How can solve JSON column in H2

问题:

I use in application MySQL 5.7 and I have JSON columns. When I try running my integration tests don't work because the H2 database can't create the table. This is the error:

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:

This is the entity class.

@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;
    }
}

And the subclass:

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;
    }

}

And this converter for insert in database:

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;

    }
}

回答1:

H2 does not have a JSON data type.

JSON essentially is just a potentially very long string, so you can use CLOB which is available on most databases.

You need a JSON type at row level only if you need an SQL function that operates on them, and then only if the database insists that its JSON functions operate on a JSON type instead of on a CLOB.

回答2:

I just came across this problem working with the JSONB column type - the binary version of the JSON type, which doesn't map to TEXT.

For future reference, you can define a custom type in H2 using CREATE DOMAIN, as follows:

CREATE domain IF NOT EXISTS jsonb AS other;

This seemed to work for me, and allowed me to successfully test my code against the entity.

Source: https://objectpartners.com/2015/05/26/grails-postgresql-9-4-and-jsonb/

回答3:

I have solved the problem using TEXT type in H2. One must create a separate database script to create schema in H2 for tests and replace the JSON type by TEXT.

It is still a problem since if you use Json function in queries, you will not be able to test those while with H2.

回答4:

H2 does not have the JSON data type.

In MySQL the JSON type is just an alias for the LONGTEXT data type so the actual data type for the column will be LONGTEXT.