java - 使用 Spring WebFlux 路由器功能时如何获取模型属性?
问题描述
Spring WebFlux提供了两种编程选项的选择:Annotated Controllers和Functional Endpoints。对于第一个,我们可以使用@ModelAttribute
注解将模型属性从控制器传递到视图(例如Thymeleaf html-template),反之亦然。但是,当涉及到路由器功能时,到目前为止,我只是想出了如何将模型属性附加到ServerResponse
,但找不到将它们取回的方法。考虑以下代码片段:
@Configuration
public class StudentsRouterFunctions {
// inject repository
private final StudentsCrudRepository repo;
public StudentsRouterFunctions(StudentsCrudRepository repo) {
this.repo = repo;
}
@Bean
RouterFunction<?> routs() {
return RouterFunctions.route()
.GET("/students", this::showStudents)
.POST("/students", this::saveStudent)
.build();
}
// #1: GET-handler
private Mono<ServerResponse> showStudents(ServerRequest request) {
// set model attributes
Map<String, Object> model = new HashMap<>();
Mono<Student> studentsList = repo.findAll().collectList();
Mono<Student> newStudent = Mono.just(new Student());
model.put("students", studentsList);
model.put("studentForm", newStudent);
// render the view
return ServerResponse.ok()
.contentType(MediaType.TEXT_HTML)
.render("students-template", model);
}
// #2: POST-handler
private Mono<ServerResponse> saveStudent(ServerRequest request) {
// and here I somehow need to get my new student object
// back from the view via "studentForm" model attribute
// Student newStudent = request.getModel().get("studentForm");
// !!! however, ServerRequest.getModel() method doesn't exist
return repo.save(newStudent)
.then(ServerResponse.status(HttpStatus.PERMANENT_REDIRECT)
.render("redirect:/students", new Object()));
}
解决方案
没有任何ServerRequest::getModel
方法ServerRequest::bodyToMono(Class)
可以提取模型所在的主体Mono<T>
。
然后利用响应式存储库的方法ReactiveCrudRepository::save
返回类型的优势,Mono<T>
使用Mono::flatMap
.
我还没有测试过,但它应该可以工作。
private Mono<ServerResponse> saveStudent(ServerRequest request) {
return request.bodyToMono(Student.class) // Mono<Student> (a new one)
.flatMap(repo::save) // Mono<Student> (a saved one)
.then(ServerResponse // redirect sequence
.status(HttpStatus.PERMANENT_REDIRECT)
.render("redirect:/students", new Object()));
}
// .flatMap(repo::save) is the same as .flatMap(newStudent -> repo.save(newStudent))
请注意,该方法Mono::then
会丢弃源中的元素,因此重定向的对象仍保留为new Object()
,因此您要使用Mono::map
.
private Mono<ServerResponse> saveStudent(ServerRequest request) {
return request.bodyToMono(Student.class) // Mono<Student> (a new one)
.flatMap(repo::save) // Mono<Student> (a saved one)
.map(savedStudent -> ServerResponse // redirect sequence
.status(HttpStatus.PERMANENT_REDIRECT)
.render("redirect:/students", savedStudent));
}