如何指定从查询中排除文档的条件? [英] How do I specify criteria for excluding documents from a query?

问题描述

这似乎是一个简单的问题，但我还没有找到答案: 我正在使用MongoDB，我想执行一个查询，在其中提供搜索条件，但是我也想解决一个例外，即根据条件排除某些文档.例如，想象一个具有字段name，age和gender的集合.

This seems like a simple enough question but I haven't found an answer: I'm using MongoDB and I want to perform a query in which I provide search criteria, but I also want to carve out an exception where certain documents are excluded based on criteria. For example, imagine a collection with the fields name, age and gender.

是否正在检索特定年龄以下的所有人?容易:<collection>.find({'age':{'$lt':<maxAge>}}) 检索特定年龄以下的所有女性?小菜一碟:<collection>.find({'gender':female, 'age':{'$lt':<maxAge>}})

Retrieving everyone below a certain age? Easy: <collection>.find({'age':{'$lt':<maxAge>}}) Retrieving all females below a certain age? Piece of cake: <collection>.find({'gender':female, 'age':{'$lt':<maxAge>}})

但是如何检索所有人，除非他们是[女性且未满一​​定年龄的人]?您可以使用'$ ne'运算符轻松否定特定字段，但是我该如何否定所有符合一组条件的人呢?

But what about retrieving everyone, except if they are [female and below a certain age?]. You can easily negate a specific field with the '$ne' operator, but how do I negate everyone who matches a set of criteria?

推荐答案

您必须应用布尔逻辑，才能将AND分别转换为每个项的否定的OR:

You would have to apply boolean logic to invert the AND into an OR of the negation of each term individually:

collection.find({$or: [{age: {$gte: maxAge}}, {gender: {$ne: 'female'}}]})

或

collection.find({$or: [{age: {$not: {$lt: maxAge}}}, {gender: {$ne: 'female'}}]})

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