如何在 MyBatis 中使用 UUID 类型处理程序和 @Many 注释？

我正在使用 mybatis-spring-boot-starter 2.1.0 版本。我需要处理 UUID 类型来获取嵌套集合。

 @Select("SELECT id, name FROM t_service s")
    @Results(value = {
            @Result(column = "id", property = "id", jdbcType = JdbcType.OTHER, typeHandler = UuidTypeHandler.class),
            @Result(column = "name", property = "name"),
            @Result(property = "rates", column = "id", javaType = List.class, many = @Many(select = "getAllRates"))
    })
    List<Service> findAll();

 @Select("SELECT date_from, date_to, currency FROM t_rate where t_rate.service_id = #{serviceId, javaType=java.util.UUID, jdbcType=OTHER, typeHandler=my.package.UuidTypeHandler}")
    @Results(value = {
            @Result(property = "dateFrom", column = "date_from"),
            @Result(property = "dateTo", column = "date_to"),
            @Result(property = "currency", column = "currency")
 })
    List<Rate> getAllRates(@Param("serviceId") UUID serviceId);

Uuid 类型处理程序：

@MappedJdbcTypes(JdbcType.OTHER)
@MappedTypes(UUID.class)
public class UuidTypeHandler extends BaseTypeHandler<UUID> {
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, UUID parameter, JdbcType jdbcType) throws SQLException {
        ps.setObject(i, parameter, jdbcType.TYPE_CODE);
    }

    @Override
    public UUID getNullableResult(ResultSet rs, String columnName) throws SQLException {
        return rs.getObject(columnName, UUID.class);
    }

    @Override
    public UUID getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return rs.getObject(columnIndex, UUID.class);
    }

    @Override
    public UUID getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return cs.getObject(columnIndex, UUID.class);
    }
}

但我得到以下异常：

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'serviceId' in 'class java.util.UUID'

在其他情况下（直接调用方法时）Uuid TypeHandler 工作正常，我没有任何问题

PostgreSQL 的解决方法：

 @Select("SELECT date_from, date_to, currency FROM t_rate where t_rate.service_id = #{serviceId}::uuid")
    @Results(value = {
            @Result(property = "dateFrom", column = "date_from"),
            @Result(property = "dateTo", column = "date_to"),
            @Result(property = "currency", column = "currency")
 })
    List<Rate> getAllRates(@Param("serviceId") String serviceId);

为了使其工作，您需要在配置中全局注册类型处理程序（这是一种限制）。
在你的情况下，添加mybatis.type-handlers-package=my.packageapplication.properties 就足够了。

一旦类型处理程序被全局注册，您就可以省略typeHandler在大多数情况下，在您的映射器中。

@Select("SELECT id, name FROM t_service s")
@Results(value = {
  @Result(column = "id", property = "id"),
  @Result(column = "name", property = "name"),
  @Result(property = "rates", column = "id",
    javaType = List.class, many = @Many(select = "getAllRates"))
})
List<Service> findAll();

@Select("SELECT date_from, date_to, currency FROM t_rate where t_rate.service_id = #{serviceId}")
@Results(value = {
  @Result(property = "dateFrom", column = "date_from"),
  @Result(property = "dateTo", column = "date_to"),
  @Result(property = "currency", column = "currency")
})
List<Rate> getAllRates(@Param("serviceId") UUID serviceId);

类型处理程序也可以更简单一些。

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.UUID;

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedTypes;

// no @MappedJdbcTypes
@MappedTypes(UUID.class)
public class UuidTypeHandler extends BaseTypeHandler<UUID> {
  @Override
  public void setNonNullParameter(PreparedStatement ps, int i, UUID parameter, JdbcType jdbcType) throws SQLException {
    ps.setObject(i, parameter); // no 3rd arg
  }

  @Override
  public UUID getNullableResult(ResultSet rs, String columnName) throws SQLException {
    return rs.getObject(columnName, UUID.class);
  }

  @Override
  public UUID getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
    return rs.getObject(columnIndex, UUID.class);
  }

  @Override
  public UUID getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
    return cs.getObject(columnIndex, UUID.class);
  }
}