How to map a Java class property that is an object to a single JPA table column?

Question

我有一个 Sprint Boot web 服务，它使用 JPA 到 map 到基础 Z9778840A06741CB30B5A2Z8 数据库。

其中一个域类具有一个复杂的属性 Java object，我不想与正常的映射/连接表保持一致。 Instead I want to map this Java object to a single column in the main table, and ideally store the data in a JSON format in a string column.

有什么建议么？

Answer 1

您可以使用 jpa 的AttributeConverter ：

@Converter
public class MyObjectConverter implements AttributeConverter<MyObject, String> {
 @Override
 public String convertToDatabaseColumn(MyObject myObject) {
    //convert myobject to json: for instance use ObjectMapper from Jackson
    if( myObject == null )
        return null;

    ObjectMapper mapper = new ObjectMapper();
    return mapper.writeValueAsString(myObject );
 }

 @Override
 public MyObject convertToEntityAttribute(String myObjectString) {
    // convert myObjectString back to object
    if( myObjectString== null )
        return null;

    ObjectMapper mapper = new ObjectMapper();
    return mapper.readValue(myObjectString, MyObject.class);
 }  
}

并在您的实体中使用它作为..

@Column
@Converter(converter = MyObjectConverter.class)
MyObject myObject;