Mongodb查询所有二级单据是否有子单据满足条件

我正试图从以下第二级子文档中的通讯簿中获取

默认\u账单

{ 
        "_id" : ObjectId("5a841ac387c7d70ad36f5ce2"), 
        "user_type" : "retail", 
        "first_name" : "Mayank", 
        "last_name" : "Garg", 
        "addressbook" : {
            "5a93d64187c7d71562433a22" : {
                "consignee_name" : "Jerry Day", 
                "first_name" : "Cole", 
                "last_name" : "Bean", 
                "mobile" : "33333333333333", 
                "street_address" : "", 
                "street_address2" : "", 
                "city" : "", 
                "zip_code" : "58694", 
                "select_country" : "India", 
                "default_billing" : true
            }, 
            "5a9400f887c7d70aac2908e2" : {
                "consignee_name" : "Jerry Day", 
                "first_name" : "Cole", 
                "last_name" : "Bean", 
                "mobile" : "33333333333333", 
                "street_address" : "", 
                "street_address2" : "", 
                "city" : "",  
                "select_state" : "Delhi", 
                "zip_code" : "78004", 
                "select_country" : "India"
            }
        }
    }

我试过这个

---

您可以使用

$objectToArray

创建对象数组，对数组应用过滤器，然后使用

$arrayToObject

将数组转换回对象。如果在文档中找不到匹配项，则addressbook将是一个空对象。我们可以添加

$match

作为下一阶段，以便在需要时删除它们

db.collection.aggregate([{
    $addFields: {
        addressbook: {
            $objectToArray: '$addressbook'
        }
    }
}, {
    $addFields: {
        addressbook: {
            $filter: {
                input: '$addressbook',
                as: 'ab',
                cond: {$eq: ['$$ab.v.default_billing', true]}
            }
        }
    }
}, {
    $addFields: {
        addressbook: {
            $arrayToObject: '$addressbook'
        }
    }
}]);

---

$elemMatch

仅对阵列有效。您是否愿意使用聚合？是的，这对我有效

db.collection.aggregate([{
    $addFields: {
        addressbook: {
            $objectToArray: '$addressbook'
        }
    }
}, {
    $addFields: {
        addressbook: {
            $filter: {
                input: '$addressbook',
                as: 'ab',
                cond: {$eq: ['$$ab.v.default_billing', true]}
            }
        }
    }
}, {
    $addFields: {
        addressbook: {
            $arrayToObject: '$addressbook'
        }
    }
}]);