I have a collection "Owners" and I want to return a list of "Owner" matching a filter (any filter), plus the count of "Pet" from the "Pets" collection for that owner, except I don't want the dead pets. (made up example)
I need the returned documents to look exactly like an "Owner" document with the addition of the "petCount" field because I'm using Java Pojos with the Mongo Java driver.
I'm using AWS DocumentDB that does not support $lookup with filters yet. If it did I would use this and I'd be done:
db.Owners.aggregate( [
{ $match: {_id: UUID("b13e733d-2686-4266-a686-d3dae6501887")} },
{ $lookup: { from: 'Pets', as: 'pets', 'let': { ownerId: '$_id' }, pipeline: [ { $match: { $expr: { $ne: ['$state', 'DEAD'] } } } ] } },
{ $addFields: { petCount: { $size: '$pets' } } },
{ $project: { pets: 0 } }
]).pretty()
But since it doesn't this is what I got so far:
db.Owners.aggregate( [
{ $match: {_id: { $in: [ UUID("cbb921f6-50f8-4b0c-833f-934998e5fbff") ] } } },
{ $lookup: { from: 'Pets', localField: '_id', foreignField: 'ownerId', as: 'pets' } },
{ $unwind: { path: '$pets', preserveNullAndEmptyArrays: true } },
{ $match: { 'pets.state': { $ne: 'DEAD' } } },
{ "$group": {
"_id": "$_id",
"doc": { "$first": "$$ROOT" },
"pets": { "$push": "$pets" }
}
},
{ $addFields: { "doc.petCount": { $size: '$pets' } } },
{ $replaceRoot: { "newRoot": "$doc" } },
{ $project: { pets: 0 } }
]).pretty()
This works perfectly, except if an Owner only has "DEAD" pets, then the owner doesn't get returned because all the "document copies" got filtered out by the $match. I'd need the parent document to be returned with petCount = 0 when ALL of them are "DEAD". I cannot figure out how to do this.
Any ideas?
These are the supported operations for DocDB 4.0 https://docs.amazonaws.cn/en_us/documentdb/latest/developerguide/mongo-apis.html
EDIT: update to use $filter as $reduce not supported by aws document DB
You can use $filter to keep only not DEAD pets in the lookup array, then count the size of the remaining array.
Here is the Mongo playground for your reference.
$reduce version
You can use $reduce in your aggregation pipeline to to a conditional sum for the state.
Here is Mongo playground for your reference.
As of January 2022, Amazon DocumentDB added support for $reduce, the solution posted above should work for you.
Reference.
Related
I am using the following query:
query myOrgRepos {
organization(login: "COMPANY_NAME") {
repositories(first: 100) {
edges {
node {
name
defaultBranchRef {
target {
... on Commit {
history(after: "2021-01-01T23:59:00Z", before: "2023-02-06T23:59:00Z", author: { emails: "USER_EMAIL" }) {
edges {
node {
oid
}
}
}
}
}
}
}
}
}
}
}
But with accurate names for the orginization and emails, and am persistantly getting the following error for every repo.
{
"type": "INVALID_CURSOR_ARGUMENTS",
"path": [
"organization",
"repositories",
"edges",
20,
"node",
"defaultBranchRef",
"target",
"history"
],
"locations": [
{
"line": 10,
"column": 29
}
],
"message": "`2021-01-01T23:59:00Z` does not appear to be a valid cursor."
},
If I remove the after field, it works just fine. However, I kind of need it. Acording to all the docs that I have read both after and before take the same timestamp. Can't tell where I am going wrong here.
I have tried:
to narrow the gap between before and after
return only a single repository
remove after (works fine without it)
the mongodb data like this:
{
"_id": "123dsadasfa454sdsaw",
"hashmap": {
"uuid-12sadsadw5": {
"name": "bob"
},
"uuid-12sadsadwew5": {
"name": "alice"
}
},
"age": 10
}
"hashmap" like java HashMap, the key is uuid like "uuid-12sadsadwew5" and the value is object.
I want to get the data which the name in "hashmap" value is not null. And I use sql :
db.tabl1.find({"hashmap.values.name":{$ne:null}})
but cannot get the right result
You can use this aggregation query:
First use $objectToArray to create an array with values k and v. As we don't know the key (k) we can search by value (v).
Then $unwind array
And $match values where name is not null.
And then regroup and recreate the object using $arrayToObject.
db.collection.aggregate([
{
"$set": {
"hashmap": {
"$objectToArray": "$hashmap"
}
}
},
{
"$unwind": "$hashmap"
},
{
"$match": {
"hashmap.v.name": {
"$ne": null
}
}
},
{
"$group": {
"_id": "$_id",
"hashmap": {
"$push": "$hashmap"
}
}
},
{
"$set": {
"hashmap": {
"$arrayToObject": "$hashmap"
}
}
}
])
Example here
I'm a newbie on MongoDB. And I need help. I have a small project with SQLite (7 tables and 1 view). And I need to make this project on MongoDB, I'm using Studio 3T, I'm already migrate SQLite tables to MongoDB collections, but now I need to make (VIEW/TEST) for test this project. Please help how to write this SQL script with MongoDB.
