使用mongoose将单个文档保留在mongoDB集合中 [英] Keep a single document in mongoDB collection using mongoose

问题描述

我创建了一个集合，但是应该在其中保留一个文档. 如何确保猫鼬模式中只有一个文档?

I created a collection but that one should keep a single document inside. How do I ensure that there is a single document in mongoose schema?

推荐答案

您可以创建封顶"集合，可以在其中设置文档限制，也可以在其中存储文档.

You can create "capped" collections, where you can set limit of documents, you can store in it.

但是，这不会阻止添加另一个文档(不确定，是否需要该功能)-如果添加另一个文档，则旧文档将被删除.

It does not however prevent adding another document (not sure, if you need that functionality) - if you add another document, the old one would be deleted.

db.createCollection('mycappedcol',{capped: true, size:999999, max:1})

您也不能从加盖的收藏夹中删除文档，只能将它们替换为新的收藏夹或删除整个收藏夹.

Also you cant delete documents from capped collections, you can only replace them with new ones or drop the whole collection.

PS:在设置上限的集合中，您必须指定大小(以字节为单位)，这也是一个限制(集合不能大于指定的大小).如果您不关心大小，而只关心限制，则只需将大小设置为足够大即可.

PS : In capped collections, you have to specify size in bytes, which is also a limit (collection cant be bigger than specified size). If you do not care about size, but you care only about limit, just set size big enough.

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