MongoDB仅按数组属性过滤(如果存在) [英] MongoDB filter by array property only if it exists

问题描述

我的数据库对象有一个名为tags的可选属性，它是一个字符串数组.我想编写一个查询，如果它们符合以下条件之一，则返回对象:

My database object has an optional property named tags which is a string array. I want to write a query that returns objects if they match one of these conditions:

1. 他们没有tags属性.
2. 它们具有标签属性，该属性至少在另一个称为queryTags
的数组中包含一项

1. They don't have a tags property.
2. They have a tags property that has at least one item included in another array called queryTags

通过阅读文档，我想到了以下内容，但它不起作用:

From reading the documentation I came up with the following but it doesn't work:

let query = {
    tags: { '$or': [{'$exists': false}, {'$in': queryTags}]}
}

推荐答案

$or是顶级运算符，因此您的查询必须是:

$or is a top-level operator, so your query needs to be:

let query = {
    '$or': [{tags: {'$exists': false}}, {tags: {'$in': queryTags}}]
}

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