Spring-Data-Jpa 存储库 - 实体列名称上的下划线 [英] Spring-Data-Jpa Repository - Underscore on Entity Column Name

问题描述

我在 spring webmvc 项目中使用 spring-data-jpa.我在使用 查询创建 在我的一个实体的存储库上.您可以在下面看到我的实体、我的存储库和异常.

I am using spring-data-jpa on a spring webmvc project. I am facing an issue using query creation on a Repository of one of my Entities. Below you can see my Entity, my Repository and the Exception.

我的实体:

@Entity
@Table(schema = "mainschema")
@XmlRootElement
public class Municipalperson implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(nullable = false)
    private Integer id;

    @Basic(optional = false)
    @Column(name = "municipal_id", nullable = false)
    private Integer municipal_id;

    @Basic(optional = false)
    @Column(nullable = false, length = 60)
    private String firstname;

    public Municipalperson(Integer id, Integer municipal_id, String firstname) {
        this.id = id;
        this.municipal_id = municipal_id;
        this.firstname = firstname;
    }


    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getMunicipal_id() {
        return municipal_id;
    }

    public void setMunicipal_id(Integer municipal_id) {
        this.municipal_id = municipal_id;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }
}

我的存储库:

@Repository
public interface MunicipalpersonRepository extends JpaRepository<Municipalperson, Integer> {

    List<Municipalperson> findByMunicipal_idOrderByLastnameDesc(int municipal_id);
}

和例外，

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'municipalpersonRepository': Invocation of init method failed; nested exception is org.springframework.data.mapping.PropertyReferenceException: No property municipal found for type Municipalperson!  

我尝试将 municipal_id 设置为 int，然后设置为 Integer 并且对于我的存储库中的参数 municipal_id 也是如此，但没有任何效果.此外，我将 Repository 重命名为 findByMunicipalidOrderByLastnameDesc 和 findByMunicipalIdOrderByLastnameDesc 但它也不起作用.

I tried to set municipal_id as int, then as Integer and the same for the parameter municipal_id on my Repository, but none worked. Also, I renamed the Repository to findByMunicipalidOrderByLastnameDesc and findByMunicipalIdOrderByLastnameDesc but it didn't work either.

最后，我将municipal_idmunicipal_id 重命名为municipalId(删除了下划线)并重命名了getter/setter 和Repository(findByMunicipalIdOrderByLastnameDesc) 并且问题已解决.

Finally I renamed the municipal_id to municipalId (underscore removed) and also renamed getters/setters and the Repository (findByMunicipalIdOrderByLastnameDesc) and the issue was resolved.

我的问题是为什么会这样?

My question is why this is happening?

推荐答案

下划线 _ 是 Spring Data 查询派生中的保留字符(请参阅 参考文档 以了解详细信息)以可能允许手动属性路径描述.所以你有两个选择:

The underscore _ is a reserved character in Spring Data query derivation (see the reference docs for details) to potentially allow manual property path description. So there are two options you have:

1. 坚持使用 camel-case 作为成员变量名称的 Java 命名约定，一切都会按预期工作.
2. 使用额外的下划线对 _ 进行转义，即将您的查询方法重命名为 findByMunicipal__idOrderByLastnameDesc(…).

1. Stick to the Java naming conventions of using camel-case for member variable names and everything will work as expected.
2. Escape the _ by using an additional underscore, i.e. rename your query method to findByMunicipal__idOrderByLastnameDesc(…).

我推荐前者，因为您不会疏远其他 Java 开发人员:)

I'd recommend the former as you're not going to alienate fellow Java developers :).

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