Question

在下面的mongo集合中，如何过滤包含密钥cat1的文档？

{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key1_cat1": "val1"
}
{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key1_cat2": "val2"
}
{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key2_cat1": "val3"
}
{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key2_cat2": "val4"
}

我正在寻找像collection.find({"$key_contains":"cat1"})这样的东西，它应该过滤doc1和doc2并输出为

{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key1_cat1": "val1"
}
{
    "_id" : ObjectId("xxxxxxxxxx"),
    "key2_cat1": "val3"
}

Answer 1

我相信它不能直接在Mongo中完成。但我们可以使用聚合来实现这一点，使用objectToArray

collection.aggregate([{
    '$project': {
        modifiedFormat: {
            $objectToArray: '$$ROOT'  // converts your object to array format [{k:, v:}, {k:, v:}]
        }
    }
}, {
    $match: {
        'modifiedFormat.k': {
            $regex: 'cat1' // your search on key(k)
        }
    }
}, {
    $project: {
        oldFormat: {
            $arrayToObject: '$modifiedFormat' // Making array to object again
        }
    }
}, {
    $replaceRoot: {
        newRoot: '$oldFormat' // replaceRoot to bring in the old format
    }
}])

MongoDB - 如何过滤包含键的文档

1 个答案: