将可选参数传递给Spring Data Repository方法的@Query [英] Passing optional parameters to @Query of a Spring Data Repository method

问题描述

我在当前项目中使用Spring Data和Neo4j并处于以下情况:

I work with Spring Data and Neo4j in my current project and have the following situation:

@RestController
@RequestMapping(value = SearchResource.URI)
public class PersonResource {

public static final String URI = "/person";

@Autowired
PersonRepository personRepository;

@GetMapping
public Collection<Person> findPersons(
    @RequestParam(value = "name", required = false) String name,
    @RequestParam(value = "birthDate", required = false) Long birthDate,
    @RequestParam(value = "town", required = false) Spring town) {

    Collection<Person> persons;

    if (name != null && birthDate == null && town == null) {
        persons = personRepository.findPersonByName(name);
    } else if (name != null && birthDate != null && town == null {
        persons = personRepository.findPersonByNameAndBirthDate(name, birthDate);
    } else if (name != null && birthDate != null && town != null {
        persons = personRepository.findPersonByNameAndBirthDateAndTown(name, birthDate, town);
    } else if (name == null && birthDate != null && town == null {
        persons = findPersonByBirthDate(birthDate);
    } else if
        ...
    }
    return persons;
}
}

您可能已经看到我的问题:if-else-blocks链.每次我添加一个用于搜索人员的新过滤器时，都必须添加一个新的可选参数，将所有if-else-blocks都加倍，并向我的PersonRepository中添加新的find-Methods.所有的find方法都使用Spring @Query注释进行注释，并获得一个自定义的密码查询来获取数据.

You probably already can see my problem: the chain of if-else-blocks. Each time I add a new filter for searching for persons, I have to add new optional parameter, double all the if-else-blocks and add new find-Methods to my PersonRepository. All the find-Methods are annotated with Spring @Query annotation and get a custom cypher query to get the data.

是否可以以更优雅的方式实现此功能?在这种情况下，Spring Data是否提供任何支持?

Is it possible to implement this functionality in a more elegant way? Does Spring Data offer any support in such situation?

推荐答案

我使用带有Spring Data的QueryDSL解决了这个问题. baeldung.com 上有一个很好的教程. 使用QueryDSL，您的spring数据查询就是personRepository.findAll(predicate);.

I solved this problem using QueryDSL with Spring Data. There is a good tutorial on baeldung.com. With QueryDSL your spring data query is simply personRepository.findAll(predicate);.

您可以使用一个对象来表示多个请求参数，并将其类型声明为Optional<String> name;等.

You can use an object to represent the multiple request parameters and declare their type to be Optional<String> name; etc.

然后您可以构建谓词(假设您已按照链接教程中的说明进行了设置):

Then you can build the predicate (assuming you setup you stuff as in the linked tutorial):

Predicate predicate = new MyPredicateBuilder().with("name", ":", name.orElse(""))
.with("birthDate", ":", birthDate.orElse(""))
.with("town", ":", town.orElse(""))
.build();

我亲自对其进行了修改，因此它不使用:"，因为它们对我的使用是多余的.

I personally modified it so it didn't use the ":" as they are redundant for my usage.

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