Consider I have this document in my MongoDB collection, Workout:
{
_id: ObjectId("60383b491e2a11272c845749") <--- Workout ID
user: ObjectId("5fc7d6b9bbd9473a24d3ab3e") <--- User ID
exercises: [
{
_id: ObjectId("...") <--- Exercise ID
exerciseName: "Bench Press",
sets: [
{
_id: ObjectId("...") <--- Set ID
},
{
_id: ObjectId("...") <--- Set ID
}
]
}
]
}
The Workout object can include many exercise objects in the exercises array and each exercise object can have many set objects in the sets array. I am trying to implement a delete functionality for a certain set. I need to retrieve the workout that the set I want to delete is stored in. I have access to the user's ID (stored in a context), exercise ID and the set ID that I want to delete as parameters for the .findOne() function. However, I'm not sure whether I can traverse through the different levels of arrays and objects within the workout object. This is what I have tried:
const user = checkAuth(context) // Gets logged in user details (id, username)
const exerciseID, setID // Both of these are passed in already and are set to the appropriate values
const workoutLog = Workout.findOne({
user: user.id,
exercises: { _id: exerciseID }
});
This returns an empty array but I am expecting the whole Workout object that contains the set that I want to delete. I would like to omit the exerciseID from this function's parameters and just use the setID but I'm not sure how to traverse through the array of objects to access it's value. Is this possible or should I be going about this another way? Thanks.
When matching against an array, if you specify the query like this:
{ exercises: { _id: exerciseID } }
MongoDB tries to do an exact match on the document. So in this case, MongoDB would only match documents in the exercises array of the exact form { _id: ObjectId("...") }. Because documents in the exercises have other fields, this will never produce a match, even if the _ids are the same.
What you want to do instead is query a field of the documents in the array. The complete query document would then look like this:
{
user: user.id,
"exercises._id": exerciseID
}
You can perform both find and update in one step. Try this:
db.Workout.updateOne(
{
"user": ObjectId("5fc7d6b9bbd9473a24d3ab3e"),
},
{
$pull: {
"exercises.$[exercise].sets": {
"_id": ObjectId("6039709fe0c7d52970d3fa30") // <--- Set ID
}
}
},
{
arrayFilters: [
{
"exercise._id" : ObjectId("6039709fe0c7d52970d3fa2e") // <--- Exercise ID
}
]
}
);
Related
I'm trying to update and object inside array in MongoDB.
my model is:
let userSchema = new mongoose.Schema({
userName: {
type: String
},
password: {
type: String
},
history: []
});
And inside history each element is from the next type:
id, array(named ing_array) and boolean field called favorite.
I'm trying to update the favorite field with mongoose with the userName and the id.
I tried to do this query and I didn't succed.
Could some one tell me whats worng?
[object photo]: https://i.stack.imgur.com/2mYpP.png
User.findOneAndUpdate(
{ "userName": user_name, "history.id": id },
{ "$set": { "history.$.favorite": true }}
);
You have to use arrayFilters in this way:
db.collection.update({
"userName": "uname",
"history.id": 1
},
{
"$set": {
"history.$[element].favorite": false
}
},
{
"arrayFilters": [
{
"element.id": 1
}
]
})
Note that update query has the format: update(query, update, options) (Check the docs).
When you do { "userName": user_name, "history.id": id } you are telling mongo "Give me all documents where userName is user_name and array history has an id with value id. This return all history array because it belows to the document.
To update an specific object into the array is neccessary to use arrayFilters to tell mongo which object do you want to update. In this case the object where id is equal to 1. You can use as you want to match wit your requirements.
Example here
This has been extensively covered here, but none of the solutions seems to be working for me. I'm attempting to remove an object from an array using that object's id. Currently, my Schema is:
const scheduleSchema = new Schema({
//unrelated
_id: ObjectId
shifts: [
{
_id: Types.ObjectId,
name: String,
shift_start: Date,
shift_end: Date,
},
],
});
I've tried almost every variation of something like this:
.findOneAndUpdate(
{ _id: req.params.id },
{
$pull: {
shifts: { _id: new Types.ObjectId(req.params.id) },
},
}
);
Database:
Database Format
Within these variations, the usual response I've gotten has been either an empty array or null.
I was able slightly find a way around this and accomplish the deletion by utilizing the main _id of the Schema (instead of the nested one:
.findOneAndUpdate(
{ _id: <main _id> },
{ $pull: { shifts: { _id: new Types.ObjectId(<nested _id>) } } },
{ new: true }
);
But I was hoping to figure out a way to do this by just using the nested _id. Any suggestions?
The problem you are having currently is you are using the same _id.
Using mongo, update method allows three objects: query, update and options.
query object is the object into collection which will be updated.
update is the action to do into the object (add, change value...).
options different options to add.
Then, assuming you have this collection:
[
{
"_id": 1,
"shifts": [
{
"_id": 2
},
{
"_id": 3
}
]
}
]
If you try to look for a document which _id is 2, obviously response will be empty (example).
Then, if none document has been found, none document will be updated.
What happens if we look for a document using shifts._id:2?
