Question

我正在尝试使用spring jpa在数据库上的两个不同表之间建立关系。但是，每次我尝试执行@OnetoMany或@ManytoOne时，都会收到标题中提到的错误。

学生：

    package EIC.com.example.Backend.Entity;
    import org.hibernate.annotations.Cascade;
    import javax.persistence.*;

    @Entity
    @Table(name = "etudiant")

    public class Student {
        @Id
        @Column(name="Apogee")
        private int id;
        @Column(name="Prenom")
        private String first_name;
        @Column(name="Nom")
        private String last_name;
        @Column(name="Classement")
        private int rank;
        @Column(name="Filiere")
        private String speciality;
        @ManyToOne
        @Column(name = "Offre")
        private Offer school; 
        /* GETTERS SETTERS CONSTRUCTORS */
    }

优惠：

    package EIC.com.example.Backend.Entity;
    import javax.persistence.*;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    @Entity
    public class Offer {
        @Id
        @Column(name = "ID_OFFRE")
        private int id;
        @Column(name = "Type")
        private int type; // 0 for DD 1 for MOBILITY
        @Column(name = "Etablissement")
        private String school;
        @Column(name = "Filiere_Concerne")
        private String target;
        @Column(name = "Nb_place")
        private int seats;
        @Column(name = "Delai")
        private Date limit;
        @OneToMany
        @JoinColumn(name = "Offre")
        private List<Student> students=new ArrayList<>();
        /* GETTERS SETTERS CONSTRUCTORS */
    }

依赖项：

http://maven.apache.org/xsd/maven-4.0.0.xsd“> 4.0.0 org.springframework.boot 弹簧启动启动器父母 2.1.2发布 EIC.com.example 后端 0.0.1-快照后端带有Spring Boot和Angular的EIC项目

<properties>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-cache</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>
    <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.data</groupId>
        <artifactId>spring-data-rest-hal-browser</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.session</groupId>
        <artifactId>spring-session-core</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.39</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

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

Answer 1

我认为您看到的错误与您发布的Bean的配置无关。引导程序正在为您创建此entityManager，但无法成功。

检查this post-这可能是关键。

Answer 2

U不能一次拥有@Column和@ManyToOne

使用@JoinColumn代替@Column。您的学生班级应该像这样：

@Entity
@Table(name = "etudiant")

    public class Student {
        @Id
        @Column(name="Apogee")
        private int id;
        @Column(name="Prenom")
        private String first_name;
        @Column(name="Nom")
        private String last_name;
        @Column(name="Classement")
        private int rank;
        @Column(name="Filiere")
        private String speciality;
        @ManyToOne
        @JoinColumn(name = "Offre")
        private Offer school; 
        /* GETTERS SETTERS CONSTRUCTORS */
    }

春季：在类路径资源

2 个答案: