如何使用 Springboot 和 Hibernate 在 DTO 和 Aggentity 类中映射 Postgres JSON 数据类型

Question

我有一个 ResponseDto 类，如下所示：

public static class HealthGoalsHighlight {

    @ApiModelProperty(value = "Total number of eligible users")
    private Long totalEligibleUsers;
    @ApiModelProperty(value = "Total number of registered users")
    private Long totalRegisteredUsers;
    @ApiModelProperty(value = "Total number of users with atleast one goal count")
    private Long totalUsersWithGoal;
    @ApiModelProperty(value = "Top goal name selected by user")
    private String topGoal;
    @ApiModelProperty(value = "Bottom goal name selected by user")
    private String bottomGoal;
  }

此 DTO 是根据下表结构制作的：

health_goals
(
  uid BIGSERIAL NOT NULL CONSTRAINT health_goals_pkey primary key,
  employer_key bigint not null,
  total_eligible_users bigint not null,
  total_registered_users bigint not null,
  total_users_with_goal bigint not null,
  top_goal_name varchar(255),
  bottom_goal_name varchar(255),
  created_ts TIMESTAMP NOT NULL DEFAULT NOW(),
  updated_ts TIMESTAMP NOT NULL DEFAULT NOW(),
  created_by varchar(255),
  updated_by varchar(255)
);

现在表结构已更改为：

health_goals
(
  uid BIGSERIAL NOT NULL CONSTRAINT health_goals_pkey primary key,
  employer_key bigint not null,
  health_goals_metric_value json null,
  created_ts TIMESTAMP NOT NULL DEFAULT NOW(),
  updated_ts TIMESTAMP NOT NULL DEFAULT NOW(),
  created_by varchar(255),
  updated_by varchar(255)
);

现在基本上所有这些列，如total_eligible_users、total_registered_users、total_users_with_goal、top_goal_name、bottom_goal_name 将被合并为单个列health_goals_metric_value 作为 JSON 数据类型。

如何为 JSON 数据类型列编写响应 DTO。另外，我的 AggMapper 类中需要进行哪些更改。

Answer 1

一种方法是使用转换器功能。您可以使用转换器函数来获取相同格式的值。

在您的列定义中更改您的orm.xml 如下所示

<basic name="healthGoalsMetricValue">
                <column name="health_goals_metric_value" nullable="true"/>
                <convert converter="path.to.your.HealthGoalsMetricValueConverter"/>
            </basic>

或者如果你有java文件

代理将有以下条目

  @Convert(converter = HealthGoalsMetricValueConverter.class)
    private HealthGoalsHighlight healthGoalsHighlight ;

你的班级 HealthGoalsMetricValue 看起来像

////////////////在cmets之后编辑转换器类

       import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;
import java.io.IOException;

@Converter
public class HealthGoalsMetricValueConverter implements AttributeConverter<HealthGoalsMetricValue, String> {

private final ObjectMapper mapper = new ObjectMapper();

//And then override like that
@Override
        public String convertToDatabaseColumn(HealthGoalsHighlight healthGoalsMetricValue) {

            try {                
                json = mapper.writeValueAsString(healthGoalsMetricValue);
            } catch (JsonProcessingException exception) {
                throw new JsonProcessingException("Error occurred while object serialization", exception);
            }
            return json;
    }

 //And then override again
@Override
public HealthGoalsMetricValue  convertToEntityAttribute(String healthGoalsMetricValuestr ) {
    HealthGoalsMetricValue  healthGoalsMetricValue  = null;
    try {
        if (healthGoalsMetricValue != null) {
            healthGoalsMetricValue = mapper.readValue(healthGoalsMetricValuestr, HealthGoalsMetricValue.class);
        }
    } catch (Exception exception) {
        throw new Exception("Error occurred while object Deserialization", exception);
    }
    return healthGoalsMetricValue;
}

这一切都将为您完成工作。

Answer 2

如果您可以添加其他库，请查看 https://github.com/vladmihalcea/hibernate-types 项目，这非常容易。

有了这个库，你最终会得到像这样简单的代码

@Entity
@Table(name = "health_goals")
@TypeDefs({
    @TypeDef(name = "json", typeClass = JsonStringType.class),
    @TypeDef(name = "jsonb", typeClass = JsonBinaryType.class)
})
public class HealthGoal {
    // all other columns
    @Type(type = "json")
    private HealthGoalsHighlight healthGoalsHighlight;

    // getters setters

}

如果使用maven添加依赖

<dependency>
  <groupId>com.vladmihalcea</groupId>
  <artifactId>hibernate-types-52</artifactId>
  <version>2.9.10</version> // or newer version
</dependency>