Spring Boot和JPA:使用可选的远程标准实现搜索查询

Question

这是一个SSCCE,显示研究,不是一个骗局,是关于主题!

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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
}

我也有一个ProfileController,我希望公开一个GET端点,它提供了一种非常灵活/强大的搜索方式,可以Profiles根据大量标准进行搜索:

# 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);
    }
}

比方说,我的想法BigDecimalCriteria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null),我仍然坚持如何在以下内容中编写JPQL查询ProfileRepository:

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

如何以这样的方式实现@Query(...)for ProfileRepository#searchProfiles,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),并允许任何条件为null/optional？

当然,如果有任何漂亮的小库或者如果Spring Boot/JPA已经有了这个解决方案,我全都耳朵!

Answer 1

您可以通过JpaSpecificationExecutorspring数据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a结合使用JpaSpecificationExecutor.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仓库:

public interface PersonRepository extends JpaRepository<Person, Long>, JpaSpecificationExecutor<Person> {

}

正如您所看到的,我们扩展了另一个接口JpaSpecificationExecutor.此接口定义通过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Predicate包含查询的约束(在示例中,PersonSpecification正在执行查询select*from person where name =？or(surname =？and age =？)):

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);

这是github中的完整示例

您还可以使用规范创建任何复杂查询

Answer 2

在Querydsl和Web 支持Spring Data 扩展的帮助下，几乎你需要的东西已经在Spring Data 中实现了。

您也应该从以下扩展您的存储库QuerydslPredicateExecutor，如果您使用的是Spring Data REST，您可以使用基本过滤、分页和排序支持直接“从框中”查询您的存储库数据：

/profiles?isMale=0&heightMeters=1.7&sort=dob,desc&size=10&page=2

要实现更复杂的过滤器，您应该从 扩展您的存储库QuerydslBinderCustomizer并使用其customize方法（就在您的存储库中）。

例如，您可以为以下对象实现 'between' 过滤器heightMeters和 'like' 过滤器surname：

/profiles?isMale=0&heightMeters=1.7&sort=dob,desc&size=10&page=2

然后您可以查询您的个人资料：

/profiles?isMale=0&heightMeters=1.4&heightMeters=1.6&surename=doe

即 - 查找所有身高在 1.4 到 1.6 米之间并且确定名称包含“doe”的女性。

如果您不使用 Spring Data REST，您可以使用 QueryDSL 支持实现您自己的 rest 控制器方法：

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);        
    }
}

注意：不要忘记向您的项目添加 QueryDSL 依赖项：

/profiles?isMale=0&heightMeters=1.4&heightMeters=1.6&surename=doe

然后编译您的项目（例如mvn compile）以使其成为“Q”类。