如何解决H2中的JSON列

Question

我在应用程序MySQL 5.7中使用，并且具有JSON列。当我尝试运行集成测试时，由于H2数据库无法创建表，因此无法进行测试。这是错误：

2016-09-21 16:35:29.729 ERROR 10981 --- [           main] org.hibernate.tool.hbm2ddl.SchemaExport  : HHH000389: Unsuccessful: create table payment_transaction (id bigint generated by default as identity, creation_date timestamp not null, payload json, period integer, public_id varchar(255) not null, state varchar(255) not null, subscription_id_zuora varchar(255), type varchar(255) not null, user_id bigint not null, primary key (id))
2016-09-21 16:35:29.730 ERROR 10981 --- [           main] org.hibernate.tool.hbm2ddl.SchemaExport  : Unknown data type: "JSON"; SQL statement:

这是实体类。

@Table(name = "payment_transaction")
public class PaymentTransaction extends DomainObject implements Serializable {

    @Convert(converter = JpaPayloadConverter.class)
    @Column(name = "payload", insertable = true, updatable = true, nullable = true, columnDefinition = "json")
    private Payload payload;

    public Payload getPayload() {
        return payload;
    }

    public void setPayload(Payload payload) {
        this.payload = payload;
    }
}

和子类：

public class Payload implements Serializable {

    private Long userId;
    private SubscriptionType type;
    private String paymentId;
    private List<String> ratePlanId;
    private Integer period;

    public Long getUserId() {
        return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public SubscriptionType getType() {
        return type;
    }

    public void setType(SubscriptionType type) {
        this.type = type;
    }

    public String getPaymentId() {
        return paymentId;
    }

    public void setPaymentId(String paymentId) {
        this.paymentId = paymentId;
    }

    public List<String> getRatePlanId() {
        return ratePlanId;
    }

    public void setRatePlanId(List<String> ratePlanId) {
        this.ratePlanId = ratePlanId;
    }

    public Integer getPeriod() {
        return period;
    }

    public void setPeriod(Integer period) {
        this.period = period;
    }

}

并将此转换器插入数据库：

public class JpaPayloadConverter implements AttributeConverter<Payload, String> {

    // ObjectMapper is thread safe
    private final static ObjectMapper objectMapper = new ObjectMapper();

    private Logger log = LoggerFactory.getLogger(getClass());

    @Override
    public String convertToDatabaseColumn(Payload attribute) {
        String jsonString = "";
        try {
            log.debug("Start convertToDatabaseColumn");

            // convert list of POJO to json
            jsonString = objectMapper.writeValueAsString(attribute);
            log.debug("convertToDatabaseColumn" + jsonString);

        } catch (JsonProcessingException ex) {
            log.error(ex.getMessage());
        }
        return jsonString;
    }

    @Override
    public Payload convertToEntityAttribute(String dbData) {

        Payload payload = new Payload();
        try {
            log.debug("Start convertToEntityAttribute");

            // convert json to list of POJO
            payload = objectMapper.readValue(dbData, Payload.class);
            log.debug("JsonDocumentsConverter.convertToDatabaseColumn" + payload);

        } catch (IOException ex) {
            log.error(ex.getMessage());
        }
        return payload;

    }
}

Answer 1

提出问题后，H2添加了JSON支持，版本为1.4.200（2019-10-14）。

但是，您很少需要在数据库中使用JSON数据类型。JSON本质上只是一个可能很长的字符串，因此您可以使用大多数数据库都可用的CLOB。

如果需要对它们进行操作的SQL函数，并且仅在数据库坚持认为其JSON函数对JSON类型而不是对CLOB进行操作时，才需要JSON数据类型。但是，此类功能往往依赖于数据库。