结构如下:
{
"_id" : "79f00e2f-5ff6-42e9-a341-3d50410168de",
"bookings" : [
{
"name" : "name1",
"email" : "george_bush@gov.us",
"startDate" : ISODate("2013-12-31T22:00:00Z"),
"endDate" : ISODate("2014-01-09T22:00:00Z")
},
{
"name" : "name2",
"email" : "george_bush@gov.us",
"startDate" : ISODate("2014-01-19T22:00:00Z"),
"endDate" : ISODate("2014-01-24T22:00:00Z")
}
],
"name" : "Hotel0",
"price" : 0,
"rating" : 2
}
现在,我想生成一份报告,告诉我预订了多少次,按预订月份分组(假设只有预订开始日期有关),并按酒店评级分组。
我希望答案是这样的:
{
{
rating: 0,
counts: {
month1: 10,
month2: 20,
...
month12: 7
}
}
{
rating: 1,
counts: {
month1: 5,
month2: 8,
...
month12: 9
}
}
...
{
rating: 6,
counts: {
month1: 22,
month2: 23,
...
month12: 24
}
}
}
我尝试使用聚合框架,但我有点卡住了。