英文:
Mongodb recursive search for array of objects
问题
我有一个树形结构，看起来像这样：
{
"_id" : ObjectId("59aebe21f002a8556ca78310"),
"fid" : ObjectId("59aebe216b96002252a89d7b"),
"pr" : [
],
"ch" : [
{
"_id" : ObjectId("59aebe326b96002252a89d7d"),
"trashed" : false
},
{
"_id" : ObjectId("59aebe376b96002252a89d7f"),
"trashed" : false
}
]
}
{
"_id" : ObjectId("59aebe33f002a8556ca78347"),
"fid" : ObjectId("59aebe326b96002252a89d7d"),
"pr" : [
{
"_id" : ObjectId("59aebe216b96002252a89d7b"),
"trashed" : false
}
],
"ch" : [
{
"_id" : ObjectId("59aebe3b6b96002252a89d81"),
"trashed" : false
}
]
}
其中 fid 是文件夹的ID，ch 是文件夹的子文件夹，所以我想要进行递归搜索以获取文件夹和文件的树形结构。
在我的情况下，我使用了 $graphLookup 来进行递归搜索，但结果中我也得到了其他文件夹。
pipeline := []bson.M{
{"$match": bson.M{"fid": id}},
{"$graphLookup": bson.M{
"from": "tree",
"startWith": "$fid",
"connectFromField": "fid",
"connectToField": "ch._id",
"as": "parents",
}},
{"$match": bson.M{"ch.trashed": false}},
}
Connection.Session.DB("cctv_storage").C("tree").Pipe(pipeline).All(&tData)
我的项目是基于 Golang 的。
英文:
I have a tree structure look like this
{
"_id" : ObjectId("59aebe21f002a8556ca78310"),
"fid" : ObjectId("59aebe216b96002252a89d7b"),
"pr" : [
],
"ch" : [
{
"_id" : ObjectId("59aebe326b96002252a89d7d"),
"trashed" : false
},
{
"_id" : ObjectId("59aebe376b96002252a89d7f"),
"trashed" : false
}
]
}
{
"_id" : ObjectId("59aebe33f002a8556ca78347"),
"fid" : ObjectId("59aebe326b96002252a89d7d"),
"pr" : [
{
"_id" : ObjectId("59aebe216b96002252a89d7b"),
"trashed" : false
}
],
"ch" : [
{
"_id" : ObjectId("59aebe3b6b96002252a89d81"),
"trashed" : false
}
]
}
the fid is a folder id and the ch is the children of folder , so I want to do a recursive search to get tree of the folders and files.
In my case I have a used $graphLookup to do a recursive search but as a result I am getting other folders too
pipeline := []bson.M{
{"$match": bson.M{"fid": id}},
{"$graphLookup": bson.M{
"from": "tree",
"startWith": "$fid",
"connectFromField": "fid",
"connectToField": "ch._id",
"as": "parents",
}},
{"$match": bson.M{"ch.trashed": false}},
}
Connection.Session.DB("cctv_storage").C("tree").Pipe(pipeline).All(&tData)
My project based on Golang.
答案1
得分: 1
我认为你需要先使用$unwind，然后再使用$graphLookup，这样你就可以进行递归搜索，就像这样：
var tData struct {
Id bson.ObjectId `bson:"_id"`
Child [][]bson.ObjectId `bson:"child"`
}
pipeline := []bson.M{
{"$unwind": bson.M{
"path": "pr",
"preserveNullAndEmptyArrays": true,
}},
{"$graphLookup": bson.M{
"from": "tree",
"startWith": "$fid",
"connectFromField": "fid",
"connectToField": "pr._id",
"as": "child",
}},
{"$match": bson.M{"fid": id}},
{"$group": bson.M{"_id": id, "child": bson.M{"$addToSet": "$child.fid"}}},
}
Connection.Session.DB("cctv_storage").C("tree").Pipe(pipeline).One(&tData)
因此，你将获得根文件夹的id以及子文件夹的id。
英文:
I think you need to use $unwind for first, than $graphLookup, so you need to do a recursive search look like this
var tData struct {
Id bson.ObjectId `bson:"_id"`
Child [][]bson.ObjectId `bson:"child"`
}
pipeline := []bson.M{
{"$unwind": bson.M{
"path": "$pr",
"preserveNullAndEmptyArrays": true,
}},
{"$graphLookup": bson.M{
"from": "tree",
"startWith": "$fid",
"connectFromField": "fid",
"connectToField": "pr._id",
"as": "child",
}},
{"$match": bson.M{"fid": id}},
{"$group": bson.M{"_id": id, "child": bson.M{"$addToSet": "$child.fid"}}},
}
Connection.Session.DB("cctv_storage").C("tree").Pipe(pipeline).One(&tData)
So as a result you will get the id of the root folder and the ids of children
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