Spring-Data-Jpa存储库 - 实体列名称的下划线 [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。我正在使用查询创建在我的一个实体的存储库中。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!  

我试图将mynicipal_id设置为int，然后设置为Integer，并将参数'municipal_id'设置为相同我的存储库，但他们都没有工作。此外，我将存储库重命名为'findByMunicipalidOrderByLastnameDesc'和'findByMunicipalIdOrderByLastnameDesc'，但它既不起作用。

I tried to set mynicipal_id as int, then as Integer and the same for the parameter 'municipal_id' on my Repository, but they all didn't worked. Also, i rename the Repository to 'findByMunicipalidOrderByLastnameDesc' and 'findByMunicipalIdOrderByLastnameDesc' but it didn't worked neither.

最后我重命名将city_id更改为municipalId（删除了下划线），并重命名getter / setter和Repository（findByMunicipalIdOrderByLastnameDesc）和 问题解决了 。

Finally i renamed the municipal_id to municipalId (underscore removed) and also rename getters/setters and the Repository (findByMunicipalIdOrderByLastnameDesc) and the issue solved.

我的问题是为什么会发生这种情况？

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（参见参考文档以获取详细信息）以潜在地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 用于成员变量名称，一切都将按预期工作。


2. 转义 _ 使用额外的下划线，即将查询方法重命名为 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，因为你不会疏远其他Java开发人员:)。

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

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