Question

我没有找到使用JPA（EclipseLink）从PostgreSQL映射JSON和JSONB数据类型的方法。是否有人使用这种数据类型与JPA，并可以给我一些工作示例？

Answer 1

所有答案都帮助我达到了为JPA做好准备的最终解决方案，而不是EclipseLink或Hibernate。

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import javax.json.Json;
import javax.json.JsonObject;
import javax.persistence.Converter;
import org.postgresql.util.PGobject;

@Converter(autoApply = true)
public class JsonConverter implements javax.persistence.AttributeConverter<JsonObject, Object> {

  private static final long serialVersionUID = 1L;
  private static ObjectMapper mapper = new ObjectMapper();

  @Override
  public Object convertToDatabaseColumn(JsonObject objectValue) {
    try {
      PGobject out = new PGobject();
      out.setType("json");
      out.setValue(objectValue.toString());
      return out;
    } catch (Exception e) {
      throw new IllegalArgumentException("Unable to serialize to json field ", e);
    }
  }

  @Override
  public JsonObject convertToEntityAttribute(Object dataValue) {
    try {
      if (dataValue instanceof PGobject && ((PGobject) dataValue).getType().equals("json")) {
        return mapper.reader(new TypeReference<JsonObject>() {
        }).readValue(((PGobject) dataValue).getValue());
      }
      return Json.createObjectBuilder().build();
    } catch (IOException e) {
      throw new IllegalArgumentException("Unable to deserialize to json field ", e);
    }
  }
}

Answer 2

编辑：我现在看到这几乎是Hibernate依赖的。但也许你可以找到类似于EclipseLink ..

的东西

我只是添加我所拥有的答案，它来自另一个SO答案，但无论如何......这会将jsonb映射到Google JsonObject的{{1}}，但你可以如果需要，将其更改为其他内容。要更改为其他内容，请更改gson，nullSafeGet和nullSafeSet方法。

deepCopy

要使用此功能，请执行以下操作：

public class JsonbType implements UserType {

    @Override
    public int[] sqlTypes() {
        return new int[] { Types.JAVA_OBJECT };
    }

    @Override
    public Class<JsonObject> returnedClass() {
        return JsonObject.class;
    }

    @Override
    public boolean equals(final Object x, final Object y) {
        if (x == y) {
            return true;
        }
        if (x == null || y == null) {
            return false;
        }
        return x.equals(y);
    }

    @Override
    public int hashCode(final Object x) {
        if (x == null) {
            return 0;
        }

        return x.hashCode();
    }

    @Nullable
    @Override
    public Object nullSafeGet(final ResultSet rs,
                              final String[] names,
                              final SessionImplementor session,
                              final Object owner) throws SQLException {
        final String json = rs.getString(names[0]);
        if (json == null) {
            return null;
        }

        final JsonParser jsonParser = new JsonParser();
        return jsonParser.parse(json).getAsJsonObject();
    }

    @Override
    public void nullSafeSet(final PreparedStatement st,
                            final Object value,
                            final int index,
                            final SessionImplementor session) throws SQLException {
        if (value == null) {
            st.setNull(index, Types.OTHER);
            return;
        }

        st.setObject(index, value.toString(), Types.OTHER);
    }

    @Nullable
    @Override
    public Object deepCopy(@Nullable final Object value) {
        if (value == null) {
            return null;
        }
        final JsonParser jsonParser = new JsonParser();
        return jsonParser.parse(value.toString()).getAsJsonObject();
    }

    @Override
    public boolean isMutable() {
        return true;
    }

    @Override
    public Serializable disassemble(final Object value) {
        final Object deepCopy = deepCopy(value);

        if (!(deepCopy instanceof Serializable)) {
            throw new SerializationException(
                    String.format("deepCopy of %s is not serializable", value), null);
        }

        return (Serializable) deepCopy;
    }

    @Nullable
    @Override
    public Object assemble(final Serializable cached, final Object owner) {
        return deepCopy(cached);
    }

    @Nullable
    @Override
    public Object replace(final Object original, final Object target, final Object owner) {
        return deepCopy(original);
    }
}

此外，您需要设置方言以表明public class SomeEntity { @Column(name = "jsonobject") @Type(type = "com.myapp.JsonbType") private JsonObject jsonObject; = JAVA_OBJECT：

jsonb

Answer 3

我认为我发现了一个类似于Hibernate的EclipseLink用户类型。

http://www.eclipse.org/eclipselink/documentation/2.6/jpa/extensions/annotations_ref.htm#CHDEHJEB

您必须创建一个实现org.eclipse.persistence.mappings.converters.Converter的类并为您进行转换，然后在您使用该类型的每个字段上使用@Convert注释。

如何在JPA中使用Postgres JSONB数据类型？

3 个答案: