Map multiple source fields to same type target fields with Mapstruct

Question

Consider the following POJOs:

public class SchedulePayload {
    public String name;
    public String scheduler;
    public PeriodPayload notificationPeriod;
    public PeriodPayload schedulePeriod;
}

private class Lecture {
    public ZonedDateTime start;
    public ZonedDateTime end;
}

public class XmlSchedule {
    public String scheduleName;
    public String schedulerName;
    public DateTime notificationFrom;
    public DateTime notificationTo;
    public DateTime scheduleFrom;
    public DateTime scheduleTo;
}

public class PeriodPayload {
    public DateTime start;
    public DateTime finish;
}

Using MapStruct, I created a mapper that maps XmlSchedule to a SchedulePayload. Due to "business" "logic", I need to constrain notificationPeriod and schedulePeriod to a Lecture's start and end field values. Here is what I've come up to, using another class:

@Mapper(imports = { NotificationPeriodHelper.class })
public interface ISchedulePayloadMapper
{
    @Mappings({
        @Mapping(target = "name", source = "scheduleName"),
        @Mapping(target = "scheduler", source = "schedulerName"),
        @Mapping(target = "notificationPeriod", expression = "java(NotificationPeriodHelper.getConstrainedPeriod(xmlSchedule, notificationFrom, notificationTo))"),
        @Mapping(target = "schedulePeriod", expression = "java(NotificationPeriodHelper.getConstrainedPeriod(xmlSchedule, scheduleFrom, scheduleTo))")
    })
    SchedulePayload map(XmlSchedule xmlSchedule, Lecture lecture);

}

Is there any way this can be achieved in another way (i.e. another mapper, decorators, etc.)? How can I pass multiple values (xmlSchedule, lecture) to a mapper?

agudian · Accepted Answer · 2016-06-08 19:22:32Z

25

What you can do is create an @AfterMapping method to populate those parts manually:

@Mapper
public abstract class SchedulePayloadMapper
{
    @Mappings({
        @Mapping(target = "name", source = "scheduleName"),
        @Mapping(target = "scheduler", source = "schedulerName"),
        @Mapping(target = "notificationPeriod", expression = "java(NotificationPeriodHelper.getConstrainedPeriod(xmlSchedule, notificationFrom, notificationTo))"),
        @Mapping(target = "schedulePeriod", expression = "java(NotificationPeriodHelper.getConstrainedPeriod(xmlSchedule, scheduleFrom, scheduleTo))")
    })
    public abstract SchedulePayload map(XmlSchedule xmlSchedule, Lecture lecture);

    @AfterMapping
    protected void addPeriods(@MappingTarget SchedulePayload result, XmlSchedule xmlSchedule, Lecture lecture) {
        result.setNotificationPeriod(..);
        result.setSchedulePeriod(..);
    }
}

Alternatively, you can place the @AfterMapping method in another class that is referenced in @Mapper(uses = ..) or you can use a Decorator (using the mechanisms MapStruct provides, or of your dependency injection framework if you use one).

answered Jun 8, 2016 at 19:22

agudian

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6 Comments

giannoug Over a year ago

@AfterMapping seems a clean approach! Thanks!

Robert Gabriel Over a year ago

Just out of curiosity, is there a way to handle immutable objects?

Filip Over a year ago

@RobertGabriel since the latest (1.3.0.Beta1) MapStruct can use Builders to map into Immutable objects. In the answer of this question, this would mean that you can have the builder for SchedulePayload in the @AfterMapping

Robert Gabriel Over a year ago

Yes, you are right. A colleague told me the same thing yesterday. :)

Jacob van Lingen Over a year ago

Note when using the builder pattern in your objects, the @MappingTarget should be of type YourBuilder instead of your response type!

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