SQLITE:
MongoDB:
SQLIte script I want to make with MongoDB:
CREATE VIEW rezultatas AS
SELECT p.pavadinimas AS detales_pavadinimas,
SUM(d.pagamintas_kiekis) AS pagamintas_kiekis,
SUM(z.gamybos_islaidos) AS vidutine_kaina,
STRFTIME('%m', d.pagaminimo_data) AS menuo,
STRFTIME('%Y', d.pagaminimo_data) AS metai
FROM detales d,
zinynas z,
produktas p
WHERE (z.detale_id = p._id_) AND
(d.detale_id = z.detale_id) AND
(d.pagaminimo_data >= z.data_nuo) AND
NOT EXISTS (
SELECT *
FROM zinynas
WHERE (d.detale_id = detale_id) AND
(d.pagaminimo_data >= data_nuo) AND
(z.data_nuo < data_nuo)
)
GROUP BY p.pavadinimas,
STRFTIME('%m', d.pagaminimo_data),
STRFTIME('%Y', d.pagaminimo_data)
I had to guess some things due to the lack of schemes but the basic layout should work.
We're going to use $createView with these parameters as input:
db.createView('rezultatas', 'produktas', pipeline)
Meaning our pipeline creating the view starts with the produktas collection.
The pipeline to use:
[
{ // match the documents from the zinyas collection.
$lookup:
{
from: "zinynas",
let: { produktas_id: "$_id" }, // i'm guessing its _id
pipeline: [
{ $match:
{ $expr: { $eq: [ "$detale_id", "$$produktas_id" ] }}
},
],
as: "z"
}
},
{
$unwind: "$z"
},
{ // match the documents from the detales collection. only keep the one with maximum data_nuo value.
$lookup:
{
from: "detales",
let: { z_detale_id: "$z.detale_id", z_data_nuo: "$z.data_nuo" },
pipeline: [
{ $match:
{
$and: [
{ $expr: { $eq: [ "$detale_id", "$$z_detale_id" ] }},
{ $expr: { $gte: [ "$pagaminimo_data", "$$z_data_nuo"]}}
]
}
},
{
$sort: {
data_nuo: -1
}
},
{
$limit: 1
}
],
as: "d"
}
},
{
$unwind: "$d"
},
{ // end up saving the fields we want.
$group: {
_id: { pavadinimas : "$pavadinimas", month: {$month: "$d.pagaminimo_data"}, year: {$year: "$d.pagaminimo_data"}},
pagamintas_kiekis: {$sum: "$d.pagamintas_kiekis"},
vidutine_kaina: {$sum: "$z.gamybos_islaidos"},
month: {$first: {$month: "$d.pagaminimo_data"}},
year: {$first: {$year: "$d.pagaminimo_data"}},
detales_pavadinimas: {$first: "$pavadinimas"}
}
}
]
I have a mongodb query: (Give me the settings where account='test')
db.collection_name.find({"account" : "test1"}, {settings : 1}).pretty();
where I get the following sample output:
{
"_id" : ObjectId("49830ede4bz08bc0b495f123"),
"settings" : {
"clusterData" : {
"us-south-1" : "cluster1",
"us-east-1" : "cluster2"
},
},
What I'm looking for now, is to give me the account where the clusterData has more than 1 key.
I'm only interested in listing those accounts with (2) or more keys.
I've tried this: (but this doesn't work)
db.collection_name.find({'settings.clusterData.1': {$exists: true}}, {account : 1}).pretty();
Is this possible to do with the current data structure? I don't have the option to redesign this schema.
Your clusterData field is not an array which is why you cannot just filter the number of elements it has. There is a way, though, to get what you want via the aggregation framework. Try this:
db.collection_name.aggregate({
$match: {
"account" : "test1"
}
}, {
$project: {
"settingsAsArraySize": { $size: { $objectToArray: "$settings.clusterData" } },
"settings.clusterData": 1
}
}, {
$match: {
"settingsAsArraySize": { $gt: 1 }
}
}, {
$project: {
"_id": 0,
"settings.clusterData": 1
}
}).pretty();
I have this query that provides me the join I want to:
db.summoners.aggregate([
{ "$match": { "nick":"Luispfj" } },
{ "$unwind": "$matches" },
{
"$lookup": {
"from":"matches",
"localField":"matches.gameId",
"foreignField":"gameId",
"as":"fullMatches"
}
},
{ "$unwind": "$fullMatches" },
{
"$group": {
"_id": null,
"matches": { "$push":"$fullMatches" }
}
}
])
But when I run the unwind function the null entries are gone. How do I retrieve them (with their respective "gameId"s, if possible?
Also, is there a way to retrieve only the matches array, instead of it being a subproperty of the "null-id-object" it creates?
$unwind takes an optional field preserveNullAndEmptyArrays which by default is false. If you set it to true, unwind will output the documents that are null. Read more about $unwind
{
"$unwind": {
path: "$fullMatches",
preserveNullAndEmptyArrays: true
}
},