使用Spring JPA规范进行多列搜索 [英] Multi-Column Search with Spring JPA Specifications

问题描述

我想在Spring-Boot后端中创建一个多字段搜索.如何使用Specification<T>做到这一点?

I want to create a multi field search in a Spring-Boot back-end. How to do this with a Specification<T> ?

环境

Springboot
Hibernate
Gradle
Intellij

前端的UI是Jquery Datatable.每列允许应用一个字符串搜索词. 将一栏以上的搜索字词连在一起.

The UI in the front end is a Jquery Datatable. Each column allows a single string search term to be applied. The search terms across more than one column is joined by a and.

我已经将来自前端的过滤器填充到Java对象中.

I have the filters coming from the front end already getting populated into a Java object.

第1步 扩展JPA规范执行器

Step 1 Extend JPA Specification executor

public interface SomeRepository extends JpaRepository<Some, Long>, PagingAndSortingRepository<Some, Long>, JpaSpecificationExecutor {

第二步 创建一个新类SomeSpec

Step2 Create a new class SomeSpec

在这里，我迷失了代码的外观以及它的工作方式.

This is where I am lost as to what the code looks like it and how it works.

每个列都需要一个方法吗? 什么是根，什么是Criteria Builder? 还需要什么?

Do I need a method for each column? What is Root and what is Criteria Builder? What else is required?

我在JPA还是个新手，所以虽然我不需要任何人为我编写代码，但详细的解释会很好.

I am rather new at JPA so while I don't need anyone to write the code for me a detailed explanation would be good.

更新 看来QueryDSL是解决此问题的更简单更好的方法.我正在使用Gradle.我是否需要从

UPDATE It appears QueryDSL is the easier and better way to approach this. I am using Gradle. Do I need to change my build.gradle from this ?

推荐答案

您可以考虑使用Spring Data对QueryDSL的支持，因为无需编写大量代码即可获得很多好处，即您实际上不必编写规范

You could consider using Spring Data's support for QueryDSL as you would get quite a lot without having to write very much code i.e. you would not actually have to write the specifictions.

请参阅此处以获取概述:

See here for an overview:

https://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/

尽管这种方法确实很方便(您甚至不必 编写一行实现代码以获取查询 执行)有两个缺点:首先，查询方法数量众多 可能会因为以下原因而在更大的应用程序中增长-这是第二个 点-查询定义了一组固定的条件.为了避免这些 有两个缺点，如果您能提出一套 您可以动态组合以建立自己的原子谓词 查询?

Although this approach is really convenient (you don’t even have to write a single line of implementation code to get the queries executed) it has two drawbacks: first, the number of query methods might grow for larger applications because of - and that’s the second point - the queries define a fixed set of criterias. To avoid these two drawbacks, wouldn’t it be cool if you could come up with a set of atomic predicates that you could combine dynamically to build your query?

因此，您的存储库实质上就是:

So essentially your repository becomes:

public interface SomeRepository extends JpaRepository<Some, Long>,
     PagingAndSortingRepository<Some, Long>, QueryDslPredicateExecutor<Some>{

}

您还可以在Controller中获得自动绑定到谓词的请求参数:

You can also get request parameters automatically bound to a predicate in your Controller:

在这里看到:

您的控制器看起来像这样:

SO your Controller would look like:

  @Controller
  class SomeController {

    private final SomeRepository repository;

    @RequestMapping(value = "/", method = RequestMethod.GET)
    String index(Model model,
                 @QuerydslPredicate(root = Some.class) Predicate predicate,
                 Pageable pageable) {

      model.addAttribute("data", repository.findAll(predicate, pageable));
      return "index";
    }
  }

因此，有了上述内容，这仅仅是在项目上启用QueryDSL的一种情况，并且UI现在应该能够通过各种条件组合来过滤，排序和分页数据.

So with the above in place it is simply a Case of enabling QueryDSL on your project and the UI should now be able to filter, sort and page data by various combinations of criteria.

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