我有一个多对多关系的问题。
这些表是:
成分和营养值(value)。
我创建了两个实体之间的关系表,其中有成分和营养值(value)的外部键(形成复合键)和一些属性。
类(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;
}
类(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);
}
}
当我尝试在关系表中插入一个新字段时,我收到此错误:{
"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"
}
编辑:我添加了构造函数和注释@Getter
和 @Setter
,但我有同样的错误。类(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>();
}
编辑:在Debopam的回答之后,这个错误就出来了。
{
"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"
}
最佳答案
@Entity @Data
public class JoinedNutrionalValueIngredient implements Serializable {
@EmbeddedId
private NutrionalValueIngredientId id = new NutrionalValueIngredientId();
// ... rest of class
}
在 JoinedNutrionalValueIngredient
类化合物是NutrionalValueIngredientId
应实例化。
关于java - 无法通过反射设置字段值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53381067/