=============
后端_实体校验
=============

前端提交表单，后端收到POST请求，包体中包含Json格式的表单数据。

前端提交表单数据中的某项内容可能不符合实体类的要求，需要校验。

1 为实体类属性添加校验规则注解

/src/main/java/com/weihome/barblog/entity/User.java：

...
public class User implements Serializable {
    ...
    @NotBlank(message = "昵称不能为空")
    private String username;
    ...
    @NotBlank(message = "邮箱不能为空")
    @Email(message = "邮箱格式不正确")
    private String email;
    ...
}

2 添加实体校验异常处理

/src/main/java/com/weihome/barblog/common/GlobalExcepitonHandler.java：

...
public class GlobalExcepitonHandler {
    ...
    /**
     * 实体校验异常
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST) // 400
    @ExceptionHandler(value = MethodArgumentNotValidException.class)
    public Result handler(MethodArgumentNotValidException e) {
        log.error("实体校验异常", e);

        BindingResult bindingResult = e.getBindingResult();
        ObjectError objectError = bindingResult.getAllErrors()
            .stream().findFirst().get();

        return Result.error(objectError.getDefaultMessage());
    }
    ...
}

3 为控制器添加测试方法

/src/main/java/com/weihome/barblog/controller/UserController.java：

...
@RequestMapping("/user")
public class UserController {
    ...
    @PostMapping("/save")
    public Result save(@Validated @RequestBody User user) {
        return Result.ok(user);
    }
    ...
}

4 运行测试

执行BarblogApplication.main()...

Postman:
    POST
        localhost:8081/user/save
    Body
        raw/JSON
{
    "username": ""
}
----------------------------------
{
    "code": 400,
    "message": "昵称不能为空",
    "data": null
}

Postman:
    POST
        localhost:8081/user/save
    Body
        raw/JSON
{
    "username": "rabbit",
    "email": "weiyang8779#163.com"
}
----------------------------------
{
    "code": 400,
    "message": "邮箱格式不正确",
    "data": null
}

Postman:
    POST
        localhost:8081/user/save
    Body
        raw/JSON
{
    "username": "rabbit",
    "email": "weiyang8779@163.com"
}
----------------------------------
{
    "code": 200,
    "message": "操作成功",
    "data": {
        "id": null,
        "username": "rabbit",
        "avatar": null,
        "email": "weiyang8779@163.com",
        "password": null,
        "status": null,
        "created": null,
        "lastLogin": null
    }
}

5 为另一个实体类属性添加校验规则注解

/src/main/java/com/weihome/barblog/entity/Blog.java：

...
public class Blog implements Serializable {
    ...
    @NotBlank(message = "标题不能为空")
    private String title;
    ...
    @NotBlank(message = "摘要不能为空")
    private String description;
    ...
    @NotBlank(message = "内容不能为空")
    private String content;
    ...
}