This is how data is in my mongodb database.
_id:ObjectId('5c38e514b88edd0ef236c3f7'),
rooms:[
{
info:{
name:'John',
age:'23'
}
},
{
info:{
name:'Mary',
age:'15'
}
}
]
Using aggregation framework, I want to match then 'name' field which is inside the info object of which is in the rooms array. How do I achieve this?
What I have tried so far:
Hotel.aggregate([
{$match: {
'_id':mongoose.Types.ObjectId(lodgeId),
'rooms.info.name':'John'}}
)]
This gives me ALL ROOMS instead of matching the one with name John.
How do I get only the matched row?
If you unwind the rooms array before the match:
Hotel.aggregate([
{$unwind: "$rooms"},
{$match: {
'_id':mongoose.Types.ObjectId(lodgeId),
'rooms.info.name':'John'}}
)]
You should get a document with only the rooms that have the name John.
Unwind turns an array field into a new document for each item in the array.
Related
I am using mongoDB and nodejs
I have 4 collections
collection 1 is teacher with fields teacher_id, teacher_name
collection 2 is subject with fieldssubject _id, subject_name
collection 3 is book with fields book_id, book_name
collection is student which have fields -- _id, student_name, teacher_id, subject_id, book_id
how can I fetch ids from 1, 2, 3 collections simultaneously and insert to corresponding id in collection
I have tried some which always ask for a matching field... is ther any function which returns data from collection even though no match field?
can someone please help
Well, in that case, you need to fetch all the documents from those collections. That will be a bit costly aggregation but I'm adding here in code:
Firstly, I'm grouping on null, to avoid to attach lookup value to every single document in teacher collection.
db.teacher.aggregate([
{
$group:{
"_id":null,
"root":{
$push:"$$ROOT"
}
}
},
{
$lookup:
{
from:"subject",
pipeline: [],
as: "subjectLookup"
}
},
{
$lookup:
{
from:"book",
pipeline: [],
as: "bookLookup"
}
},
{
$lookup:
{
from:"student",
pipeline: [],
as: "studentLookup"
}
}
]).pretty()
These lookups will give the array which contains all the documents from respective collections, you can limit the documents by adding $match stage in the pipeline of lookup stage.
Hope this will solve your problem :)
my document schema goes like this
_id: kkj33h2kjkjh32jk34
events: [
{
_id: k234j3lk4k2j3h4j3j4
},
{
_id: k234j3lk4k2j3h4j3j4
},
{
_id: k234j3lk4k2j3h4j3j4
}
]
here is my query, I have a list of _ids of the subdocuments of events field and I need to get all the matched subdocuments as the response from the event field I have tried to use $in and many but failed can anyone suggest me how to do this
tried this
subarr=['fh576hgfu658uyg7h','k234j3lk4k2j3h4j3j4']
model.findOne({
clgid: req.query.clgid,
'events._id': {$in:subarr}
},{"events.$":1});
but the problem with the above code is that it is fetching the first matching subdocument. but I need all the matching subdocuments.
suggest me the right way to do this query so that I get all the matched subdocuments that match from array
The issue of your query matching only the first subdocument is the use of {"events.$":1} in your projection.
I'm not sure what you are actually intending to do.
{"events.$":1} will limit to the first (sub)document matching your query, as per the documentation of the $ operator.
Maybe you're trying only to get the _id of the subdocuments and then, please try the following:
subarr=['fh576hgfu658uyg7h','k234j3lk4k2j3h4j3j4']
model.findOne({
clgid: req.query.clgid,
'events._id': {$in:subarr}
},{"events._id":1});
query to find all the elements in the array in mongoose dynamically
below is the object
var res1= {
"category":["travel","cafe"],
"amount":"300"
}
There could be more elements in the category but I want to create the query which automatically finds all the elements in the database just like forEach works
The $in operator should to the trick. $in will look for documents where the provided field matches any of the values in the array. the query would look like this:
Detail.find({
category: { $in: ["travel", "cafe"] },
amount: 300
})
assuming the filters are coming in dynamically on the request, and that req.body.categories is an array of desired categories:
Detail.find({
category: { $in: req.body.categories },
amount: req.body.amount
})
I'm having issues with mongoose queries.
I am trying to check if a object with an Id is in an array of objects.
So my query is like
db.getCollection('adunits').find(
{_id: ObjectId("5bd9bc1ca4efae39d0b5a58e")},
{$in : ["5bf510156c154934150ef006","5bf5309e6c154934150f00a6","5bd9b874a4efae39d0b5a58d","5bf52a876c154934150efe4a"]}
)
As you can see, my ObjectId("5bd9...") IS NOT in the array. But my query returns the document with ObjectId("5bd9...").
Isn't the $in operator supposed to check if the _id in parameter is IN the array?
I wish it could return me a "0 fetched documents" because the id passed isn't in the array.
Thanks in advance
Your query is not right.
You can either find by id like so:
db.getCollection('adunits')
.find({_id: ObjectId("5bd9bc1ca4efae39d0b5a58e")})
to get a single document or use $in operator like so
db.getCollection('adunits')
.find({_id: { $in: ["5bf510156c154934150ef006","5bf5309e6c154934150f00a6",...]})
which will return documents which have one of the ids provided in the array.
You query condition finds adunits where _id = ObjectId("5bd9bc1ca4efae39d0b5a58e"), it returns the value that matches given condition. While $in operator should applied on a filed. Are you trying to achieve some thing like, find the documents that matches ids in given array.if yes , change your code to following. Visit mongodb official https://docs.mongodb.com/manual/reference/operator/query/in/.
db.getCollection('adunits').find(
{ "_id":
{ $in:
[ "5bf510156c154934150ef006",
"5bf5309e6c154934150f00a6",
"5bd9b874a4efae39d0b5a58d",
"5bf52a876c154934150efe4a"
]
}
});
Here's the sample document I'm trying to query
{
"_id":"asdf0-002f-42d6-b111-ade91df09249",
"user":[
{
"_id":"14bfgdsfg0-3708-46ee-8164-7ee1d029a507",
"n":"aaa"
},
{
"_id":"aasdfa89-5cfe-4861-8a9a-f77428158ca9",
"n":"bbb"
}
]
}
The document has 2 user references and contains the user _id and other misc information. I have the 2 user ids and am trying to get this document via only the user ids. I also don't know the order of the 2 ids. Is this a possible query?
col.findOne({
user:{
$all:[
{
_id:"14bfgdsfg0-3708-46ee-8164-7ee1d029a507"
},
{
_id:"aasdfa89-5cfe-4861-8a9a-f77428158ca9"
}
]
}
})
^^ Something that I've tried that doesn't work.
You are close with your $all attempt.
col.findOne({
"user._id":{
$all : [ "14bfgdsfg0-3708-46ee-8164-7ee1d029a507",
"aasdfa89-5cfe-4861-8a9a-f77428158ca9" ]
}
}
You can query a sub-document by wrapping it quotes. From there $all works against the values you are looking for.
Mongodb find a document with all subdocuments satisfying a condition shows a variation on this type of query.
ElemMatch should do the trick.
col.findOne({user:{$elemMatch:{"_id":"14bfgdsfg0-3708-46ee-8164-7ee1d029a507", "_id":"aasdfa89-5cfe-4861-8a9a-f77428158ca9" }}})