Aggregate by all days of month mongodb - mongodb

Question

Hey i need to get the sum of all totalPrice group by days
I get this result
but i need to fetch all rest days of month even if it returns 0
i need solution
this is my code
Order.aggregate([
{ $project: { yearMonthDay: { $dateToString: { format: "%Y-%m-%d", date: '$created' }}, totalPrice:"$totalPrice" }},
{ $group: { _id: "$yearMonthDay", count: { $sum: 1 }, total: {"$sum": "$totalPrice"} }},
{ $sort: { _id: -1 } },
{ $group: { _id: null, stats: { $push: "$$ROOT" }}},
{
$project: {
results: {
$map: {
input:{ $range:[16,31] },
as: 'day',
in: {
$let: {
vars: {
dateIndex: {
"$indexOfArray": ["$stats._id", {$dateToString:{ date:{$dateFromParts:{'year':2020, 'month':5, 'day':"$$day"}}, format:'%Y-%m-%d'}}]
}
},
in: {
$cond: {
if: { $ne: ["$$dateIndex", -1] },
then: { $arrayElemAt: ["$stats", "$$dateIndex"] },
else: { _id: {$dateToString:{ date:{$dateFromParts:{'year':2020, 'month':5, 'day':"$$day"}}, format:'%Y-%m-%d'}, count: 0, total: 0 } }
}
}
}
}
}
}
}
},
{ $unwind: "$results" },
{ $replaceRoot: { newRoot: "$results"}}
]

Answer 1

This query should work for you.
db.collectionName.aggregate([
{ $project: { yearMonthDay: { $dateToString: { format: "%Y-%m-%d", date: '$created' }}, totalPrice:"$totalPrice" }},
{ $group: { _id: "$yearMonthDay", count: { $sum: 1 }, total: {"$sum": "$totalPrice"} }},
{ $sort: { _id: -1 } },
{ $group: { _id: null, stats: { $push: "$$ROOT" }},
{
$project: {
results: {
$map: {
input: ["2020-05-16","2020-05-15","2020-05-14","2020-05-13","2020-05-12"],
as: "date",
in: {
$let: {
vars: {
dateIndex: {
"$indexOfArray": ["$stats._id", "$$date"]
}
},
in: {
$cond: {
if: { $ne: ["$$dateIndex", -1] },
then: { $arrayElemAt: ["$stats", "$$dateIndex"] },
else: { _id: "$$date", count: 0, total: 0 }
}
}
}
}
}
}
}
},
{ $unwind: "$results" },
{ $replaceRoot: { newRoot: "$results"}}
])
The First 3 steps is same as yours.
{ $group: { _id: null, stats: { $push: "$$ROOT" }} will push previous stage results into an arrray stats which we will use for lookup in later stage.
In last stage, we will create possible date range and iterate over that.
for each key in range.
"$indexOfArray": ["$stats._id", "$$date"] will check if date is present in stats array or not
Then we will use that index to fetch value from stats array otherwise push default values.
As these results are still under results, we will unwind that array and move to root.
If you server version is above 3.6,
we can simplify date range creation part as well. let's initialize input arrays as days using $range.
input:{ $range:[16,31] },
as: 'day'
and modifiy dateIndex part like this
dateIndex: {
"$indexOfArray": ["$stats._id", {$dateToString:{ date:{$dateFromParts:{'year':2020, 'month':5, 'day':"$$day"}}, format:'%Y-%m-%d'}]
}
And change default value part as well similarly.
else: { _id: {$dateToString:{ date:{$dateFromParts:{'year':2020, 'month':5, 'day':"$$day"}}, format:'%Y-%m-%d'}}, count: 0, total: 0 }
Or alternatively, we can also use concat for generating keys
dateIndex: {
"$indexOfArray": ["$stats._id", {$concat:["2020-05","-", {$convert:{input:"$$day", to:"string"}}]}]
}
// And default value
else: { _id: {$concat:["2020-05","-", {$convert:{input:"$$day", to:"string"}}]}, count: 0, total: 0 }
Similarly, you can run another loop for months as well.