问题
My collection looks like below with details
/* 1 createdAt:6/13/2018, 5:17:07 PM*/
{ "_id" : ObjectId("5b21043b18f3bc7c0be3414c"),
"Number" : 242,
"State" : "2",
"City" : "3",
"Website" : "",
"Contact_Person_Name" : "Ajithmullassery",
"CreatedById" : "Admin",
"UpdatedById" : "Admin",
"IsActive" : true,
"UpdatedOn" : ISODate("2018-06-13T17:17:07.313+05:30"),
"CreatedOn" : ISODate("2018-06-13T17:17:07.313+05:30")
},
/* 2 createdAt:6/13/2018, 6:45:42 PM*/
{
"_id" : ObjectId("5b2118fe18f3bc7c0be3415b"),
"Number" : 243,
"State" : "1",
"City" : "143",
"Website" : "",
"Contact_Person_Name" : "sachitkumar",
"CreatedById" : "vinoth",
"UpdatedById" : "Admin",
"IsActive" : true,
"UpdatedOn" : ISODate("2018-06-13T18:45:42.590+05:30"),
"CreatedOn" : ISODate("2018-06-13T18:45:42.590+05:30")
},
/* 3 createdAt:6/18/2018, 5:34:33 PM*/
{
"_id" : ObjectId("5b279fd118f3bc7c0be34166"),
"Number" : 244,
"State" : "0",
"City" : "8",
"Website" : "",
"Contact_Person_Name" : "Akshay",
"CreatedById" : "vinoth",
"UpdatedById" : "Admin",
"IsActive" : true,
"UpdatedOn" : ISODate("2018-06-18T17:34:33.270+05:30"),
"CreatedOn" : ISODate("2018-06-18T17:34:33.270+05:30")
},
/* 4 createdAt:6/20/2018, 1:02:21 PM*/
{
"_id" : ObjectId("5b2a030518f3bc7c0be3416d"),
"Number" : 245,
"State" : "5",
"City" : "6",
"Website" : "",
"Contact_Person_Name" : "Dr DS Mithra",
"CreatedById" : "vinoth",
"UpdatedById" : "Admin",
"FacilityID" : "594387f5e2de7be83be5d5f1",
"IsActive" : true,
"UpdatedOn" : ISODate("2018-06-20T13:02:21.887+05:30"),
"CreatedOn" : ISODate("2018-06-20T13:02:21.887+05:30")
},
/* 5 createdAt:6/20/2018, 1:08:58 PM*/
{
"_id" : ObjectId("5b2a049218f3bc7c0be3416e"),
"Number" : 245,
"State" : "5",
"City" : "6",
"Website" : "",
"Contact_Person_Name" : "Ramaswamy Manickam",
"CreatedById" : "vinoth",
"UpdatedById" : "Admin",
"IsActive" : true,
"UpdatedOn" : ISODate("2018-06-20T13:08:58.040+05:30"),
"CreatedOn" : ISODate("2018-06-20T13:08:58.040+05:30")
}
I have the query like below
db.collectionName.aggregate([
//where query
{ "$match": { $and:[{CreatedOn:{$lte:ISODate("2018-07-14T13:59:08.266+05:30")}},{CreatedOn:{$gte:ISODate("2018-06-10T13:59:08.266+05:30")}}] } },
//distinct column
{
"$group": {
_id: {$week: '$CreatedOn'},
documentCount: {$sum: 1}
}
}
])
The query will return the weeknumber and number of documents created as below
/* 1 */
{
"_id" : 26,
"documentCount" : 1
},
/* 2 */
{
"_id" : 25,
"documentCount" : 1
},
/* 3 */
{
"_id" : 24,
"documentCount" : 9
},
/* 4 */
{
"_id" : 23,
"documentCount" : 2
}
In above _id is the weeknumber. If in case in above results weekNumber : 23 no records are created then the query gives only 3 records removing the "_id":23.
How to get the records with documentcount as zero when there is no records created.
Like in above example when no records for _id: 23 should get like below
/* 4 */
{
"_id" : 23,
"documentCount" : 0
}
回答1:
As $week can return a value between 0 and 53 I assume you expect 54 documents as a result with 0 or non-zero values for documentCount. To achieve that you should collect all your documents into one ($group-ing by null) and then generate the output.
To generate a range of numbers you can use $range operator and then you can generate the output using $map. To transform an array of documents into multiple docs you can use $unwind.
db.collectionName.aggregate([
//where query
{ "$match": { $and:[{CreatedOn:{$lte:ISODate("2018-07-14T13:59:08.266+05:30")}},{CreatedOn:{$gte:ISODate("2018-06-10T13:59:08.266+05:30")}}] } },
//distinct column
{
"$group": {
_id: {$week: '$CreatedOn'},
documentCount: {$sum: 1}
}
},
{
$group: {
_id: null,
docs: { $push: "$$ROOT" }
}
},
{
$project: {
docs: {
$map: {
input: { $range: [ {$week:ISODate("2018-06-10T13:59:08.266+05:30")}, {$week:ISODate("2018-07-14T13:59:08.266+05:30")}]},
as: "weekNumber",
in: {
$let: {
vars: { index: { $indexOfArray: [ "$docs._id", "$$weekNumber" ] } },
in: {
$cond: {
if: { $eq: [ "$$index", -1 ] },
then: { _id: "$$weekNumber", documentCount: 0 },
else: { $arrayElemAt: [ "$docs", "$$index" ] }
}
}
}
}
}
}
}
},
{
$unwind: "$docs"
},
{
$replaceRoot: {
newRoot: "$docs"
}
}
])
Using $indexOfArray to check if array of current docs contains the document (-1 otherwise) and $arrayElemAt to get existing document from docs. Last step ($replaceRoot) is just to get rid of one level of nesting (docs). Outputs:
{ "_id" : 0, "documentCount" : 0 }
{ "_id" : 1, "documentCount" : 0 }
{ "_id" : 2, "documentCount" : 0 }
...
{ "_id" : 22, "documentCount" : 0 }
{ "_id" : 23, "documentCount" : 2 }
{ "_id" : 24, "documentCount" : 9 }
{ "_id" : 25, "documentCount" : 1 }
{ "_id" : 26, "documentCount" : 1 }
{ "_id" : 27, "documentCount" : 0 }
...
{ "_id" : 52, "documentCount" : 0 }
{ "_id" : 53, "documentCount" : 0 }
You can easily customize returned results modifying the input of $map stage. For instance you can pass an array of consts like input: [21, 22, 23, 24] as well.
EDIT: To get the weeks between specified dates you can use $week for start and end date to get the numbers.
来源：https://stackoverflow.com/questions/51474838/how-to-show-0-for-week-when-no-record-is-matching-that-week-in-week-mongodb-que