如何在MyBatis中将参数从@Result传递给@One

Question

I am working with temporal versioned data, so most of my queries require both a point in time and a group id. How can I pass these to my nested many to one queries?

For example:

@Select("select * "
        + "from type1 "
        + "where effective_date <= #{0, typeHandler=...} "
        + "and termination_date > #{0, typeHandler=...}")
@Results({
    @Result(property = "id", column = "id"),
    @Result(property = "groupId", column = "group_id"),
    // ...
    @Result(property = "type2", column = "type2_group_id", javaType = Type2.class,
        one = @One(select = "com...mapper.Type2Mapper.getByGroupId")) // **
    // ...
})

Such that Type2Mapper has:

@Select(...)
Type2 getByGroupId(Date date, Long groupId);

The line identified by // ** must pass both the Date passed into it along with the type2_group_id. Obviously I can rearrange things or whatever it takes to make this work, I'm just hoping I don't have to go to the point of changing my models to include a Long type2GroupId that I then populate the type2 instance after the fact.

Any thoughts?

Answer 1

I could not find any way to do this, so I added support for it: https://github.com/mybatis/mybatis-3/pull/203

@Result(property = "type2", column = "type2_group_id", javaType = Type2.class,
    one = @One(select = "com...mapper.Type2Mapper.getByGroupId",
            parameterProvider = @OneParameterProvider(
                    type = TemporalParameterProvider.class, method = "getParametersWithDate"
            )))

And:

public class TemporalParameterProvider {
    public Object getParametersWithDate(Object value, Class<?> type, List<Object> originalParameters) {
        Map<String, Object> parameters = new HashMap<String, Object>();
        parameters.put("0", originalParameters.get(0));
        parameters.put("1", value);
        return parameters;
    }
}

This could also be used to query off of calculations from the original column value, and hopefully for other use cases as well.