Spring MongoDB ArrayOperators过滤器不起作用

Question

我有用于mongodb的java pojo类。我正在尝试过滤列表。我正在尝试使用Mongodb聚合。

public List<CourseDetails> aggregationTest(Student student){
    MatchOperation matchOperation = Aggregation.match(new Criteria("students").is(student));
    ArrayOperators.Filter filter = filter("students").as("student")
                                                     .by(ComparisonOperators.Eq.valueOf("student").equalToValue("student"));

    ProjectionOperation projectionOperation = project("course","teacher","students","examPapers").and(filter)
                                                                                                 .as("Courses");
    AggregationResults<CourseDetails> courseDetailsAggregationResults =
            mongoTemplate.aggregate(newAggregation(matchOperation,projectOperation),
                    CourseDetails.class,CourseDetails.class);


    return courseDetailsAggregationResults.getMappedResults();
}

我希望学生名单上有一名学生。但是我越来越多。我做错了。