语法为dbref http://www.mongodb.org/display/DOCS/Database+References#DatabaseReferences-DBRef is
{ $ref : <collname>, $id : <idvalue>[, $db : <dbname>] }
但是您在 dbref 中添加了不支持的数量字段。那就是问题所在。把它带到外面
db.basket.save ({"_id" : "1", "items" : [
{"quantity" : 5 , item : {"$ref" : "fruit", "$id" : "1"}},
{"quantity" : 10, item : {"$ref" : "fruit", "$id" : "3"}}
]})
什么样的样子(吓人)
{
"_id" : "1",
"items" : [
{
"quantity" : 5,
"item" : {
"$ref" : "fruit",
"$id" : "1"
}
},
{
"quantity" : 10,
"item" : {
"$ref" : "fruit",
"$id" : "3"
}
}
]
}
但我的建议是,完全放弃 dbref,只使用像这样的简单结构
db.basket.save ({"_id" : "1",items:[
{item_id:"1",quantity:50},
{item_id:"3",quantity:10}
]})
这更干净,看起来像
{
"_id" : "1",
"items" : [
{
"item_id" : "1",
"quantity" : 50
},
{
"item_id" : "3",
"quantity" : 10
}
]
}