英文:
Mgo (mongo for go) support for materialized paths?
问题
使用BSON和Mgo（用于Go的强大MongoDB驱动程序），如何实现材料化路径（Materialized paths）？
材料化路径在MongoDB文档中有详细说明。材料化路径旨在为多层嵌套数据提供类似树状结构的表示。
使用纯JavaScript，命令如下（来自文档1）：
db.categories.insert( { _id: "Books", path: null } )
db.categories.insert( { _id: "Programming", path: ",Books," } )
db.categories.insert( { _id: "Databases", path: ",Books,Programming," } )
db.categories.insert( { _id: "Languages", path: ",Books,Programming," } )
创建了名为'categories'的集合，并插入了以下条目：
Books > Programming > Databases
Books > Programming > Languages
可以使用以下查询语句进行查询：
db.categories.find( { path: /,Programming,/ } )
将找到两个条目，它们都是Programming的后代。
如何使用Mgo和BSON来实现这个功能？
在Mgo文档中没有这样的说明。我尝试了以下方法：
result := []bson.M{}
database.C("categories").Find(bson.M{"path": "/,Programming,/"}).All(&result)
fmt.Println(result)
但只返回一个空数组[]。
有没有Go语言和MongoDB方面的专家可以给我指点一下？
谢谢！
英文:
With BSON and Mgo(rich mongodb driver for go), how would one approach implementing materialized paths?
Materialized paths are documented here on the mongo docs. Materialized paths are designed to provide a tree-like structure for multiple levels of nested data.
With plain javascript, the command are as follows (from the documentation):
db.categories.insert( { _id: "Books", path: null } )
db.categories.insert( { _id: "Programming", path: ",Books," } )
db.categories.insert( { _id: "Databases", path: ",Books,Programming," } )
db.categories.insert( { _id: "Languages", path: ",Books,Programming," } )
Created collection 'categories' with the following entries
Books > Programming > Databases
Books > Programming > Languages
And can be queried using:
db.categories.find( { path: /,Programming,/ } )
Will find the two entries which are both decendants of programming.
How do I implement this using Mgo and BSON?
There is no such documentation in the Mgo docs. I have tried attempts such as
result := []bson.M{}
database.C("categories").Find(bson.M{"path": "/,Programming,/"}).All(&result)
fmt.Println(result)
Only to return an empty array []
Any gophers and mongo lovers to enlighten me here?
Thanks!
答案1
得分: 1
请看一下 mgo/bson 文档中的这部分内容：http://godoc.org/labix.org/v2/mgo/bson#RegEx
它应该是这样的：
database.C("categories").Find(bson.M{"path": &bson.RegEx{Pattern: ",Programming,", Options: "i"}}).All(&result)
英文:
Checkout this part in mgo/bson documentation: http://godoc.org/labix.org/v2/mgo/bson#RegEx
It should probably look like this
database.C("categories").Find(bson.M{"path": &bson.RegEx{Pattern: ",Programming,", Options: "i"}}).All(&result)
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