I want to be able to pass a dynamic BSON variable to match for mongodb.
Here is what I have tried:
var query = "\"info.name\": \"ABC\"";
and
var query = {
info: {
name: "ABC"
}
}
Neither of these work when passing variable 'query' to match (like below):
$match: {
query
}
but explicitly passing like below does work:
$match: {
"info.name": "ABC"
}
It works when you pass a query object that is like;
var query = {
"info.name": "ABC"
}
and passed into the aggregation pipe like so;
{ $match: query }
You can see its details on MongoDB Node.js Driver Tutorials
You cannot use a JSON object to query nested fields, like;
var query = {
info: {
name: "ABC"
}
}
check here
unless info contains only name field, then it can be used in such a manner. But again you have to pass with { $match: query }, like here
Here is what went wrong
var query = "\"info.name\": \"ABC\"";
{ $match: ""info.name": "ABC"" } // This is single string
Here in this query, we get single string that's why not result filter
But when you are using explicitly passing like this "info.name": "ABC" it work
For data
{
_id: ObjectId(XXXXXXXXXX),
info: { name: "ABC" }
}
You can use this aggregate query
// Create object and use this into [$match][1] stage
const data = { "info.name": "ABC" };
// Use this object in match stag
.aggregate([{ $match: data}])
if you have array of object then you need to use $elemMatch
For data
{
_id: ObjectId(XXXXXXXXXX)
info: [{ name: "ABC" }, { name: "DEF" } ]
}
// use elemMatch if array of object
.aggregate([{ $match: { info: { $elemMatch:{ name: "ABC" }}}}])
As MongoDB documentation says:
To specify a query condition on fields in an embedded/nested document, use dot notation.
The actual problem is that you have your object property name as a variable in your JS code. Please, check how to add a property to a JavaScript object using a variable as the name.
Here is how you can do it:
var propertyName = "info.name"
var query = {}
query[propertyName] = "ABC"
...
Related
I'm trying to return all documents which satisfy document.field.value > document.array.length. I'm trying to do this using MongoClient in ExpressJS and was not able to find answers on SO.
Here is what I have tried but this gives an empty list.
const db = ref()
const c = db.collection(t)
const docs = await c.find({
"stop.time":{$gt: new Date().toISOString()},
"stop.expect": {$gt: { $size: "stop.riders"}}
})
console.log(docs)
Also tried replacing
"stop.expect": {$gt: { $size: "stop.riders"}}
with the below code which does not compile
$expr: {$lt: [{$size: "stop.riders"}, "stop.expect"]}
Sample data:
{ "stop": { "expect":3, "riders": ["asd", "erw", "wer"] } },
{ "stop": { "expect":4, "riders": ["asq", "frw", "wbr"] } }
To filter the query with a complex query involving the calculation, you need to use the $expr operator, which allows the aggregation operators.
Next, within the $expr operator, to refer to the field, you need to add the prefix $.
db.collection.find({
$expr: {
$lt: [
{
$size: "$stop.riders"
},
"$stop.expect"
]
}
})
Demo # Mongo Playground
To compare fields within a document to each other, you must use $expr. It would look like this:
const docs = await c.find({
$expr: { $gt: ["$stop.expect", { $size: "$stop.riders" }] },
});
I omitted the stop.time condition because it's not in your sample data and it's unclear what type of field it is, if it actually is in your data (whether it's a Date or String would be very important).
Note that this sort of query is unable to use an index.
I just can't figure out the query and even if it's allowed to write a single query to push 4 different objects into 4 different arrays deeply nested inside the user Object.
I receive PATCH request from front-end which's body looks like this:
{
bodyweight: 80,
waist: 60,
biceps: 20,
benchpress: 50,
timestamp: 1645996168125
}
I want to create 4 Objects and push them into user's data in Mongo Atlas
{date:1645996168125, value:80} into user.stats.bodyweight <-array
{date:1645996168125, value:60} into user.stats.waist <-array
...etc
I am trying to figure out second argument for:
let user = await User.findOneAndUpdate({id:req.params.id}, ???)
But i am happy to update it with any other mongoose method if possible.
