org.springframework.web.util.NestedServletException: Request processing failed; nested exception is

[Dima Kh]

I am following Spring in Action 5 and have error:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: Error accessing field [private final java.lang.String org.server.models.Ingredient.id] by reflection for persistent property [org.server.models.Ingredient#id] : SLSA; nested exception is org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [private final java.lang.String org.server.models.Ingredient.id] by reflection for persistent property [org.server.models.Ingredient#id] : SLSA
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

That`s how my entity Ingredient looks:

@Data
@RequiredArgsConstructor
@NoArgsConstructor(access = AccessLevel.PRIVATE, force = true)
@Entity
@Table(name = "ingredient", schema = "public")
public class Ingredient {

    @Id
    @Column(columnDefinition = "String", name = "id")
    private final String id;
    private final String name;
    @Enumerated(EnumType.STRING)
    private final Type type;

    public static enum Type{
        WRAP, PROTEIN, VEGGIES, CHEESE, SAUCE
    }

}

And  my Taco entity:

@Data
@Entity
@Table(name = "taco", schema = "public")
public class Taco {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private Date createdAt;
    @NotNull
    @Size(min = 3, message="Name must be at least 3 characters long")
    private String name;
    @ManyToMany(targetEntity = Ingredient.class)
    @Size(min=1, message="You must choose at least 1 ingredient")
    private List<String> ingredients;

    @PrePersist
    void createdAt(){
        this.createdAt = new Date();
    }

}

In @Controller I am trying to save new Taco()  to Database but have the error above.
My Controller:

@Controller
@RequestMapping("/design")
@SessionAttributes("order")
public class DesignTacoController {

    private final IngredientRepository ingredientRepository;
    private final TacoRepository tacoRepository;

    @Autowired
    public DesignTacoController(IngredientRepository ingredientRepository, TacoRepository tacoRepository) {
        this.ingredientRepository = ingredientRepository;
        this.tacoRepository = tacoRepository;
    }

    @ModelAttribute(name = "order")
    public Order order(){
        return new Order();
    }

    @GetMapping
    public String showDesignForm(Model model){
        List<Ingredient> ingredients = new ArrayList<>();
        ingredientRepository.findAll().forEach(i -> ingredients.add(i));

        Type[] types = Ingredient.Type.values();
        for (Type type : types){
            model.addAttribute(type.toString().toLowerCase(),
                    filterByType(ingredients, type));
        }
        return "welcomePage";
    }

    private List<Ingredient> filterByType(List<Ingredient> ingredients, Type type) {
        return ingredients
                .stream()
                .filter(x -> x.getType().equals(type))
                .collect(Collectors.toList());
    }

    @ModelAttribute(name = "taco")
    public Taco taco(){
        return new Taco();
    }

    @PostMapping
    public String processDesign(@Valid Taco taco, Errors errors, @ModelAttribute Order order){
        if(errors.hasErrors()) {
            return "welcomePage";
        }
        Taco saved = tacoRepository.save(taco);
        order.addDesign(saved);
        return "redirect:/orders/current";
    }
}

Why am I getting this error and how can I fix it? Thanks for advance.

[Stephan van Hulst]

It's probably because your fields are final.

[Dima Kh]

Stephan van Hulst I've tried to delete final and I have gotten the same exception but without text:"private final"

[Stephan van Hulst]

Does it make a difference if you add setters and getters?

[Himai Minh]

Hi , Dima,
Have your install Lombok plugin to your IDE (Eclipse or IntelliJ)?
With Lombok, you don't need to define getter and setter methods.

[Dima Kh]

I have solved this error edited Taco class like:

private List<String> ingredients; to private List<Ingredient> ingredients;

write converter for it because thymeleaf returns String from form:

@Component
public class IngredientByIdConverter implements Converter<String, Ingredient>{

    private final IngredientRepository ingredientRepo;

    @Autowired
    public IngredientByIdConverter(IngredientRepository ingredientRepo) {
        this.ingredientRepo = ingredientRepo;
    }

    @Override
    public Ingredient convert(String id) {
        Optional<Ingredient> optionalIngredient = ingredientRepo.findById(id);
        return optionalIngredient.isPresent() ?
                optionalIngredient.get() : null;
    }

}

And added it to configuration class:

    @Autowired
    private IngredientRepository ingredientRepository;

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new IngredientByIdConverter(ingredientRepository));
    }

[Himai Minh]

Hi, Dima. I assume you are refering to ch 03 taco-jpa module of the book.
Can you try to update the pom.xml of taco-jpa and see if it works without changing any original code?
Please refer to the bold type of the following pom.xml.
Also, if you are using IntelliJ, make sure your project setting's compiler is set to JDK 11 if you are using it.

<?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
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>sia</groupId>
<artifactId>taco-cloud</artifactId>
<version>0.0.3-SNAPSHOT</version>
<packaging>jar</packaging>

<name>taco-cloud</name>
<description>Taco Cloud Example</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>
UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>
UTF-8</project.reporting.outputEncoding>
<java.version>11</java.version>
    </properties>

<dependencies>
<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>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<version>2.2.4.RELEASE</version>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
</dependency>

   <dependency>
     <groupId>org.seleniumhq.selenium</groupId>
     <artifactId>selenium-java</artifactId>
     <scope>test</scope>
   </dependency>

   <dependency>
     <groupId>org.seleniumhq.selenium</groupId>
     <artifactId>htmlunit-driver</artifactId>
     <scope>test</scope>
   </dependency>

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

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope>
</dependency>

<!-- tag::springDataJpa[] -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- end::springDataJpa[] -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.2</version>
</dependency>

<!-- Runtime, com.sun.xml.bind module -->
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>2.3.2</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.4.9.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.4.9.Final</version>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<version>3.2.4</version>
</dependency>
</dependencies>

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

</project>