Spring Boot 和 JPA：使用可选的范围条件实现搜索查询

Question

这是一个 SSCCE ，显示研究，不是骗子而且是主题！！！

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Spring Boot REST 服务和 MySQL 在这里。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 并且我想公开一个 GET 端点，它提供了一种非常灵活/稳健的方式来搜索 Profiles 基于大量标准：

 # 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);
    }
}

我对 BigDecimalCriteria 的想法是这样的：

 // 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 ），我被困在如何在 ProfileRepository 中编写 JPQL 查询：

 public interface ProfileRepository extends CrudRepository<Profile,Long> {
  @Query("???")
  public Set<Profile> searchProfiles();
}

如何实现 @Query(...) 用于 ProfileRepository#searchProfiles 以启用我的所有搜索条件（给定所有允许的范围和要搜索的条件值），并允许任何条件为空/可选？

当然，如果有任何漂亮的小库或者 Spring Boot/JPA 已经有解决方案，我全都听好了！

原文由 smeeb 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

可以通过spring data中的 JpaSpecificationExecutor 实现有规范的复杂查询。存储库接口必须扩展 JpaSpecificationExecutor<T> 接口，因此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。

诀窍在于将规范接口与 JpaSpecificationExecutor 结合使用。这是示例：

 @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> {

}

如您所见，我们扩展了另一个接口 JpaSpecificationExecutor 。该接口定义了通过规范类执行搜索的方法。

我们现在要做的是定义我们的规范，它将返回 Predicate 包含查询的约束（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。下面的代码片段展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);

这 是github中的完整示例

您还可以使用规范创建任何复杂的查询

原文由 Bhushan Uniyal 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

答案非常简单，您可以在 spring 中使用 示例查询。

更重要的是，您不需要列出控制器中的所有 Profile 属性，您只需将 Profile 作为参数，spring 会处理它。

并且由于您要验证请求参数，这里更容易与 bean 验证器集成，以“givenName”为例。在实体中添加 NotNull @Valid ，并在控制器中添加—，如果“givenName”不在请求参数中，您将得到“错误请求”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;
}

档案资源

@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);
    }
}

配置文件库

public interface ProfileRepository extends JpaRepository<Profile, Long> {
}

然后根据需要发送 GET /v1/profiles?isMale=0 HTTP 方法。

原文由 Liping Huang 发布，翻译遵循 CC BY-SA 3.0 许可协议