PS: I am not using _id given by mongoDB on purpose
You'll want to use the $push operator. It accepts paths as the field names, so you can specify a path to each of the arrays.
I assume the fields included in your request are fixed (the same four property names / arrays for every request)
let user = await User.findOneAndUpdate(
{ id: req.params.id },
{
$push: {
"stats.bodyweight": {
date: 1645996168125,
value: 80,
},
"stats.waist": {
date: 1645996168125,
value: 60,
},
// ...
},
}
);
If the fields are dynamic, use an object and if conditions, like this:
const update = {};
if ("bodyweight" in req.body) {
update["stats.bodyweight"] = {
date: 1645996168125,
value: 80,
};
}
// ...
let user = await User.findOneAndUpdate(
{ id: req.params.id },
{
$push: update,
}
);
The if condition is just to demonstrate the principle, you'll probably want to use stricter type checking / validation.
try this:
await User.findOneAndUpdate(
{id:req.params.id},
{$addToSet:
{"stats.bodyweight":{date:1645996168125, value:80} }
}
)
Desired Behaviour
Pull a range of objects from an array of objects and push them back to the array at a new index.
For example, pull objects from the array where their index is between 0 and 2, and push them back to the array at position 6.
For reference, in jQuery, the desired behaviour can be achieved with:
if (before_or_after === "before") {
$("li").eq(new_position).before($("li").slice(range_start, range_end + 1));
} else if (before_or_after === "after") {
$("li").eq(new_position).after($("li").slice(range_start, range_end + 1));
}
jsFiddle demonstration
Schema
{
"_id": ObjectId("*********"),
"title": "title text",
"description": "description text",
"statements": [
{
"text": "string",
"id": "********"
},
{
"text": "string",
"id": "********"
},
{
"text": "string",
"id": "********"
},
{
"text": "string",
"id": "********"
},
{
"text": "string",
"id": "********"
}]
}
What I've Tried
I am able to reposition a single object in an array of objects with the code below.
It uses pull to remove the object from the array and push to add it back to the array at a new position.
In order to do the same for a range of objects, I think I just need to modify the $pull and $push variables but:
I can't figure out how to use $slice in this context, either as a projection or an aggregation, in a $pull operation
Because I can't figure out the first bit, I don't know how to attempt the second bit - the $push operation
// define the topic_id to search for
var topic_id = request_body.topic_id;
// make it usable as a search query
var o_id = new ObjectID(topic_id);
// define the statement_id to search for
var statement_id = request_body.statement_id;
// define new position
var new_position = Number(request_body.new_position);
// define old position
var old_position = Number(request_body.old_position);
// define before or after (this will be relevant later)
// var before_or_after = request_body.before_or_after;
// define the filter
var filter = { _id: o_id };
// define the pull update - to remove the object from the array of objects
var pull_update = {
$pull: {
statements: { id: statement_id } // <----- how do i pull a range of objects here
}
};
// define the projection so that only the 'statements' array is returned
var options = { projection: { statements: 1 } };
try {
// perform the pull update
var topic = await collection.findOneAndUpdate(filter, pull_update, options);
// get the returned statement object so that it can be inserted at the desired index
var returned_statement = topic.value.statements[old_position];
// define the push update - to add the object back to the array at the desired position
var push_update = {
$push: {
statements: {
$each: [returned_statement],
$position: new_position
}
} // <----- how do i push the range of objects back into the array here
};
// perform the push update
var topic = await collection.findOneAndUpdate(filter, push_update);
}
Environments
##### local
$ mongod --version
db version v4.0.3
$ npm view mongodb version
3.5.9
$ node -v
v10.16.3
$ systeminfo
OS Name: Microsoft Windows 10 Home
OS Version: 10.0.18363 N/A Build 18363
##### production
$ mongod --version
db version v3.6.3
$ npm view mongodb version
3.5.9
$ node -v
v8.11.4
RedHat OpenShift Online, Linux
Edit
Gradually, figuring out parts of the problem, I think:
Using the example here, the following returns objects from array with index 0 - 2 (ie 3 objects):
db.topics.aggregate([
{ "$match": { "_id": ObjectId("********") } },
{ "$project": { "statements": { "$slice": ["$statements", 0, 3] }, _id: 0 } }
])
Not sure how to use that in a pull yet...
