im having trouble query this type of data
[
{ev:1,
image:[{id:24,name:'ads1'},{id:25,name:'ads2'},{id:26,name:'ads4'},{id:27,name:'ads3'}]
},
{ev:1,
image:[{id:29,name:'ads1'},{id:23,name:'ads2'},{id:34,name:'ads4'},{id:50,name:'ads3'}]
}
]
this is my query
var data = schema.find( {
$and: [
{
ev: 1
},
{
'image.id': {
$in: [26,29,50,34]
}
}
]
} , 'ev image' )
what result i need is
[
{ev:1,
image:[{id:26,name:'ads4'}]
},
{ev:1,
image:[{id:29,name:'ads1'},{id:34,name:'ads4'}, {id:50,name:'ads3'}]
}
]
Im using moongose
but i keep getting back the whole image array
i basically need the image object filtered with only the image.id i want
PS there are more ev 1,2,3.... hence i need to only find in the ev i provide
could someone please help me with this
im new to mongodb
Find is used to keep or reject complete documents(find has a project also but in general for transformations we use aggregate operators).
The bellow is aggregation that keeps only part of the array.
Query
match the ev=1
filter the image and keep only those that are contained in the the array [26, 29, 50, 34]
if you want you can add another match to filter out the documents with empty array (no id was member of the array)
PlayMongo
aggregate(
[{"$match": {"ev": {"$eq": 1}}},
{"$set":
{"image":
{"$filter":
{"input": "$image",
"cond": {"$in": ["$$this.id", [26, 29, 50, 34]]}}}}}])
Related
here is the document
formId: 123,
title:"XYZ"
eventDate:"2022-04-15T05:40:57.182Z"
responses:[
{
orderId:98422,
name:"XYZ1",
email:"a#gmal.com",
paymentStatus:"pending",
amount:250,
phone:123456789
},
{
orderId:98422,
name:"XYZ1",
email:"a#gmal.com",
paymentStatus:"success",
amount:250,
phone:123456791
}
]
I used $elemMatch to filter the array such that I get only the matched object.
const response = await Form.findOne({ formId:123 }, {
_id:0,
title: 1,
eventDate: 1,
responses: {
$elemMatch: { orderId: 98422 },
},
})
But this returns all the fields inside the object present in the array "responses".
title:"XYZ"
eventDate:"2022-04-15T05:40:57.182Z"
responses:[
{
orderId:98422,
name:"XYZ1",
email:"a#gmal.com",
paymentStatus:"pending",
amount:250,
phone:123456789
}
]
But I want only specific fields to be returned inside the object like this
title:"XYZ"
eventDate:"2022-04-15T05:40:57.182Z"
responses:[
{
name:"XYZ1",
email:"a#gmal.com",
paymentStatus:"pending",
}
]
How can i do that ?
Query
aggregation way to keep some members and edit them also
map on responses if orderId matches keep the fields you want, the others are replaced with null
filter to remove those nulls (members that didnt match)
here 2 matches if you want to keep only one member of the array you can use
[($first ($filter ...)]
*$elemMatch that you used can be combined with the $ project operator to avoid the aggregation, but with $ operator we get all the matching member (here you want only some fields so i think aggregation is the way)
Playmongo
aggregate(
[{"$match": {"formId": {"$eq": 123}}},
{"$project":
{"_id": 0,
"title": 1,
"eventDate": 1,
"responses":
{"$map":
{"input": "$responses",
"in":
{"$cond":
[{"$eq": ["$$this.orderId", 98422]},
{"name": "$$this.name",
"email": "$$this.email",
"paymentStatus": "$$this.paymentStatus"},
null]}}}}},
{"$set":
{"responses":
{"$filter":
{"input": "$responses", "cond": {"$ne": ["$$this", null]}}}}}])
I have a group collection that has the array order that contains ids.
I would like to use updateOne to set multiple items in that order array.
I tried this which updates one value in the array:
db.groups.updateOne({
_id: '831e0572-0f04-4d84-b1cf-64ffa9a12199'
},
{$set: {'order.0': 'b6386841-2ff7-4d90-af5d-7499dd49ca4b'}}
)
That correctly updates (or sets) the array value with index 0.
However, I want to set more array values and updateOne also supports a pipeline so I tried this:
db.slides.updateOne({
_id: '831e0572-0f04-4d84-b1cf-64ffa9a12199'
},
[
{$set: {'order.0': 'b6386841-2ff7-4d90-af5d-7499dd49ca4b1'}}
]
)
This does NOTHING if the order array is empty. But if it's not, it replaces every element in the order array with an object { 0: 'b6386841-2ff7-4d90-af5d-7499dd49ca4b1' }.
