Mongodb - group by value and get count - mongodb

Question

I have a aggregate query , which returns result like
{
count:1,
status: 'FAILED',
article_id: 1
},
{
count:1,
status: 'DELIVERED',
article_id: 1
}
I want to group by on the article_id and get the count based on the status , something like this:
{
article_id:1,
FAILED:1,
DELIVERED:2
}
How can i archive this?
Thanks in advance.

Answer 1

The other answers may work in principle, however they are limited hard-coded to status FAILED and DELIVERED.
In case you like to have a generic solution for arbitrary status, you can use this one:
db.collection.aggregate([
{ $set: { data: [{ k: "$status", v: "$count" }] } },
{
$replaceRoot: {
newRoot: {
$mergeObjects: [
{ $arrayToObject: "$data" }, { article_id: "$article_id" }
]
}
}
},
{
$group: {
_id: "$article_id",
status: { $push: "$$ROOT" }
}
},
{ $set: { status: { $mergeObjects: ["$status"] } } },
{ $replaceRoot: { newRoot: "$status" } },
])
Mongo playground

Answer 2

Try this code
db.getCollection('artwork').aggregate([
{
$group: {
_id: '$article_id',
FAILED: {
'$sum': {
"$cond": [{ "$eq": ["$status", "FAILED"] }, 1, 0]
}
},
DELIVERED: {
'$sum': {
"$cond": [{ "$eq": ["$status", "DELIVERED"] }, 1, 0]
}
}
}
}
])
mongoplayground

Answer 3

{
$group:{
_id:"$_id",
articleId:{$addToset:"$article_id"},
failed:{$addToset:"$failed"},
delivered:{$addToset:"$delivered"}
}
},
{ $addFields:{
article_id:{$size:articleId},
fail:{$size:"$faild"},
deliver:{$size:"$faild"},
}
In group $addToSet will return array and in addField will return total length of array. you cans earch $size in mongo
}