I also looked into using $in (even though i would prefer to just grab a range of objects than have to specify each object's id), but realised it does not preserve the order of the array values provided in the results returned:
Does MongoDB's $in clause guarantee order
Here is one solution to re-ordering results from $in in Node:
https://stackoverflow.com/a/34751295
Here an example with mongo 3.5
const mongo = require('mongodb')
;(async function (params) {
const client = await mongo.connect('mongodb://localhost:27017')
const coll = client.db('test').collection('test')
const from0to99 = Array(100).fill('0').map((_, i) => String(i))
const from5To28 = Array(24).fill('0').map((_, i) => String(i + 5))
const insert = { statements: from0to99.map(_ => ({ id: _ })) }
await coll.insertOne(insert)
const all100ElementsRead = await coll.findOneAndUpdate(
{ _id: insert._id },
{
$pull: {
statements: {
id: { $in: from5To28 }
}
}
},
{ returnOriginal: true }
)
/**
* It shows the object with the desired _id BEFORE doing the $pull
* You can process all the old elements as you wish
*/
console.log(all100ElementsRead.value.statements)
// I use the object read from the database to push back
// since I know the $in condition, I must filter the array returned
const pushBack = all100ElementsRead.value.statements.filter(_ => from5To28.includes(_.id))
// push back the 5-28 range at position 72
const pushed = await coll.findOneAndUpdate(
{ _id: insert._id },
{
$push: {
statements: {
$each: pushBack,
$position: 72 // 0-indexed
}
}
},
{ returnOriginal: false }
)
console.log(pushed.value.statements) // show all the 100 elements
client.close()
})()
This old issue helped
if you want "desired behavior" when mutating arrays ,
you add these to checklist:
array.length atleast==7 if you want to add ,splice at 6
creates a new array if u use concat
mutates orignal if used array.push or splice or a[a.length]='apple'
USE slice() to select between incex1 to index2.
or run a native for loop to select few elements of array or
apply a array.filter() finction.
once you select your elements which needed to be manupulated you mentioned you want to add it to end. so this is the method below.
about adding elements at end:
CONCAT EXAMPLE
const original = ['🦊']; //const does not mean its immutable just that it cant be reassigned
let newArray;
newArray = original.concat('🦄');
newArray = [...original, '🦄'];
// Result
newArray; // ['🦊', '🦄']
original; // ['🦊']
SPLICE EXAMPLE:
const zoo = ['🦊', '🐮'];
zoo.splice(
zoo.length, // We want add at the END of our array
0, // We do NOT want to remove any item
'🐧', '🐦', '🐤', // These are the items we want to add
);
console.log(zoo); // ['🦊', '🐮', '🐧', '🐦', '🐤']
I am having a problem searching for a key of a nested object.
I have search criteria object that may or may not have certain fields I'd like to search on.
The way I'm solving this is to use conditional statements to append to a "match criteria" object that gets passed to the aggregate $match operator. it works well until I need to match to something inside a nested object.
Here is a sample document structure
{
name: string,
dates: {
actived: Date,
suspended: Date
},
address : [{
street: string,
city: string,
state: string,
zip: string
}]
};
My criteria object is populated thru a UI and passed a JSON that looks similar to this:
{
"name": "",
"state": ""
}
And although I can explicitly use "dates.suspended" without issue -
when I try to append address.state to my search match criteria - I get an error.
module.exports.search = function( criteria, callback )
let matchCriteria = {
"name": criteria.name,
"dates.suspended": null
};
if ( criteria.state !== '' ) {
// *** PROBLEM HAPPENS HERE *** //
matchCriteria.address.state = criteria.state;
}
User.aggregate([
{ "$match": matchCriteria },
{ "$addFields": {...} },
{ "$project": {...} }
], callback );
}
I get the error:
TypeError: Cannot set property 'state' of undefined
I understand that I'm specifying 'address.state' when 'address' doesn't exist yet - but I am unclear what my syntax would be surely it woulnd't be matchCriteria['address.state'] or "matchCriteria.address.state"
Is there a better way to do conditional filtering?
