【发布时间】：2021-03-09 14:41:49
【问题描述】：
问题是：打印所有住宿的列表，首先按价格排序，然后按提供的便利设施数量。 但是，有两个问题，第一个是 price 是一个以 $ 开头的字符串，必须先将其转换为整数才能正确排序，另一个问题，我不知道如何计算属性的数量每个文件的便利设施。
My JSON is like this:
[
{
"_id": "5bf31f8c856a12c73c888cee",
"index": 0,
"guid": "f99844b5-7ecd-4c90-860f-b79a742fcac1",
"isActive": true,
"registered": "2012-06-14T02:14:30 -02:00",
"host": {
"name": "Grimes",
"surname": "Terrell",
"gender": "male",
"age": 55,
"picture": "https://api.adorable.io/avatars/285/GrimesTerrell.png",
"languages": [
"spanish",
"slovenian",
"english"
],
"contact": {
"company": "QUANTALIA",
"email": "grimesterrell@quantalia.com",
"phone": "+1 (987) 474-3543"
},
"reviews": [
{
"reviewer": "Mae Ryan",
"date": "2015-06-01T02:41:46 -02:00",
"helpful": 8,
"kind": 1,
"responsive": 5
},
{
"reviewer": "Nixon Johnson",
"date": "2016-02-08T10:35:12 -01:00",
"helpful": 1,
"kind": 1,
"responsive": 9
},
{
"reviewer": "Dorothy Copeland",
"date": "2016-07-17T12:44:31 -02:00",
"helpful": 3,
"kind": 3,
"responsive": 4
},
{
"reviewer": "Kathleen Roth",
"date": "2014-12-26T04:38:36 -01:00",
"helpful": 10,
"kind": 3,
"responsive": 5
},
{
"reviewer": "Hallie Hart",
"date": "2016-02-14T10:21:50 -01:00",
"helpful": 9,
"kind": 4,
"responsive": 9
}
]
},
"lodging": {
"price": "$86",
"address": {
"street": "645 Louisa Street",
"city": "Fairhaven",
"state": "Nebraska",
"coordinates": [
5.439653,
30.761532
]
},
"amenities": {
"parking": true,
"petsAllowed": true,
"airConditioning": true,
"elevator": true
},
"reviews": [
{
"reviewer": "Susanne Walton",
"date": "2018-03-20T04:50:18 -01:00",
"cleanliness": 8,
"location": 1,
"food": 10
},
{
"reviewer": "Henrietta Manning",
"date": "2017-12-14T07:05:46 -01:00",
"cleanliness": 10,
"location": 5,
"food": 1
},
{
"reviewer": "Newman West",
"date": "2018-05-07T05:23:55 -02:00",
"cleanliness": 9,
"location": 10,
"food": 6
},
{
"reviewer": "Brennan Rowland",
"date": "2016-09-20T04:49:15 -02:00",
"cleanliness": 10,
"location": 1,
"food": 8
},
{
"reviewer": "Beulah Lambert",
"date": "2016-04-20T11:51:43 -02:00",
"cleanliness": 4,
"location": 8,
"food": 9
},
{
"reviewer": "Joseph Mcdowell",
"date": "2015-02-10T12:14:20 -01:00",
"cleanliness": 7,
"location": 9,
"food": 3
}
]
}
},
{
"_id": "5bf31f8c20b3acacc2194faa",
"index": 1,
"guid": "7d65ed39-13d0-4121-bacd-3b6e1c1daa17",
"isActive": true,
"registered": "2016-04-22T08:54:50 -02:00",
"host": {
"name": "Schultz",
"surname": "French",
"gender": "male",
"age": 24,
"picture": "https://api.adorable.io/avatars/285/SchultzFrench.png",
"languages": [
"spanish",
"polish"
],
"contact": {
"company": "ORBEAN",
"email": "schultzfrench@orbean.com",
"phone": "+1 (972) 497-2462"
},
"reviews": [
{
"reviewer": "Prince Berg",
"date": "2017-11-10T01:18:41 -01:00",
"helpful": 5,
"kind": 5,
"responsive": 6
}
]
},
"lodging": {
"price": "$45",
"address": {
"street": "323 Polar Street",
"city": "Lutsen",
"state": "Louisiana",
"coordinates": [
30.447311,
24.791852
]
},
"amenities": {
"freeWifi": true,
"parking": true,
"petsAllowed": true,
"elevator": true,
"balcony": true
},
"reviews": [
{
"reviewer": "Mariana Ayers",
"date": "2014-04-13T08:30:02 -02:00",
"cleanliness": 9,
"location": 6,
"food": 4
},
{
"reviewer": "Cole Simmons",
"date": "2015-05-07T06:00:09 -02:00",
"cleanliness": 1,
"location": 3,
"food": 2
}
]
}
},
{
"_id": "5bf31f8c8af00ea536cb92d7",
"index": 2,
"guid": "74ef5317-4949-4259-836c-43cc05eed32c",
"isActive": true,
"registered": "2010-09-12T02:38:43 -02:00",
"host": {
"name": "Nicholson",
"surname": "Cooper",
"gender": "male",
"age": 71,
"picture": "https://api.adorable.io/avatars/285/NicholsonCooper.png",
"languages": [
"german",
"english"
],
"contact": {
"company": "COMTENT",
"email": "nicholsoncooper@comtent.com",
"phone": "+1 (934) 472-2934"
},
"reviews": [
{
"reviewer": "Corinne Barber",
"date": "2017-01-22T08:16:59 -01:00",
"helpful": 9,
"kind": 6,
"responsive": 3
},
{
"reviewer": "Callahan Mann",
"date": "2015-08-18T03:46:07 -02:00",
"helpful": 9,
"kind": 5,
"responsive": 9
},
{
"reviewer": "Alberta Chan",
"date": "2016-07-27T01:59:55 -02:00",
"helpful": 9,
"kind": 2,
"responsive": 1
},
{
"reviewer": "Hampton Horn",
"date": "2017-08-08T04:20:22 -02:00",
"helpful": 9,
"kind": 4,
"responsive": 2
},
{
"reviewer": "Castillo Farley",
"date": "2015-07-04T12:00:38 -02:00",
"helpful": 9,
"kind": 3,
"responsive": 6
},
{
"reviewer": "Imogene Henson",
"date": "2014-12-22T04:15:35 -01:00",
"helpful": 4,
"kind": 6,
"responsive": 10
}
]
},
"lodging": {
"price": "$91",
"address": {
"street": "979 Varet Street",
"city": "Allendale",
"state": "Illinois",
"coordinates": [
24.238092,
-51.522132
]
},
"amenities": {
"freeWifi": true,
"parking": true,
"petsAllowed": true,
"airConditioning": true,
"balcony": true
},
"reviews": []
}
},
{
.
.
.
我尝试过这样的事情，但是，我对 mongodb 很陌生。
db.lodging.aggregate(
[
{$project: {"substring": {$substr: ["lodging.price", 1,-1 ]}} }, // String to substring (number).
{$project: {intfield: {$toInt: substring}}}, // Integer from substring for order by.
{$project: {}} // TODO: Number of amenities.
{$sort: {intfield: -1, numamenities: -1}}
]
);
【问题讨论】：
-
到底为什么要将
price值存储为字符串？使用数值数据类型。同样适用于date- 使用Date对象而不是字符串。 -
@Wernfried Domscheit 这是一个课堂作业，我昨天向教授问了同样的问题，他告诉我这是为了使用一些 mongodb 函数。
-
什么是“一些 mongodb 函数”？
标签： javascript mongodb sorting aggregate