This tells mongo "search a document where shifts field has an object with _id equals to 2". This query works ok (example) but be careful, this returns the WHOLE document, not only the array which match the _id.
This not return:
[
{
"_id": 1,
"shifts": [
{
"_id": 2
}
]
}
]
Using this query mongo returns the ENTIRE document where exists a field called shifts that contains an object with an _id with value 2. This also include the whole array.
So, with tat, you know why find object works. Now adding this to an update query you can create the query:
This one to remove all shifts._id which are equal to 2.
db.collection.update({
"shifts._id": 2
},
{
$pull: {
shifts: {
_id: 2
}
}
})
Example
Or this one to remove shifts._id if parent _id is equal to 1
db.collection.update({
"_id": 1
},
{
$pull: {
shifts: {
_id: 2
}
}
})
Example
I have a collection Users:
{
_id: "5cds8f8rfdshfd"
name: "Ted"
attending: [ObjectId("2cd9fjdkfsld")]
}
I have another collection Events:
{
_id: "2cd9fjdkfsld"
title: "Some Event Attended"
},
{
_id: "34dshfj29jg"
title: "Some Event NOT Attended"
}
I would like to return a list of all events being attended by a given user. However, I need to do this query from the Events collection as this is part of a larger query.
I have gone through the following questions:
$lookup on ObjectId's in an array - This question has the array as a local field; mine is foreign
MongoDB lookup when foreign field is an array of objects - The array is of objects themselves
MongoDB lookup when foreign field is an array
I have tried various ways of modifying the above answers to fit my situation but have been unsuccessful. The second answer from the third question gets me closest but I would like to filter out unmatching results rather than have them returned with a value of 0.
My desired output:
[
{
_id: "2cd9fjdkfsld"
title: "Some Event Attended"
},
]
One option would be like this:
db.getCollection('Events').aggregate({
$lookup: // join
{
from: "Users", // on Users collection
let: { eId: "$_id" }, // keep a local variable "eId" that points to the currently looked at event's "_id"
pipeline: [{
$match: { // filter where
"_id": ObjectId("5c6efc937ef75175b2b8e7a4"), // a specific user
$expr: { $in: [ "$$eId", "$attending" ] } // attends the event we're looking at
}
}],
as: "users" // push all matched users into the "users" array
}
}, {
$match: { // remove events that the user does not attend
"users": { $ne: [] }
}
})
You could obviously get rid of the users field by adding another projection if needed.
I'm trying to create a watch list where users can watch items. I was trying to create it by adding a watchlist field to my users collection. The watchlist would be an array of IDs corresponding to other items.
Users Collection:
id: ObjectId
name: string
watchlist: array i.e. [9872, 342, 4545, 234, 8745]
The question I have is related to querying this structure. I want to be able to write a query where I pass in a user id and an array of ~20 IDs and check which of those IDs the user watches (i.e. which of them exists in the watchlist field for that user).
I tried this initially:
db.users.find({
_id: 507c35dd8fada716c89d0013,
watchlist: { $in: [342, 999, 8745, etc...] }
});
But this gives me the list of users that contain any of those watchlist items, which is not what I want. What I actually want is a response containing an array like this:
{
id: 342,
exists: true
},
{
id: 999,
exists: false
},
{
id: 8745,
exists: true
}
I'd even be ok just getting an array of items that match:
{
_id: 507c35dd8fada716c89d0013,
watching: [342, 8745]
}
Is this doable, or would I be better off moving the watchlist to a separate collection with users as an array? (My concern with the latter approach is that a user will only watch a few hundred items, but tens of thousands of users could potentially watch the same item.)
You can easily achieve the second output using $setIntersection operator.
db.users.aggregate(
[ {$match:{"_id": 507c35dd8fada716c89d0013}},
{ $project: { "watching": { $setIntersection: [ "$watchlist", [ 342, 999, 8745 ] ] } } }
]
)
In Mongoose, lets say I have a User object pulled from MongoDB and that user has an array of Interests. Now I get an instance of one of that user's Interests.
var user = ...
var interest = ...
... //Make some changes to interest.
How do I update that Interest object (after making some changes to it) within the User array in the DB?
Edit
Here is my current code. It doesn't work and doesn't give an error.
User.update(
{
'_id': user._id,
'interests._id': interest._id
},
{
'$set': {
'interests.$.xyzProperty': interest.xyzProperty
}
},
function(err,obj){//some error checking}
);
If you set an if for each interest, you can access the interest by the $ operator.
user document
{
_id: ObectId('54b568531ef35a7c348f21f2'),
interests: [
{
_id: 12345,
title: 'Tacos',
description: 'I Love tacos'
},
{...},
{...},
]
}
If I know which interest sub document I want to update, I simply query it like so:
UserModel.find({_id: ObectId('54b568531ef35a7c348f21f2'), 'interests.i_d': 12345}).lean().exec(function (err, user) {
var interest = ... //find specific interest
interest.description = 'I love tacos... Like, a lot'.
UserModel.update(
{
_id: user._id,
'interests._id': interest._id
},
{
$set: {
'interests.$.description': interest.description
}
},
function (err, update) {
console.log(err, update);
}
);
});
This uses the $ positional operator and updates the specific sub document(or item in an array).