获取JPA中的列名 [英] Get column name in jpa

问题描述

我有一个查询工厂，该工厂将列名作为属性来搜索该列.现在，我将列名作为字符串传递，因此它是硬编码的.如果该列的名称在实体的注释中发生更改，则该隐藏的依赖项"将中断.

I have a query factory that takes a column name as an attribute in order to search for that column. Right now I'm passing the name of the column as a string, so it's kind of hardcoded. If the name of the column changes in the entity's annotation, that "hidden dependency" breaks up.

jpa中是否有一种方法可以检索列的真实名称并在编译时可用，所以我可以在查询中使用它?

Is there a way in jpa to retrieve the real name of the column and have it available at compile time, so I can use it in queries?

推荐答案

当然，注解总是存在反思.假设您具有典型的JPA列定义:

Of course, there is always reflection on annotations. Suppose you have typical JPA column definition:

    @Basic(optional = true)
    @Column(name = "MY_COLUMN_NAME_DESC", nullable = true, length = 255)
    public String getDesc() {
        return desc;
    }

然后检查getter方法将产生列名值(示例取自此处):

Then having getter method inspected yields column name value (example adopted from here):

Method method = ... //obtain entity object
Annotation[] annotations = method.getDeclaredAnnotations();

for(Annotation annotation : annotations){
    if(annotation instanceof Column){
        Column myAnnotation = (Column) annotation;
        System.out.println("name: " + myAnnotation.name());
        System.out.println("value: " + myAnnotation.value());
    }
}

该示例假定方法属性访问 JPA实体，但是没有什么可以阻止您通过对字段应用反射将其应用于字段级别.

The example assumes method property access in JPA entity but nothing prevents you to adopt it to field level by applying reflection to a field.

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