{"id":7212,"date":"2021-05-19T23:01:39","date_gmt":"2021-05-20T03:01:39","guid":{"rendered":"https:\/\/springframework.guru\/?p=7212"},"modified":"2021-09-06T10:43:05","modified_gmt":"2021-09-06T14:43:05","slug":"requestbody-annotation","status":"publish","type":"post","link":"https:\/\/springframework.guru\/requestbody-annotation\/","title":{"rendered":"The @RequestBody Annotation"},"content":{"rendered":"

Spring Web applications and services need to process client requests sent over HTTP. When the HTTP clients send data with the request, the data is in the request body. On the application side, you need a mechanism to deserialize data sent in the request body to domain objects. This is done using the @RequestBody <\/code>annotation.<\/p>\n

In this post, I will explain how to use the @RequestBody <\/code> annotation.<\/p>\n

Deserializing RequestBody to Domain Object using @RequestBody <\/code>annotation<\/h2>\n

The @RequestBody <\/code> annotation is applicable to handler methods of Spring controllers. This annotation indicates that Spring should deserialize a request body into an object. This object is passed as a handler method parameter.<\/p>\n

Under the hood, the actual deserialization is done by one of the many implementations of MessageConverter<\/a>.<\/p>\n

To understand how this works, let\u2019s create a simple domain class to represent user credentials.<\/p>\n

