MongoDB 插入 key 为 '$'(美元)

Question

我正在尝试插入一个包含 json 对象的集合，该对象包含以“$”开头的键(例如:“$count”)。我读了mongodb v3.0 FAQ's他们提到这不是一把 key 。有没有什么迂回的方法插入这样的 key 并将其取回？

Answer 1

Field names cannot contain dots (i.e. .) or null characters, and they must not start with a dollar sign (i.e. $).

<小时/>

In some cases, you may wish to build a BSON object with a user-provided key. In these situations, keys will need to substitute the reserved $ and . characters. Any character is sufficient, but consider using the Unicode full width equivalents: U+FF04 (i.e. “＄”) and U+FF0E (i.e. “．”).

不推荐，但你可以尝试这个:

dollar = "\uFF04";
＄
dot = "\uFF0E"
．

db.test.save({[dollar]:dot})
WriteResult({ "nInserted" : 1 })
db.test.save({[dot]:dollar})
WriteResult({ "nInserted" : 1 })

db.test.find()
{ "_id" : ObjectId("58256b0f9934a5d1c696c456"), "＄" : "．" }
{ "_id" : ObjectId("58256d359934a5d1c696c457"), "．" : "＄" }