Spring Java - Parameter 0 of constructor

Question

I'm trying to write a simple CRUD program and I get this error. The program is based after codecademy project. Not sure why I doesn't work.

If I comment out the constructor the error disappears.I don't have anything in my properties.

Can someone give me a hand?

Description:

Parameter 0 of constructor in com.example.FitApp3.controller.FoodController required a bean of type 'com.example.FitApp3.repository.FoodRepository' that could not be found.


Action:

Consider defining a bean of type 'com.example.FitApp3.repository.FoodRepository' in your configuration.


Process finished with exit code 1

This is my code:

Entity/Food.java

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

@Entity
public class Food extends com.example.FitApp3.model.Entity {
    private String foodName;
    private int foodKcal;
    private int foodProtein;
    private int foodCarb;
    private int foodFat;

    public String getFoodName() {
        return foodName;
    }

    public void setFoodName(String foodName) {
        this.foodName = foodName;
    }

    public int getFoodKcal() {
        return foodKcal;
    }

    public void setFoodKcal(int foodKcal) {
        this.foodKcal = foodKcal;
    }

    public int getFoodProtein() {
        return foodProtein;
    }

    public void setFoodProtein(int foodProtein) {
        this.foodProtein = foodProtein;
    }

    public int getFoodCarb() {
        return foodCarb;
    }

    public void setFoodCarb(int foodCarb) {
        this.foodCarb = foodCarb;
    }

    public int getFoodFat() {
        return foodFat;
    }

    public void setFoodFat(int foodFat) {
        this.foodFat = foodFat;
    }
}

Repository/FoodRepository.java

public interface FoodRepository extends CrudRepository<Food, Integer> {}

Controller/FoodController.java

@RestController
public class FoodController {
    private FoodRepository foodRepository;

    public FoodController(FoodRepository foodRepository) {
        this.foodRepository = foodRepository;
    }
}

Mainclass

@SpringBootApplication
public class FitApp3Application {
    public static void main(String[] args) {
        SpringApplication.run(FitApp3Application.class, args);
        System.out.println("hello world");
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>FitApp3</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>FitApp3</name>
    <description>Demo project for Spring Boot</description>
    <properties>
          <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
      <dependency>
          <groupId>javax.persistence</groupId>
          <artifactId>javax.persistence-api</artifactId>
          <version>2.2</version>
      </dependency>
      <dependency>
          <groupId>org.springframework.data</groupId>
          <artifactId>spring-data-commons</artifactId>
          <version>2.5.1</version>
      </dependency>
  </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

Can you add @Repository annotation to FoodRepository interface.

@Repository
public interface FoodRepository extends CrudRepository<Food, Integer> {}

Answer 2

You need to replace spring-boot-starter-jdbc with spring-boot-starter-data-jpa as follows:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

You can have a look at the following links the difference between them, but basically, JPA helps you deal with your Database data by mapping it directly to Java objects:

• https://www.baeldung.com/jpa-vs-jdbc
• JPA or JDBC, how are they different?

Answer 3

I think you are just a little bit confused with spring-jdbc, spring-data and spring persistence interfaces abstraction, let me help. TL;DR solution is at the bottom:

In the constructor of FoodController you are declaring FoodRepository as a parameter, so spring have to find the bean of this time at runtime in order to create bean of FoodController. You have declared FoodRepository and extend it from CrudRepository. I guess, that you have done it with the assumption, that spring will create an implementation of FoodRepository at runtime (because it extends CrudRepository). But, unfortunately, it is not the spring-core module, that will create bean of FoodRepsitory, nor it is spring-jdbc. This interfaces are the part of spring-data project. So, for creation of the bean of the type FoodRepository is responsible current spring-data project in your classpath (I mean, it could be spring-data-jdbc, spring-data-jpa or whatever). This interfaces (CrudRepository, Repository e.t.c.) are common for all of the spring data projects, so they are shipped in spring-data-commons jar, this is why you have them available in classpath, because you have included spring-data-commons explicitly:

  <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-commons</artifactId>
      <version>2.5.1</version>
  </dependency>

Another thing is that this starter:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

does not do anything with spring-data project - it just brings spring-jdbc, Hikari connection pool, and some other spring-boot stuff. In other words, the problem is that you do not have any spring-data project in your classpath, thats why FoodRepository bean is not created.

Also note: @Entity does not make sense here, becuase you do not have any jpa persistence provider in classpath

Solution:

To solve the problem, I suggest you to

1. Remove spring-data-commons dependency from pom.xml
2. Include spring-boot-starter-data-jpa into your project (into pom.xml). It will bring the appropriate version of spring-data-commons dependency.

Hope it helped, have a nice day!

Answer 4

Add @Repository annotation to FoodRepository interface and also @Autowired annotation to the FoodRepository in FoodController.