectory>target/generated-sources/annotations</outputDirectory>
<processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
Then compile your project (for example mvn compile) to let it make 'Q' classes.
答案 2 :(得分：3)
答案非常简单，你可以在春天使用query-by-example。
甚至更多，您不需要列出控制器中的所有Profile属性，只需将Profile作为参数，spring将负责处理。
正如你想要验证请求参数，这里更容易与bean验证器集成，采取＆＃34; givenName＆＃34;举个例子。在实体中添加NotNull，并在控制器中添加@Valid，以防＆＃34; givenName＆＃34;不在请求参数中，您将收到＆＃34;错误请求＆＃34;响应。
以下是工作代码：
@Entity
@Table(name = "profiles")
public class Profile {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "profile_given_name")
@NotNull
private String givenName;
@Column(name = "profile_surname")
private String surname;
@Column(name = "profile_is_male")
private Integer isMale;
@Column(name = "profile_height_meters", columnDefinition = "DOUBLE")
private BigDecimal heightMeters;
@Column(name = "profile_weight_kilos", columnDefinition = "DOUBLE")
private BigDecimal weightKilos;
@Column(name = "profile_dob")
private Date dob;
}
<强> ProfileResource
@RestController
@RequestMapping("/v1/profiles")
public class ProfileResource {
@Autowired
ProfileRepository profileRepository;
@GetMapping
public ResponseEntity<List<Profile>> searchProfiles(@Valid Profile profile) {
List<Profile> all = profileRepository.findAll(Example.of(profile));
return ResponseEntity.ok(all);
}
}
<强> ProfileRepository
public interface ProfileRepository extends JpaRepository<Profile, Long> {
}
然后根据需要发送GET /v1/profiles?isMale=0 HTTP方法。
答案 3 :(得分：0)
在弹簧数据中查看“按示例查询”。似乎符合你需要的账单...
https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#query-by-example