从另一个集合中删除dbref元素

Question

我有一个包含元素的集合会话

{
    "_id" : NumberLong(1),
    "_class" : "cws.CWSession",
    "title" : "java ",
    "description" : "apprendre à programmer en java"  
}

{
    "_id" : NumberLong(2),
    "_class" : "cws.CWSession",
    "title" : "Git",
    "description" : "Formation Git"    
}

我还有一个包含CWSession的dbRed的集合：

{
"_id" : NumberLong(2),
"_class" : "cws.CollaborativeWs",    
"title" : "AngularJS",
"description" : "AngularJS",
"cws" : [ 
    {
        "$ref" : "cwsession",
        "$id" : NumberLong(1)
    },
    {
        "$ref" : "cwsession",
        "$id" : NumberLong(2)
    }
]
}

{
"_id" : NumberLong(3),
"_class" : "cws.CollaborativeWs",    
"title" : "Java",
"description" : "principes java ",
"cws" : [ 
    {
        "$ref" : "cwsession",
        "$id" : NumberLong(3)
    }
]
}

我使用mongo模板删除会话

mongoTemplate.remove(new Query(Criteria.where("_id").is(id)), CWSession.class);

它工作正常，会话在第一个集合中被删除，但仍然在第二个集合中，您能告诉我我可以使用什么来删除第二个集合中的引用吗？提前谢谢你。

public void deleteSessionfromCW(String idCW, String idS){
    Query query = new Query(where("_id").is(idCW).and("cws.id").is(id));
    Update update = new Update().pull("cws", new BasicDBObject("id", "1"));
    mongoTemplate.updateFirst(query, update, Item.class);
}