I am very new to Spring boot and this is my first spring dummy project where I'm trying to learn to save an array of objects in mysql-db.
Actually, I am trying to use the saveAll method from the crudRepository in my controller. But it's giving me an error no instance(s) of type variable(s) S exist so that Iterable<S> conforms to List<User>
My JSON looks like this:
[
{
"first_name": "Jack",
"last_name": "Jill",
"email": "[email protected]",
"password": "passq3623"
},
{
"first_name": "John",
"last_name": "Doe",
"email": "[email protected]",
"password": "pass23"
}
]
This is my entity class
package com.example.testbatch.Entities;
import javax.persistence.*;
@Entity
@Table(name = "user")
public class UserEntity {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public int id;
public String first_name;
public String last_name;
public String email;
public String password;
}
Here is my User Model Class
package com.example.testbatch.Models;
public class User {
public int id;
public String firstName;
public String lastName;
public String email;
public String password;
}
Here is my repository
package com.example.testbatch.Repositories;
import com.example.testbatch.Entities.UserEntity;
import org.springframework.data.repository.CrudRepository;
import java.util.List;
public interface UserRepository extends CrudRepository<UserEntity, Integer> {
@Override
List<UserEntity> findAll();
}
and here is my rest controller
package com.example.testbatch.Controllers;
import com.example.testbatch.Entities.UserEntity;
import com.example.testbatch.Models.User;
import com.example.testbatch.Repositories.UserRepository;
import org.apache.poi.ss.formula.functions.T;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import javax.transaction.Transactional;
import java.util.ArrayList;
import java.util.List;
@RestController
@RequestMapping("/api/v1/user")
public class UserController {
@Autowired
UserRepository userRepository;
@PostMapping("/register")
public void saveUsers(@RequestBody UserEntity userEntity) {
List<User> persistedUser = userRepository.saveAll(List.of(userEntity));
}
}
Can anyone please help me? This is ery first time I am usig spring boot
CodePudding user response:
You have some problems about your code:
At first you have a DTO (User
class), so, you should use this DTO inside your controller in saveUsers
method and more importantly you pass an array of objects in your JSON, so you have to use a List
not an Object
as the parameter:
public void saveUsers(@RequestBody List<User> users) {...}
Another problem is you don't have any getters
and setters
inside you DTO (public class User
) and Entity (public class UserEntity
) classes and also you have to add a method inside your DTO class for mapping DTO to Entity:
public class User {
...
public static UserEntity dtoToEntity(User user){
UserEntity userEntity = new UserEntity();
userEntity.setEmail(user.getEmail());
userEntity.setPassword(user.getPassword());
userEntity.setFirst_name(user.getFirstName());
userEntity.setLast_name(user.getLastName());
return userEntity;
}
}
Also you must change your JSON properties to match your DTO's properties:
[
{
"firstName": "Jack",
"lastName": "Jill",
...
},
...
]
As the last one, change your controller saveUsers
method as (saveAll method return Iterable
not List
):
@PostMapping("/register")
public void saveUsers(@RequestBody List<User> users) {
List<UserEntity> userEntities = new ArrayList<>();
for (User user : users) {
userEntities.add(dtoToEntity(user));
}
Iterable<UserEntity> persistedUser = userRepository.saveAll(userEntities);
}
Notice: As a point remember that because you have auto-generated id inside your Entity, so you don't need id property for your DTO, obviously because it's auto-generated and you don't need to get it from input;
CodePudding user response:
The user_repo is returning a List of type UserEntity while in yout controller you are asking for a List of type User
There is not mapping between UserEntity and User.