考虑在配置中定义类型为'com.ensat.services.ProductService'的bean

Question

I have

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplication
@ComponentScan(basePackages = {"hello","com.ensat.controllers"})
@EntityScan("com.ensat.entities")
public class Application extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }

}

ProductController.java

package com.ensat.controllers;

import com.ensat.entities.Product;
import com.ensat.services.ProductService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 * Product controller.
 */
@Controller
public class ProductController {

    private ProductService productService;

    @Autowired
    public void setProductService(ProductService productService) {
        this.productService = productService;
    }

    /**
     * List all products.
     *
     * @param model
     * @return
     */
    @RequestMapping(value = "/products", method = RequestMethod.GET)
    public String list(Model model) {
        model.addAttribute("products", productService.listAllProducts());
        System.out.println("Returning rpoducts:");
        return "products";
    }

    /**
     * View a specific product by its id.
     *
     * @param id
     * @param model
     * @return
     */
    @RequestMapping("product/{id}")
    public String showProduct(@PathVariable Integer id, Model model) {
        model.addAttribute("product", productService.getProductById(id));
        return "productshow";
    }

    // Afficher le formulaire de modification du Product
    @RequestMapping("product/edit/{id}")
    public String edit(@PathVariable Integer id, Model model) {
        model.addAttribute("product", productService.getProductById(id));
        return "productform";
    }

    /**
     * New product.
     *
     * @param model
     * @return
     */
    @RequestMapping("product/new")
    public String newProduct(Model model) {
        model.addAttribute("product", new Product());
        return "productform";
    }

    /**
     * Save product to database.
     *
     * @param product
     * @return
     */
    @RequestMapping(value = "product", method = RequestMethod.POST)
    public String saveProduct(Product product) {
        productService.saveProduct(product);
        return "redirect:/product/" + product.getId();
    }

    /**
     * Delete product by its id.
     *
     * @param id
     * @return
     */
    @RequestMapping("product/delete/{id}")
    public String delete(@PathVariable Integer id) {
        productService.deleteProduct(id);
        return "redirect:/products";
    }

}

ProductService.java

package com.ensat.services;

import com.ensat.entities.Product;

public interface ProductService {

    Iterable<Product> listAllProducts();

    Product getProductById(Integer id);

    Product saveProduct(Product product);

    void deleteProduct(Integer id);

}

ProductServiceImpl.java

package com.ensat.services;

import com.ensat.entities.Product;
import com.ensat.repositories.ProductRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * Product service implement.
 */
@Service
public class ProductServiceImpl implements ProductService {

    private ProductRepository productRepository;

    @Autowired
    public void setProductRepository(ProductRepository productRepository) {
        this.productRepository = productRepository;
    }

    @Override
    public Iterable<Product> listAllProducts() {
        return productRepository.findAll();
    }

    @Override
    public Product getProductById(Integer id) {
        return productRepository.findOne(id);
    }

    @Override
    public Product saveProduct(Product product) {
        return productRepository.save(product);
    }

    @Override
    public void deleteProduct(Integer id) {
        productRepository.delete(id);
    }

}

This is my error:

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method setProductService in com.ensat.controllers.ProductController required a bean of type 'com.ensat.services.ProductService' that could not be found.


Action:

Consider defining a bean of type 'com.ensat.services.ProductService' in your configuration.

I have full log: https://gist.github.com/donhuvy/b918e20eeeb7cbe3c4be4167d066f7fd

This is my full source code https://github.com/donhuvy/accounting/commit/319bf6bc47997ff996308c890eba81a6fa7f1a93

How to fix error?

Answer 1

The bean is not created by Spring since componentScan attribute misses the package where ProductServiceImpl is located.

Besides, @EnableJpaRepositories is missing. So, Spring cannot wire your repository.

@SpringBootApplication
@ComponentScan(basePackages = {"hello","com.ensat.controllers"})
@EntityScan("com.ensat.entities")

should be replaced by :

@SpringBootApplication
@ComponentScan(basePackages = {"hello","com.ensat.controllers", "com.ensat.services";
})
@EntityScan("com.ensat.entities")
@EnableJpaRepositories("com.ensat.repositories")

---

It will solve your problem but this way of doing defeats the convention over configuration advantage of Spring and Spring Boot.

If the Application bean class was located in a parent package which all other bean classes belongs to or to a sub-package of it, you would not need any longer to specify these two annotations :

@ComponentScan(basePackages = {"hello","com.ensat.controllers"})
@EntityScan("com.ensat.entities")

in the @SpringBootApplication class.

For example, moving Application in the com.ensat package and move all your beans in this package or in a child of it will both solve your configuration issues and alleviate your configuration.

package com.ensat;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application extends SpringBootServletInitializer {
    ...
}

Why ?

Because the @SpringBootApplication includes already them (and more) :

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
        @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
        @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {

But that uses the package of the current class as basePackage value to discover beans/entities/repositories, etc...

The documentation refers this point.

Here :

Many Spring Boot developers always have their main class annotated with @Configuration, @EnableAutoConfiguration and @ComponentScan. Since these annotations are so frequently used together (especially if you follow the best practices above), Spring Boot provides a convenient @SpringBootApplication alternative.

The @SpringBootApplication annotation is equivalent to using @Configuration, @EnableAutoConfiguration and @ComponentScan with their default attributes

Here it discusses about entities discovery provided by @EnableAutoConfiguration 77.3 Use Spring Data repositories point :

Spring Boot tries to guess the location of your @Repository definitions, based on the @EnableAutoConfiguration it finds. To get more control, use the @EnableJpaRepositories annotation (from Spring Data JPA).

Answer 2

I was experiencing this very error, and it took me a whole afternoon to figure it out. I have checked every stackoverflow post, spring.io docs, github issue related to this issue, and none of the answers could solve what was wrong.

In summary, I have tried:

1. Restructuring and renaming my packages and classes
2. Defining alternate classes for configuration
3. Deleting or remaking erroneous classes
4. Annotating my classes as thoroughly as possible
5. Defining classes altogether
6. Creating multiple code implementations to @Autowire my repositories
7. Banging my head on the wall in desperation -- okay, I might have overstepped on this a bit

Given I had two repositories, none of them was being recognized by or @EntityScan annotations. So in summary, I could not instantiate or perform any actions with them.

What did the trick for me, and what i'd suggest you do if you have exhausted your attempts is

1. . The error might not be related to your code (as it wasn't on mine).
2. If your dependencies are correct, then create a new Maven project with your revised pom.xml .
3. Update your Maven dependencies . It might be worth mentioning that I have done so through my IDE, which is the Eclipse + Spring Tool Suite (I don't believe the Spring Tool Suite did much of a difference in updating) 4. Structure your packages so that they follow the best practices (there's a nice article about this here .)
4. Then, carefully, migrate your files back. Start with the beans, execute your program, check for errors; then repositories, execute, test; then any startup scripts; then controllers etc. Take your time and make sure everything works.

Sometimes it can be very painful to debug these applications. I have had my share. I hope it helps!