spring-data-rest - 使集合属性呈现为关系而不是 json HAL 表示中的属性

Question

我得到了 hal 格式的响应，如下所示:

{
  "name": "Publisher A",
  "bookPublishers": [
    {
      "publishedDate": "2019-07-12T08:19:04.583+0000",
      "_links": {
        "publisher": {
          "href": "http://localhost:8080/api/publishers/1"
        },
        "book": {
          "href": "http://localhost:8080/api/books/2"
        }
      }
    },
    {
      "publishedDate": "2019-07-12T08:19:04.564+0000",
      "_links": {
        "publisher": {
          "href": "http://localhost:8080/api/publishers/1"
        },
        "book": {
          "href": "http://localhost:8080/api/books/1"
        }
      }
    }
  ],
  "_links": {
    "self": {
      "href": "http://localhost:8080/api/publishers/1"
    },
    "publisher": {
      "href": "http://localhost:8080/api/publishers/1"
    },
    "friends": {
      "href": "http://localhost:8080/api/publishers/1/friends"
    },
    "createdBy": {
      "href": "http://localhost:8080/api/publishers/1/contact"
    }
  }
}

我在 friend 链接中看到了bookPublishers属性。恕我直言，它们应该都是关联链接(请参阅 2.4. Creating the Associations )我可以在哪里“放置”其他资源。

我想让 spring 渲染 bookPublishers 和 friend 一样。

示例项目在这里:https://github.com/luvarqpp/poc-springHalRelations

你可以这样做:

git clone https://github.com/luvarqpp/poc-springHalRelations.git
cd poc-springHalRelations
mvn clean spring-boot:run

然后打开http://localhost:8080/api

PS:额外的问题，为业务逻辑提供自己的关系的最简单方法是什么，例如关系“renameAuthor”。

Answer 1

对于集合关系，当相关类型的存储库存在时，Spring Data 将提供一个链接。如果不存在存储库，则该集合将内嵌在响应中，否则客户端将如何获取数据。

因此，请为您的 BookPublisher 类型创建一个存储库。

相关documentation部分引用:

the component responsible for creating the links to referenced entities (such as those objects under the _links property in the object’s JSON representation). It takes an @Entity and iterates over its properties, creating links for those properties that are managed by a Repository and copying across any embedded or simple properties.

您还可以创建一个投影，以便在需要时嵌入数据。客户端可以在请求中指定此投影，从而防止额外的服务器调用。

例如

/publisher/1?projection=withBookPublishers。

https://docs.spring.io/spring-data/rest/docs/current/reference/html/#projections-excerpts.projections