获取：通过字段“ userRepository”表达的不满意的依赖性

Question

Unsatisfied dependency expressed through field 'userRepository'

Can anyone tell me what I'm missing or need to add? Thanks a lot in advance!

Here's a picture of my project structure.

User.java

package org.codigo.entites;

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

@Entity
public class User {

@Id
@GeneratedValue
private Long id;
private String fname;
private String lname;
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getFname() {
    return fname;
}
public void setFname(String fname) {
    this.fname = fname;
}
public String getLname() {
    return lname;
}
public void setLname(String lname) {
    this.lname = lname;
}
public User(String fname, String lname) {
    this.fname = fname;
    this.lname = lname;
}
public User() {
}
@Override
public String toString() {
    return "User [id=" + id + ", fname=" + fname + ", lname=" + lname + "]";
}
}

UserRepository.java

package org.codigo.repositories;

import org.codigo.entites.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {

}

Answer 1

Your UserRepository is interface, you cannot create bean for interface

public interface UserRepository extends JpaRepository<User, Long>

Declare UserRepository as class with method implementations and annotate with @Repository annotation, if JpaRepository is interface then you should use implements keyword

@Repository
public class UserRepository extends JpaRepository<User, Long>

Answer 2

Whenever Spring says Unsatisfied dependency , it does not know how to obtain an instance of the desired type.

To let Spring know and even implement your repository (just the interface), you should

add @EnableJpaRepositories to MyAppApplication :

@SpringBootApplication
@EnableJpaRepositories(basePackage = "org.codigo.repositories")
public class MyAppApplication implements CommandLineRunner { ... }

This seems like magic at first - behind the scenes Spring will instantiate a dynamic proxy for your repository which intercepts all method calls and finds out what to do, based on the called method's name, its parameters and return type.

Reference:

• Spring Boot / Data Access / Use Spring Data Repositories
• Spring Data JPA - Reference Documentation / JPA Repositories