我刚刚开始学习春天。当我尝试在春季行动书中对塔可云应用程序进行编程时，我收到"没有为实体指定标识符"错误。在第 3 章中，我尝试使用 H2 数据库学习 JPA。
我的订单型号：
package com.example.tacocloud.models;
import lombok.Data;
import javax.persistence.*;
import javax.validation.constraints.NotBlank;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
@Data
@Entity
@Table(name = "Taco_Order")
public class Order implements Serializable {
...
@Id
@GeneratedValue(strategy= GenerationType.AUTO)
private Long id;
private Date placedAt;
@ManyToMany(targetEntity=Taco.class)
private List<Taco> tacos = new ArrayList<>();
public void addDesign(Taco design) {
this.tacos.add(design);
}
@PrePersist
void placedAt() {
this.placedAt = new Date();
}
}
而我的成分.class看起来像这样：
package com.example.tacocloud.models;
import lombok.AccessLevel;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.RequiredArgsConstructor;
import javax.persistence.Embeddable;
import javax.persistence.Entity;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Data
@RequiredArgsConstructor
@NoArgsConstructor(access= AccessLevel.PRIVATE, force=true)
@Entity // if I change it to Embedded I get unmapped ManyToMany error in my Ingredient class.
public class Ingredient {
private final String id;
private final String name;
private final Type type;
public static enum Type{
WRAP, PROTEIN, VEGGIES, CHEESE, SAUCE
}
}
还有我的炸玉米饼课：
package com.example.tacocloud.models;
import lombok.Data;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.util.Date;
import java.util.List;
@Data
@Entity
public class Taco {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private Date createdAt;
@NotNull
@Size(min=5, message="Name must be at least 5 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();
}
}
和我的SQL文件：
delete from Taco_Order_Tacos;
delete from Taco_Ingredients;
delete from Taco;
delete from Taco_Order;
delete from Ingredient;
insert into Ingredient (id, name, type)
values ('FLTO', 'Flour Tortilla', 'WRAP');
insert into Ingredient (id, name, type)
values ('COTO', 'Corn Tortilla', 'WRAP');
insert into Ingredient (id, name, type)
values ('GRBF', 'Ground Beef', 'PROTEIN');
insert into Ingredient (id, name, type)
values ('CARN', 'Carnitas', 'PROTEIN');
insert into Ingredient (id, name, type)
values ('TMTO', 'Diced Tomatoes', 'VEGGIES');
insert into Ingredient (id, name, type)
values ('LETC', 'Lettuce', 'VEGGIES');
insert into Ingredient (id, name, type)
values ('CHED', 'Cheddar', 'CHEESE');
insert into Ingredient (id, name, type)
values ('JACK', 'Monterrey Jack', 'CHEESE');
insert into Ingredient (id, name, type)
values ('SLSA', 'Salsa', 'SAUCE');
insert into Ingredient (id, name, type)
values ('SRCR', 'Sour Cream', 'SAUCE');
架构.sql：
create table if not exists Ingredient (
id varchar(4) not null,
name varchar(25) not null,
type varchar(10) not null
);
create table if not exists Taco (
id identity,
name varchar(50) not null,
createdAt timestamp not null
);
create table if not exists Taco_Ingredients (
taco bigint not null,
ingredient varchar(4) not null
);
alter table Taco_Ingredients
add foreign key (taco) references Taco(id);
alter table Taco_Ingredients
add foreign key (ingredient) references Ingredient(id);
create table if not exists Taco_Order (
id identity,
deliveryName varchar(50) not null,
deliveryStreet varchar(50) not null,
deliveryCity varchar(50) not null,
deliveryState varchar(2) not null,
deliveryZip varchar(10) not null,
ccNumber varchar(16) not null,
ccExpiration varchar(5) not null,
ccCVV varchar(3) not null,
placedAt timestamp not null
);
create table if not exists Taco_Order_Tacos (
tacoOrder bigint not null,
taco bigint not null
);
alter table Taco_Order_Tacos
add foreign key (tacoOrder) references Taco_Order(id);
alter table Taco_Order_Tacos
add foreign key (taco) references Taco(id);
顺便说一句，我的应用程序属性：
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driver-class-name = org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
谢谢。
你的类Ingredient没有@Id字段，而且它是一个不可变对象的类，不适合序列化类 - 你必须像其他所有类一样有默认构造函数。删除@NoArgsConstructor(access= AccessLevel.PRIVATE, force=true)这很奇怪，可能会混淆您的框架