Example of a Spring Data MongoDB data structure that causes the aggregation framework in Spring Data MongoDB 1.3.0.RC1 to fail.

DailyUserAggregate.groovy

@Document
class DailyUserAggregate {
    @Id
    @Field( value = '_id' )
    String id

    @Field( value = 'student' )
    Student student = new Student()

    // other fields removed
}

Spock Excerpt

        when: 'report is run'
        // the attributes to filter on
        String INSTANCE = 'ONE'
        String NODE = 'ONE'
        String ORGANIZATION = 'ONE'
        String SCHOOL_HOUSE = 'ONE'
        String CLASS_CODE = 'ONE'
        long START_DATE = 1
        long STOP_DATE = 30

        TypedAggregation<DailyUserAggregate> aggregation = newAggregation( DailyUserAggregate,  match( where( 'instance' ).is( INSTANCE ).and( 'node' ).is( NODE ).and( 'organization' ).is( ORGANIZATION ).and( 'schoolHouses' ).is( SCHOOL_HOUSE ).and( 'student.classParticipation.code' ).is( CLASS_CODE ).and( 'dateCode' ).gte( START_DATE ).lte( STOP_DATE ) ), group( 'student.code' ).sum( 'student.totalLessonSessionCount' ).as( 'total-session-count' ) )
        AggregationResults<LearnerActivityReport> result = template.aggregate( aggregation, LearnerActivityReport )
        List<LearnerActivityReport> aggregate = result.getMappedResults()

// NOTICE the group( 'student.code' ) clause, this is causing the error because I'm trying to group on a property of a sub-object.

stack trace

org.springframework.data.mapping.PropertyReferenceException: No property code found for type org.kurron.domain.DailyUserAggregate
	at org.springframework.data.mapping.PropertyPath.<init>(PropertyPath.java:75)
	at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:327)
	at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:307)
	at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:271)
	at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:245)
	at org.springframework.data.mongodb.core.aggregation.TypeBasedAggregationOperationContext.getReference(TypeBasedAggregationOperationContext.java:81)
	at org.springframework.data.mongodb.core.aggregation.GroupOperation.toDBObject(GroupOperation.java:284)
	at org.springframework.data.mongodb.core.aggregation.Aggregation.toDbObject(Aggregation.java:228)
	at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1256)
	at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1233)
	at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1222)
	at org.kurron.domain.DataPopulationLearningTest.execute learner activity report(DataPopulationLearningTest.groovy:158)

Student.groovy

class Student {
    @Field( value = 'student-id' )
    String code

    // other fields removed
}