我正在尝试使用 $
update运算符更新数组中的元素 . 该文档包含2个数组字段,我必须查询两个以选择正确的文档 .
该集合名为 locations
,文档如下所示:
{
"_id" : "XqEQYpitGFG3nnf3C",
"wallpapers" : [
{
"_metadata" : {
"master" : "vwb22W4MhkqtvAp89",
"isMaster" : false
},
"role" : "master",
"_id" : ""
},
{
"_metadata" : {
"master" : "vwb22W4MhkqtvAp89",
"isMaster" : false
},
"role" : "clone",
"_id" : ""
},
{
"_metadata" : {
"master" : "vwb22W4MhkqtvAp89",
"isMaster" : false
},
"role" : "pod",
"_id" : ""
}
],
"ancestors" : [
"vwb22W4MhkqtvAp89",
"tqzqfum9uMs47xcHW",
"b4d83aqTkq6TGvXts",
"XqEQYpitGFG3nnf3C"
]
}
更新运算符如下所示:
db.getCollection('locations').update(
{
"ancestors": "b4d83aqTkq6TGvXts",
"wallpapers": {
"$elemMatch": {
"role": "clone",
"_metadata.master": "vwb22W4MhkqtvAp89"
}
}
},
{
"$set": {
"wallpapers.$": {
"_id": "D33WNZh7Bg4itPdhk",
"_metadata": {
"master": "b4d83aqTkq6TGvXts",
"isMaster": false
},
"role": "clone"
}
}
}
)
所以我想替换 wallpapers
数组中的元素 . 但是,我得到的结果是:
{
"_id" : "XqEQYpitGFG3nnf3C",
"wallpapers" : [
{
"_metadata" : {
"master" : "vwb22W4MhkqtvAp89",
"isMaster" : false
},
"role" : "master",
"_id" : ""
},
{
"_metadata" : {
"master" : "vwb22W4MhkqtvAp89",
"isMaster" : false
},
"role" : "clone",
"_id" : ""
},
{
"_id" : "D33WNZh7Bg4itPdhk",
"_metadata" : {
"master" : "b4d83aqTkq6TGvXts",
"isMaster" : false
},
"role" : "clone"
}
],
"ancestors" : [
"vwb22W4MhkqtvAp89",
"tqzqfum9uMs47xcHW",
"b4d83aqTkq6TGvXts",
"XqEQYpitGFG3nnf3C"
]
}
所以它取代了错误的元素 . 似乎 .$
引用的位置是 ancestors
字段的选择器中的位置 .
这是一个错误还是一个限制?有没有解决方案(例如 .$1
和 .$2
?
我正在使用MongoDB 3.2.6 .
1 回答
在update operation query中,使用dot notation作为: