1
1
.
.
1
1
.
.
3
3
V
V
a
a
l
l
i
i
d
d
a
a
t
t
e
e
-
-
D
D
T
T
O
O
-
-
F
F
r
r
o
o
m
m
J
J
S
S
O
O
N
N
I
I
n
n
f
f
o
o
[
[
G
G
]
]
[
[
R
R
]
]
This tutorial shows how to Validate User Input during Deserialization of JSON into DTO.
Validation checks if JSON contains all parameters and if they have proper value.
Application Schema [Results]
Spring Boot Starters
GROUP
DEPENDENCY
DESCRIPTION
Web
Spring Web
Enables: @Controller, @RequestMapping, Tomcat Server
P
P
r
r
o
o
c
c
e
e
d
d
u
u
r
r
e
e
Create Project: springboot_dto_json_validate (add Spring Boot Starters from the table)
Edit File: pom.xml (add validation dependency)
Create Package: DTO (inside main package)
– Create Class: PersonDTO.java (inside package DTO)
Create Package: controllers (inside main package)
– Create Class: MyController.java (inside package controllers)
pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
PersonDTO.java
package com.ivoronline.springboot_dto_json_validate.DTO;
import org.springframework.stereotype.Component;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
@Component
public class PersonDTO {
@NotBlank(message = "Name is mandatory") //@NotBlank()
@Size(min=5, max=30) //characters
public String name;
@NotNull //"must not be null"
@Min(value = 18, message = "Minimum value for Age is 18") //@Min(18)
public Integer age;
}
MyController
PersonDTO
Postman
HTTP POST Request
http://localhost:8080/addPerson
{ "name": "John", "age": "20" }
MyController.java
package com.ivoronline.springboot_dto_json_validate.controllers;
import com.ivoronline.springboot_dto_json_validate.DTO.PersonDTO;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.validation.FieldError;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;
import javax.validation.Valid;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@Controller
public class MyController {
//==================================================================
// ADD PERSON
//==================================================================
@ResponseBody
@RequestMapping("/AddPerson")
public String addPerson(@Valid @RequestBody PersonDTO personDTO) {
return "Person added";
}
//==================================================================
// HANDLE EXCEPTIONS
//==================================================================
@ResponseBody
@ResponseStatus(HttpStatus.BAD_REQUEST)
@ExceptionHandler(MethodArgumentNotValidException.class)
public Map<String, String> handleExceptions(MethodArgumentNotValidException notValidEceptions) {
//CREATE MAP FOR STORING ERRORS
Map<String, String> errors = new HashMap<>();
//ITERATE THROUGH ERRORS
List<ObjectError> objectErrors = notValidEceptions.getBindingResult().getAllErrors();
for(ObjectError objectError : objectErrors) {
//GET ERROR
FieldError fieldError = (FieldError) objectError;
String fieldName = fieldError.getField();
String errorMessage = fieldError.getDefaultMessage();
//STORE ERROR
errors.put(fieldName, errorMessage);
}
//RETURN ERRORS
return errors;
}
}
Application Structure
pom.xml
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
</dependencies>
