Could not set field value by reflection

Question

I have a problem with a many to many relationship. The tables are: ingredient and nutional value. I created a table of relations between the 2 entities, in which there are the external keys of ingredient and nutrional value (which form the compound key) and some attributes.

Class JoinedNutrionalValueIngredient:

import lombok.Data;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import java.io.Serializable;

@Entity @Data
public class JoinedNutrionalValueIngredient implements Serializable {

    @EmbeddedId
    private NutrionalValueIngredientId id;

    @ManyToOne(fetch= FetchType.LAZY)
    @MapsId("ingredient_id")
    private Ingredient ingredient;

    @ManyToOne(fetch=FetchType.LAZY)
    @MapsId("nutrional_value_id")
    private NutrionalValue nutrionalValue;

    @NotNull
    String matrixUnit;

    @NotNull
    int value;

    @NotNull
    String valueType;
}

Class NutrionalValueIngredientId:

import javax.persistence.*;
import java.io.Serializable;
import java.util.Objects;

@Embeddable
@Getter
@Setter
public class NutrionalValueIngredientId implements Serializable{

    @Column(name = "ingredient_id")
    private Long ingredient_id;

    @Column(name = "nutrional_value_id")
    private Long nutrional_value_id;

    public NutrionalValueIngredientId() {
        
    }   
   
    public NutrionalValueIngredientId(Long ingredient, Long nutrionalValue){
        this.ingredient_id=ingredient;
        this.nutrional_value_id=nutrionalValue;
    }
    
    public boolean equals(Object o) {
        if (this == o) return true;
    
        if (o == null || getClass() != o.getClass())
            return false;
    
        NutrionalValueIngredientId that = (NutrionalValueIngredientId) o;
        return Objects.equals(ingredient_id, that.ingredient_id) &&
                    Objects.equals(nutrional_value_id, that.nutrional_value_id);
    }
    
    @Override
    public int hashCode() {
        return Objects.hash(ingredient_id, nutrional_value_id);
    }
}

When I try to insert a new field inside the relationship table I get this error:

{
  "timestamp": 1542653896247,
  "status": 500,
  "error": "Internal Server Error",
  "message": "Could not set field value [1] value by reflection : [class com.whateat.reciper.model.NutrionalValueIngredientId.ingredient_id] setter of com.whateat.reciper.model.NutrionalValueIngredientId.ingredient_id; nested exception is org.hibernate.PropertyAccessException: Could not set field value [1] value by reflection : [class com.whateat.reciper.model.NutrionalValueIngredientId.ingredient_id] setter of com.whateat.reciper.model.NutrionalValueIngredientId.ingredient_id",
  "path": "/v1/joinedNutrionalValueIngredients"
}

Edit: I added constructor and annotation @Getter and @Setter, but I have the same error.

class NutritionalValue:

@Data
@Entity
public class NutrionalValue implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotNull
    private String name;

    @NotNull
    private String unit;

    @NotNull
    private String source;

    @ManyToOne
    @NotNull
    @JoinColumn(name = "category_id")
    private NutrionalValueCategory category;

    @OneToMany(mappedBy = "nutrionalValue")
    private Set<JoinedNutrionalValueIngredient> joined = new HashSet<JoinedNutrionalValueIngredient>();

}

edit: after Debopam's answer, this error came out.

{
  "timestamp": 1542657216244,
  "status": 500,
  "error": "Internal Server Error",
  "message": "null id generated for:class com.whateat.reciper.model.JoinedNutrionalValueIngredient; nested exception is org.hibernate.id.IdentifierGenerationException: null id generated for:class com.whateat.reciper.model.JoinedNutrionalValueIngredient",
  "path": "/v1/joinedNutrionalValueIngredients"
}

Solution 1

Change the variable Names as below

Long ingredient_id to Long ingredientid nutrional_value_id to nutrionalvalueid

Example

  @Column(name = "ingredient_id")
  Long ingredient_id;

to

@Column(name = "ingredient_id")
Long ingredientid;

Then generate getter setter for all the fields. Hibernate is unable to set the fields because there is no public getter/setter.

Solution 2

 @Entity @Data
 public class JoinedNutrionalValueIngredient implements Serializable {
    
        @EmbeddedId
        private NutrionalValueIngredientId id = new NutrionalValueIngredientId();
    
    // ... rest of class  
 }

In the JoinedNutrionalValueIngredient class the compound id NutrionalValueIngredientId shall be instansiated.

Comments

[Francesco]

Thanks for the reply. I changed the names of the variables, now I received another error.

[Francesco]

Having used spring data rest the crud operations were generated automatically. the solution proposed to us, however, would oblige me to rewrite the post method. what I would like to do is insert this table directly from the rest call. @Roshini

[Mat]

This is what I had to do. I was populating my equivalent of "ingredient" and "nutrionalValue", and getting the "Could not set field..." exception when saving. Doing the above fixed the issue for me.