For search in Nested Object, You have to use unwind
A query that help you :
//For testing declare criteria as const
let criteria = {name : 'name', 'state' : 'state'};
let addressMatch = {};
let matchCriteria = {
"name": criteria.name,
"dates.suspended": null
};
if ( criteria.state) {
addressMatch = { 'address.state' : criteria.state };
}
db.getCollection('user').aggregate([{
$match :matchCriteria,
},{$unwind:'$address'},
{$match : addressMatch}
])
Firstly check for address, and then access the property as shown:
if(matchCriteria['address']) {
matchCriteria['address']['state'] = criteria['state'];
}
else {
//otherwise
}
This should fix it:
matchCriteria['address.state'] = criteria.state;
For example, I have some documents that look like this:
{
id: 1
name: "foo"
}
And I want to append another string to the current name field value.
I tried the following using Mongoose, but it didn't work:
Model.findOneAndUpdate({ id: 1 }, { $set: { name: +"bar" } }, ...);
Edit:
From Compatibility Changes in MongoDB 3.6:
MongoDB 3.6.1 deprecates the snapshot query option.
For MMAPv1, use hint() on the { _id: 1} index instead to prevent a cursor from returning a document more than once if an intervening write operation results in a move of the document.
For other storage engines, use hint() with { $natural : 1 } instead.
Original 2017 answer:
You can't refer to the values of the document you want to update, so you will need one query to retrieve the document and another one to update it. It looks like there's a feature request for that in OPEN state since 2016.
If you have a collection with documents that look like:
{ "_id" : ObjectId("590a4aa8ff1809c94801ecd0"), "name" : "bar" }
Using the MongoDB shell, you can do something like this:
db.test.find({ name: "bar" }).snapshot().forEach((doc) => {
doc.name = "foo-" + doc.name;
db.test.save(doc);
});
The document will be updated as expected:
{ "_id" : ObjectId("590a4aa8ff1809c94801ecd0"), "name": "foo-bar" }
Note the .snapshot() call.
This ensures that the query will not return a document multiple times because an intervening write operation moves it due to the growth in document size.
Applying this to your Mongoose example, as explained in this official example:
Cat.findById(1, (err, cat) => {
if (err) return handleError(err);
cat.name = cat.name + "bar";
cat.save((err, updatedCat) => {
if (err) return handleError(err);
...
});
});
It's worth mentioning that there's a $concat operator in the aggregation framework, but unfortunately you can't use that in an update query.
Anyway, depending on what you need to do, you can use that together with the $out operator to save the results of the aggregation to a new collection.
With that same example, you will do:
db.test.aggregate([{
$match: { name: "bar" }
}, {
$project: { name: { $concat: ["foo", "-", "$name"] }}
}, {
$out: "prefixedTest"
}]);
And a new collection prefixedTest will be created with documents that look like:
{ "_id" : ObjectId("XXX"), "name": "foo-bar" }
Just as a reference, there's another interesting question about this same topic with a few answers worth reading: Update MongoDB field using value of another field
If this is still relevant, I have a solution for MongoDB 4.2.
I had the same problem where "projectDeadline" fields of my "project" documents were Array type (["2020","12","1"])
Using Robo3T, I connected to my MongoDB Atlas DB using SRV link. Then executed the following code and it worked for me.
Initial document:
{
_id : 'kjnolqnw.KANSasdasd',
someKey : 'someValue',
projectDeadline : ['2020','12','1']
}
CLI Command:
db
.getCollection('mainData')
.find({projectDeadline: {$not: {$eq: "noDeadline"}}})
.forEach((doc) => {
var deadline = doc.projectDeadline;
var deadlineDate = new Date(deadline);
db
.mainData
.updateOne({
_id: doc._id},
{"$set":
{"projectDeadline": deadlineDate}
}
)}
);
Resulting document:
{
_id : 'kjnolqnw.KANSasdasd',
someKey : 'someValue',
projectDeadline : '2020-12-01 21:00:00.000Z'
}