B类中构造函数的参数0需要一个找不到A类类型的Bean

Question

Am making an API authentication feature with JWT in Spring boot rest , but am facing the following error :

Description :

Parameter 0 of constructor in com.icfer.huxy.icfer.controller.UserController required a bean of type 'com.icfer.huxy.icfer.service.ApplicationUserRepository' that could not be found.

Action :

Consider defining a bean of type 'com.icfer.huxy.icfer.service.ApplicationUserRepository' in your configuration.

Below is what I have implemented regarding ApplicationUserRepository , and UserController classes.

ApplicationUserRepository.java

import com.icfer.huxy.icfer.model.ApplicationUser;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Component;


public interface ApplicationUserRepository extends JpaRepository<ApplicationUser, Long> {
    ApplicationUser findByUsername(String username);
}

ApplicationUser.java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class ApplicationUser {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String username;
    private String password;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

UserController.java

import com.icfer.huxy.icfer.model.ApplicationUser;
import com.icfer.huxy.icfer.service.ApplicationUserRepository;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/users")
public class UserController {

    private ApplicationUserRepository applicationUserRepository;
    private BCryptPasswordEncoder bCryptPasswordEncoder;


    public UserController(ApplicationUserRepository applicationUserRepository,
                          BCryptPasswordEncoder bCryptPasswordEncoder) {
        this.applicationUserRepository = applicationUserRepository;
        this.bCryptPasswordEncoder = bCryptPasswordEncoder;
    }

    @PostMapping("/sign-up")
    public void signUp(@RequestBody ApplicationUser user) {
        user.setPassword(bCryptPasswordEncoder.encode(user.getPassword()));
        applicationUserRepository.save(user);
    }
}

My gradle file de is as below :

dependencies {
    implementation('org.springframework.boot:spring-boot-starter-data-jpa')
    implementation('org.springframework.boot:spring-boot-starter-security')
    implementation('org.springframework.boot:spring-boot-starter-web')
    compile("com.auth0:java-jwt:3.4.0")
    runtimeOnly('mysql:mysql-connector-java')
    testImplementation('org.springframework.boot:spring-boot-starter-test')
    testImplementation('org.springframework.security:spring-security-test')
}

Below is the link to my project: Github link

Answer 1

One more reason sharing an actual sample is helpful as none of the code you've shared provides the information that we need to help you.

On your @SpringBootApplication you have the following:

@SpringBootApplication
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class, WebMvcAutoConfiguration.class})
public class IcferApplication { ... }

Because you are excluding DataSourceAutoConfiguration , no DataSource is created. There is no DataSource so JPA does not kick in. JPA is not started so your JPA repository is not created.

You could have ran your app in debug mode (ie by adding a -Ddebug system property):

   JpaRepositoriesAutoConfiguration:
      Did not match:
         - @ConditionalOnBean (types: javax.sql.DataSource; SearchStrategy: all) did not find any beans of type javax.sql.DataSource (OnBeanCondition)
      Matched:
         - @ConditionalOnClass found required class 'org.springframework.data.jpa.repository.JpaRepository' (OnClassCondition)
         - @ConditionalOnProperty (spring.data.jpa.repositories.enabled=true) matched (OnPropertyCondition)

Also, please don't use EnableAutoConfiguration together with SpringBootApplication , there is an exclude attribute on the latter as well.

Once I removed the exclude on DataSourceAutoConfiguration that error went away.