我如何使用 Mongo 功能对这些数据进行排序:
输入
{ "_id" : 1, "domainName" : "test1.com", "hosting" : "hostgator.com" }
{ "_id" : 2, "domainName" : "test2.com", "hosting" : "aws.amazon.com"}
{ "_id" : 3, "domainName" : "test3.com", "hosting" : "aws.amazon.com" }
{ "_id" : 4, "domainName" : "test4.com", "hosting" : "hostgator.com" }
{ "_id" : 5, "domainName" : "test5.com", "hosting" : "aws.amazon.com" }
{ "_id" : 6, "domainName" : "test6.com", "hosting" : "cloud.google.com" }
{ "_id" : 7, "domainName" : "test7.com", "hosting" : "aws.amazon.com" }
{ "_id" : 8, "domainName" : "test8.com", "hosting" : "hostgator.com" }
{ "_id" : 9, "domainName" : "test9.com", "hosting" : "cloud.google.com" }
{ "_id" : 10, "domainName" : "test10.com", "hosting" : "godaddy.com" }
按照托管字段的顺序,获取结果,例如按以下顺序:
1)首先 - 所有的godaddy;
2) 其次——所有 AWS;
3)接下来,其他一切。
输出
{
"result" : [
{
"_id" : 10,
"domainName" : "test10.com",
"hosting" : "godaddy.com"
},
{
"_id" : 2,
"domainName" : "test2.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 3,
"domainName" : "test3.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 5,
"domainName" : "test5.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 7,
"domainName" : "test7.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 1,
"domainName" : "test1.com",
"hosting" : "hostgator.com"
},
{
"_id" : 4,
"domainName" : "test4.com",
"hosting" : "hostgator.com"
},
{
"_id" : 6,
"domainName" : "test6.com",
"hosting" : "cloud.google.com"
},
{
"_id" : 8,
"domainName" : "test8.com",
"hosting" : "hostgator.com"
},
{
"_id" : 9,
"domainName" : "test9.com",
"hosting" : "cloud.google.com"
},
]
}
在这个例子中,我想以更相关的方式为用户返回结果。在原始任务中,我想使用其他一些提供附加信息的集合对其进行排序。
但是如果你帮助我完成以前的任务就足够了吗?
UPD: 关于问题的第二部分。
另一项任务是如何从一个集合中返回可排序的数据,并依赖于另一个集合。
例子:
第一个集合与之前给出的相同:
{ "_id" : 1, "domainName" : "test1.com", "hosting" : "hostgator.com" }
...
第二个集合,提供一些关于托管的额外信息:
{ '_id': 123, 'quality':'best', 'hostings': ["hostgator.com", "aws.amazon.com"]},
{ '_id': 321, 'quality':'good', 'hostings': ["cloud.google.com"]},
{ '_id': 345, 'quality':'bad', 'hostings': ["godaddy.com"]},
结果,我需要按以下顺序从第一个收集数据返回:
1)首先所有好的主机
2)其次一切都好
3)第三个都不好
输出:
{
"result" : [
//Best:
{
"_id" : 1,
"domainName" : "test1.com",
"hosting" : "hostgator.com"
},
{
"_id" : 4,
"domainName" : "test4.com",
"hosting" : "hostgator.com"
},
{
"_id" : 8,
"domainName" : "test8.com",
"hosting" : "hostgator.com"
},
{
"_id" : 2,
"domainName" : "test2.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 3,
"domainName" : "test3.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 5,
"domainName" : "test5.com",
"hosting" : "aws.amazon.com"
},
{
"_id" : 7,
"domainName" : "test7.com",
"hosting" : "aws.amazon.com"
},
// Good:
{
"_id" : 9,
"domainName" : "test9.com",
"hosting" : "cloud.google.com"
},
{
"_id" : 6,
"domainName" : "test6.com",
"hosting" : "cloud.google.com"
},
//Bad
{
"_id" : 10,
"domainName" : "test10.com",
"hosting" : "godaddy.com"
}
]
}
更新 2
我在前面的例子中得到了很好的答案和例子。非常感谢!但我举另一个例子。
我需要比较 3 个集合的 ID 以按顺序排序 - 第一个: friend ,第二个:“请求”,以及:其他用户。
输入
db.friends.find({userId: currentUser});
// {"_id" : "PgC7LrtaZtQsShtzT", "userId" : "tHuxnWxFLHvcpRgHb", "friendId" : "jZagPF7bd4aW8agXb",}
db.requests.find({userId: currentUser});
// looks like friend but with 'requesterId'
现在我需要聚合“用户”集合,定义与前两个集合( friend 、请求)匹配的分数。
使用提供的答案,我管理了结果,但只有一个集合。我怎样才能用 3 个或多个来做这个?
最佳答案
您可以将每个 hosting
投影到由整数表示的单独类型,最后对这些整数进行排序。在下面的聚合管道中说明
[
{$lookup: {
from: 'secondCollectionStoringQuality',
localField: 'hosting',
foreignField: 'hostings',
as: 'nw'
}},
{$unwind: '$nw'},
{$project: {
domainName: 1,
hosting: 1,
type: {
$cond: [
{$eq: ['$nw.quality', 'best']},
0,
{$cond: [
{$eq: ['$nw.quality', 'good']},
1,
2
]}
]
}
}},
{$sort: {type: 1}}
]
关于mongodb - 如何按自定义顺序对 Mongo 中的数据进行排序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40803878/