I don't understand that behavior.
In the optimal case I would just do
db.slides.updateOne({
_id: '831e0572-0f04-4d84-b1cf-64ffa9a12199'
},
[
{$set: {'order.0': 'b6386841-2ff7-4d90-af5d-7499dd49ca4b1'}},
{$set: {'order.1': 'otherid'}},
{$set: {'order.2': 'anotherone'}},
]
)
And that would just update the order array with the values.
What is happening here and how can I achieve my desired behavior?
The update by index position in the array is only supported in regular update queries, but not in aggregation queries,
They have explained this feature in regular update query $set operator documentation, but not it aggregation $set.
The correct implementation in regular update query:
db.slides.updateOne({
_id: '831e0572-0f04-4d84-b1cf-64ffa9a12199'
},
{
$set: {
'order.0': 'b6386841-2ff7-4d90-af5d-7499dd49ca4b1',
'order.1': 'otherid',
'order.2': 'anotherone'
}
}
)
If you are looking for only an aggregation query, it is totally long process than the above regular update query, i don't recommend that way instead, you can format your input in your client-side language and use regular query.
If you have to use aggregation framework, try this (you will have to pass array of indexes and array of updated values separately):
$map and $range to iterate over the order array by indexes
$cond and $arrayElemAt to check if the current index is in the array of indexes that has to be updates. If it is, update it with the same index from the array of new values. If it is not, keep the current value.
NOTE: This will work only if the array of indexes that you want to update starts from 0 and goes up (as in your example).
db.collection.update({
_id: '831e0572-0f04-4d84-b1cf-64ffa9a12199'
},
[
{
"$set": {
"order": {
"$map": {
input: {
$range: [
0,
{
$size: "$order"
}
]
},
in: {
$cond: [
{
$in: [
"$$this",
[
0,
1,
2
]
]
},
{
$arrayElemAt: [
[
"b6386841-2ff7-4d90-af5d-7499dd49ca4b1",
"otherid",
"anotherone"
],
"$$this"
]
},
{
$arrayElemAt: [
"$order",
"$$this"
]
}
]
}
}
}
}
}
])
Here is the working example: https://mongoplayground.net/p/P4irM9Ouyza
Is there a direct way to project a new field if a value matches one in a huge sub array. I know i can use the $elemMatch or $ in the $match condition, but that would not allow me to get the rest of the non matching values (users in my case).
Basically i want to list all type 1 items and show all the users while highlighting the subscribed user. The reason i want to do this through mongodb is to avoid iterating over multiple thousand users for every item. Infact that is the part 2 of my question, can i limit the number of user's array that would be returned, i just need around 10 array values to be returned not thousands.
The collection structure is
{
name: "Coke",
type: 2,
users:[{user: 13, type:1},{ user:2: type:2}]
},
{
name: "Adidas",
type: 1,
users:[{user:31, type:3},{user: 51, type:1}]
},
{
name: "Nike",
type: 1,
users:[{user:21, type:3},{user: 31, type:1}]
}
Total documents are 200,000+ and growing...
Every document has 10,000~50,000 users..
expected return
{
isUser: true,
name: "Adidas",
type: 1,
users:[{user:31, type:3},{user: 51, type:1}]
},
{
isUser: false,
name: "Nike",
type: 1,
users:[{user:21, type:3},{user: 31, type:1}]
}
and i've been trying this
.aggregate([
{$match:{type:1}},
{$project:
{
isUser:{$elemMatch:["users.user",51]},
users: 1,
type:1,
name: 1
}
}
])
this fails, i get an error "Maximum Stack size exceeded". Ive tried alot of combinations and none seem to work. I really want to avoid running multiple calls to mongodb. Can this be done in a single call?
I've been told to use unwind, but i am bit worried that it might lead to memory issues.
If i was using mysql, a simple subquery would have done the job... i hope i am overlooking a similar simple solution in mongodb.
