相关疑难解决方法(0)

我在DBRef上遇到了一些麻烦,看看这个案例:

db.fruit.save ({"_id" : "1" , "name" : "apple"});
db.fruit.save ({"_id" : "2" , "name" : "grape"});
db.fruit.save ({"_id" : "3" , "name" : "orange"});
db.fruit.save ({"_id" : "4" , "name" : "pineapple"});

db.basket.save ({"_id" : "1", "items" : [
    {"$ref" : "fruit", "$id" : "1", "quantity" : 5},
    {"$ref" : "fruit", "$id" : "3", "quantity" : 10}
]})

现在,让我们找到"篮子"系列:

> db.basket.find ()
{ "_id" : "1", "items" : [
    {
        "$ref" : "fruit",
        "$id" : "1"
    },
    {
        "$ref" …