使用MongoDB-Java驱动程序从数组中删除条目

Question

我有JSON喜欢:

{ 
    "_id" : "1",
    "_class" : "com.model.Test",
    "itemList" : [
        {
            "itemID" : "1",
            "itemName" : "Foo",
            "resources" : [ 
                { 
                    "resourceID" : "1",
                    "resourceName" : "Foo Test1"
                 }, {
                    "resourceID" : "2",
                    "resourceName" : "Foo Test2"
                 }
             ]
        }
    ]
}

我需要能够删除itemList的记录之一.我做了以下事情:

public void removeItemByID(String docID, String itemID) throws Exception {
    MongoOperations mongoOperations = mongoConfiguration.getMongoTemplate();
    Query query = new   Query(where("_id").is(docID).and("itemList.itemID").is(itemID));
    mongoOperations.remove(query, Item.class);

}

这种方法不起作用.但是,当我使用带有$ pull方法的BasicDBObject时,它工作正常!这些方法有什么区别!

Answer 1

如果你想删除一个数组我通常使用以下内容:

BasicDBObject match = new BasicDBObject("_id", "1"); // to match your document
BasicDBObject update = new BasicDBObject("itemList", new BasicDBObject("itemID", "1"));
coll.update(match, new BasicDBObject("$pull", update));

Answer 2

模板中的 remove 方法删除文档。如果要从数组中删除项目，则必须使用 pull。就像是

MongoOperations mongoOperations = mongoConfiguration.getMongoTemplate();
Query query = new Query(where("_id").is(docID).and("itemList.itemID").is(itemID));
Update update = new Update().pull("itemList", new BasicDBObject("itemID", "1"));
mongoOperations.updateFirst(query, update, Item.class);