Process the conditions for the array elements and match the result by using a combination of the $anyElementTrue which evaluates an array as a set and returns true if any of the elements are true and false otherwise, the $ifNull operator will act as a safety net that evaluates the following $map expression and returns the value of the expression if the expression evaluates to a non-null value. The $map in the $ifNull operator is meant to apply the conditional statement expression to each item in the users array and returns an array with the applied results. The resulting array will then be used evaluated by the $anyElementTrue and this will ultimately calculate and return the isUser field for each document:
db.collection.aggregate([
{ "$match": { "type": 1} },
{
"$project": {
"name": 1, "type": 1,
"isUser": {
"$anyElementTrue": [
{
'$ifNull': [
{
"$map": {
"input": "$users",
"as": "el",
"in": { "$eq": [ "$$el.user",51] }
}
},
[false]
]
}
]
}
}
}
])
I am using MongoDB and Node.js to display a record set in a page. I have got as far as displaying them on the page alphabetically, but I would like to display one row (the "default" row) at the top, and all the others alphabetically beneath it.
I know, I know, Mongo is definitely not SQL, but in SQL I would have done something like this:
SELECT *
FROM themes
ORDER BY name != "Default", name ASC;
or perhaps even
SELECT * FROM themes WHERE name = "Default"
UNION
SELECT * FROM themes WHERE name != "Default" ORDER BY name ASC;
I have tried a few variations of Mongo's sorting options, such as
"$orderby": {'name': {'$eq': 'Default'}, 'name': 1}}
but without any luck so far. I have been searching a lot for approaches to this problem but I haven't found anything. I am new to Mongo but perhaps I'm going about this all wrong.
My basic code at the moment:
var db = req.db;
var collection = db.get('themes');
collection.find({"$query": {}, "$orderby": {'name': 1}}, function(e, results) {
res.render('themes-saved', {
title: 'Themes',
section: 'themes',
page: 'saved',
themes: results
});
});
You cannot do that in MongoDB, as sorting must be on a specific value already present in a field of your document. What you "can" do is $project a "weighting" to the record(s) matching your condition. As in:
collection.aggregate(
[
{ "$project": {
"each": 1,
"field": 1,
"youWant": 1,
"name": 1,
"weight": {
"$cond": [
{ "$eq": [ "$name", "Default" ] },
10,
0
]
}
}},
{ "$sort": { "weight": -1, "name": 1 } }
],
function(err,results) {
}
);
So you logically inspect the field you want to match a value in ( or other logic ) and then assign a value to that field, and a lower score or 0 to those that do not match.
When you then $sort on that "weighting" first in order ( decending from highest in this case ) so that those values are listed before others with a lower weighting.
I want to run a query to select specific documents. Then on each document, open up an array of sub documents and run a query to filter those sub docs.
Example:
{
"_id" : ObjectID(23412351346435),
"list" : [
{date: ISODate(2015-01-12T00:00:00.000Z), name: "Jan 12"},
{date: ISODate(2015-01-13T00:00:00.000Z), name: "Jan 13"},
{date: ISODate(2015-01-14T00:00:00.000Z), name: "Jan 14"}
]
}
I'm guessing I can do something with Mongo's aggregate function. I have been able to match the documents I want, but how can I get a sub query going on the array? I tried using $elemMatch but that only returns the first item in the array that matches the date range.
To be clear when I query for ObjectID(23412351346435) and Date range 2015-01-12 to 2015-01-13 I want it to return this;
{
"_id" : ObjectID(23412351346435),
"list" : [
{date: ISODate(2015-01-12T00:00:00.000Z), name: "Jan 12"},
{date: ISODate(2015-01-13T00:00:00.000Z), name: "Jan 13"}
]
}
As you guessed, you can use aggregation to get the results you are looking for. The steps you need in your aggregation pipeline are the following.
Match the documents you want. (I've done that here by _id).
Unwind the list array.
Match the dates you are looking for using a range query.
Group the documents back by _id.
Your query should look something like this:
db.collection.aggregate([
{ "$match": { "_id": ObjectId("54ef8b0acfb269d664de0b48")} },
{ "$unwind": "$list" },
{ "$match": {
"list.date": { $gte: ISODate("2015-01-12T00:00:00.000Z"),
$lte: ISODate("2015-01-13T00:00:00.000Z")
}
}},
{ "$group": {
"_id": "$_id",
"list": { "$push": { "date": "$list.date", "name": "$list.name" }}
}}
]);
You can use the $unwind operator. It allows you to take an array in a document, and clone that document with each of the array elements. Then you can match on the field. If necessary, you can use $group to wind the document back up.
[
{$match:{...}},
{$unwind:"myfield"},
{$match:{"myfield.name":"Jan 12"}},
{$group:{ _id:"$id", "myfield":{$push:"$myfield"} }}
]
Note that $unwind is slow for large sets of documents, and combinatoric for multiple arrays. It is the only option you really have for Mongo 2.4.x though. You might be better served by rearranging your data so that you do not have arrays.