问题描述
我知道这可能是一个愚蠢的问题，但我在一本电子书中读到，MongoDB 插入中有一个 upsert 选项.我找不到关于此的适当文档.有人可以教育我吗?
I know this may be a silly question, but I read on an e-book that there is an upsert option in MongoDB insert. I couldn't find proper documentation about this. Can someone educate me about this?
推荐答案
因为 upsert 被定义为当没有文档符合查询条件时创建一个新文档" insert 命令中没有 upserts 的地方.它是 update 命令的一个选项.如果您执行如下命令，它将作为 update、如果有匹配query 的文档，或者作为insert 以update 描述的文档作为参数一>.
Since upsert is defined as operation that "creates a new document when no document matches the query criteria" there is no place for upsertsin insert command. It is an option for the update command. If you execute command like below it works as an update, if there is a document matching query, or as an insert with document described by update as an argument.
db.collection.update(query, update, {upsert: true})
MongoDB 3.2 添加了 replaceOne:
MongoDB 3.2 adds replaceOne:
db.collection.replaceOne(query, replacement, {upsert: true})
具有类似行为，但其 replacement 不能包含更新操作符.
which has similar behavior, but its replacement cannot contain update operators.
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