The code of the User<\/code> domain class is this.<\/p>\n

User.java<\/h3>\n
package gur.springframework.model;\r\n\r\npublic class User {\r\nprivate String userName;\r\nprivate String password;\r\n\r\n    public User() {\r\n    }\r\n\r\n    public User(String userName, String password) {\r\n        this.userName = userName;\r\n        this.password = password;\r\n    }\r\n   \/\/Getter and Setter\r\n\r\n    public void setUserName(String userName) {\r\n        this.userName = userName;\r\n    }\r\n\r\n    public void setPassword(String password) {\r\n        this.password = password;\r\n    }\r\n\r\n    public String getUserName() {\r\n        return userName;\r\n    }\r\n\r\n    public String getPassword() {\r\n        return password;\r\n    }\r\n}\r\n<\/pre>\n
The code of the controller is this.<\/p>\n
DemoController.java<\/strong><\/p>\n
package gur.springframework.controller;\r\n\r\nimport gur.springframework.model.User;\r\nimport org.springframework.http.HttpStatus;\r\nimport org.springframework.web.bind.annotation.*;\r\n\r\n@RequestMapping(\"api\/v1\")\r\n@RestController\r\npublic class DemoController {\r\n\r\n    @PostMapping(\"users\")\r\n    @ResponseStatus(HttpStatus.CREATED)\r\n    public User registerUserCredential(@RequestBody User user){\r\n        System.out.println(\"User ID: \"+user.getUserName());\r\n        System.out.println(\"User ID: \"+user.getPassword());\r\n        return user;\r\n    }\r\n}\r\n<\/pre>\n
In the preceding controller class, the @RequestBody <\/code> annotation is specified on the registerUserCredential()<\/code> method. This annotation informs Spring to deserialize an incoming request body to the User domain object. The System.out.println<\/code> statements prints to console the user name and password of the deserialised User<\/code> object.<\/p>\n
You can send a POST request to invoke the registerUserCredential()<\/code> handler with the following URL:<\/p>\n
http:\/\/localhost:8080\/api\/v1\/users<\/code><\/p>\n
This figure shows a POST request sent from Postman.<\/p>\n
\"Post<\/a><\/p>\n
After sending the request, examine the console log. This figure shows the fields of the deserialized User<\/code> object.<\/p>\n
\"Fields<\/a><\/p>\n
The automated unit test code of the controller class is this.<\/p>\n
DemoControllerTest.java<\/strong><\/p>\n
package gur.springframework.controller;\r\n\r\n\r\nimport com.fasterxml.jackson.databind.ObjectMapper;\r\nimport gur.springframework.model.User;\r\nimport org.junit.jupiter.api.BeforeEach;\r\nimport org.junit.jupiter.api.Test;\r\nimport org.junit.jupiter.api.extension.ExtendWith;\r\nimport org.mockito.junit.jupiter.MockitoExtension;\r\nimport org.springframework.beans.factory.annotation.Autowired;\r\nimport org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;\r\nimport org.springframework.boot.test.context.SpringBootTest;\r\nimport org.springframework.http.MediaType;\r\nimport org.springframework.test.web.servlet.MockMvc;\r\nimport org.springframework.test.web.servlet.MvcResult;\r\nimport org.springframework.test.web.servlet.setup.MockMvcBuilders;\r\nimport static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;\r\nimport static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;\r\n\r\n@ExtendWith(MockitoExtension.class)\r\nclass DemoControllerTest {\r\n\r\n  private  MockMvc mockMvc;\r\n  private User user;\r\n\r\n    @BeforeEach\r\n    void setUp() {\r\n        user = new User(\"John\",\"pass1234\");\r\n\r\n         mockMvc = MockMvcBuilders\r\n                .standaloneSetup(DemoController.class)\r\n                .build();\r\n    }\r\n\r\n@Test\r\n    void registerUserCredential()throws Exception {\r\n\r\n    MvcResult result =    mockMvc.perform(post(\"\/api\/v1\/users\")\r\n            .contentType(MediaType.APPLICATION_JSON_VALUE)\r\n            .content(asJsonString(user)))\r\n            .andExpect(status().isCreated())\r\n            .andReturn();\r\n    String content = result.getResponse().getContentAsString();\r\n    System.out.println(content);\r\n\r\n}\r\n    public static String asJsonString(final Object obj) {\r\n        try {\r\n            return new ObjectMapper().writeValueAsString(obj);\r\n        } catch (Exception e) {\r\n            throw new RuntimeException(e);\r\n        }\r\n    }\r\n}\r\n<\/pre>\n
Deserializing RequestBody to Map using @RequestBody <\/code>annotation<\/h2>\n
You can also use the @RequestBody <\/code> annotation to deserialize a request body to a Java Map<\/code>.<\/p>\n
As a programmer, you don\u2019t need to do anything special. You only need to pass a Map<\/code> parameter to the handler method. It is @RequestBody <\/code> along with HttpMessageConverter<\/code> who will deserialize the JSON in the request body to the Map<\/code>.<\/p>\n
The code is this.<\/p>\n
@PostMapping(\"\/map\/users\")\r\n@ResponseStatus(HttpStatus.CREATED)\r\npublic Map<String, String> registerUserCredentialThroughMap(@RequestBody Map<String, String> userMap){\r\n    System.out.println(\"User ID: \"+userMap.get(\"userName\"));\r\n    System.out.println(\"User ID: \"+userMap.get(\"password\"));\r\n    return userMap;\r\n}\r\n<\/pre>\n
Once you run the application, access it using this URL from Postman.<\/p>\n
http:\/\/localhost:8080\/api\/v1\/map\/users<\/code><\/p>\n
As a result, you can see the deserialized map values on the console as shown in this figure.<\/p>\n
\"Fields<\/a><\/p>\n
The @RequestBody <\/code> annotation comes with the required<\/code> attribute that defaults to true<\/code>.\u00a0 Above all, this enforces that a request always contains body content. If not so, an exception is thrown. You can switch this to false<\/code> if you prefer null to be passed when the body content is null.<\/p>\n
The code to do so is this.<\/p>\n
@PostMapping(\"users\")\r\n    @ResponseStatus(HttpStatus.CREATED)\r\n    public User registerUserCredential(@RequestBody User user, required=\u201dfalse\u201d)\r\n<\/pre>\n
The @RequestBody <\/code> annotation is also commonly used with the @Valid<\/code> annotation. Both together perform validation of request data. You can read more about it in my post- Bean Validation in Spring Boot<\/a><\/p>\n
You can find the source code of this post on Github<\/a>.<\/p>\n
For in-depth knowledge of the Spring Framework and Spring Boot, you can check my Udemy Best Seller Course Spring Framework 5: Beginner to Guru<\/a><\/p>\n
\"Spring<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
Spring Web applications and services need to process client requests sent over HTTP. When the HTTP clients send data with the request, the data is in the request body. On the application side, you need a mechanism to deserialize data sent in the request body to domain objects. This is done using the @RequestBody annotation. […]Continue reading<\/a><\/p>\n","protected":false},"author":111,"featured_media":4590,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[21,104,182,34,354],"tags":[358,359],"class_list":["post-7212","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-spring","category-spring-boot","category-spring-framework-5","category-spring-mvc","category-spring-rest","tag-requestbody","tag-request-body-annotation"],"jetpack_publicize_connections":[],"aioseo_notices":[],"modified_by":"jt","jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/springframework.guru\/wp-content\/uploads\/2015\/03\/Banner560x292_06aweb.jpg","jetpack_shortlink":"https:\/\/wp.me\/p5BZrZ-1Sk","_links":{"self":[{"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/posts\/7212"}],"collection":[{"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/users\/111"}],"replies":[{"embeddable":true,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/comments?post=7212"}],"version-history":[{"count":11,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/posts\/7212\/revisions"}],"predecessor-version":[{"id":8153,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/posts\/7212\/revisions\/8153"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/media\/4590"}],"wp:attachment":[{"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/media?parent=7212"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/categories?post=7212"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/springframework.guru\/wp-json\/wp\/v2\/tags?post=7212"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}