Sorry if this is pretty basic, but I'm a mongodb newbie and haven't been able to find an answer to this:
Let's say I'm doing the following:
db.collection("bugs").updateOne({ _id: searchId }, { $set: { "fixed": true }}
How to set "fixed" to the contrary of whatever the last value of "fixed" was? Without any additional queries? Something like { $set: { "fixed": !fixed }}
It is not really possible to achieve this in MongoDB as of now in just one operation by sticking to the idea of storing boolean values (might be possible in future versions of MongoDB). But, there is a workaround to do this by storing bits (0 or 1) to represent true or false instead of boolean values and performing bitwise xor operation on those in MongoDB as follows:
db.collection("bugs").updateOne(
{
_id: searchId
},
{
$bit : {
fixed: {
xor: NumberInt(1)
}
}
}
)
Please note that you also have to store 0 as NumberInt(0) to represent false and 1 as NumberInt(1) to represent true in the fixed prop as MongoDB by default treats all numbers as floating-point values.
This is not possible in MongoDB. You have to retrieve the doc from the db and then update it:
var doc = db.collection("bugs").findOne({ _id: searchId });
db.collection("bugs").updateOne({ _id: searchId }, { $set: { "fixed": !doc.fixed } }
Yes, it's possible to do that with MongoDB, of course !! ... just use the find's forEach feature like this:
db.collection("bugs").find({ _id: searchId }).forEach(function(bugDoc) {
db.collection("bugs").updateOne({ _id: searchId }, { $set: { "fixed": !bugDoc.fixed }});
});
NOTE: bugDoc contains all the fields of the original document and you can make all the calculations and changes you want in this double operation update
Related
I have the following object stored in MongoDb. I am sending a messageRead attribute inside my messages array.
I have tried:
collection.updateOne({ '_id': ObjectId(employeeID) },
{
"$set": {
"userObject.messages.message.message_uuid" : { employeeMessageUpdateUUID, "messageRead" : employeeMessageRead }
}
but it does not work. I find the object i'm looking for through the _id, and then try to find the message using the message_uuid however the messageRead attribute is not updating. I am clearly using the wrong Mongo query.. What should my $set look like?
You can use $ operator to do that:
collection.updateOne(
{
'_id': ObjectId(employeeID),
'userObject.messages.message.message_uuid': employeeMessageUpdateUUID
},
{
$set: { 'userObject.messages.$.message.messageRead': employeeMessageRead }
}
)...
I've stumbled upon some very strange behavior with MongoDB. For my test case, I have an MongoDB collection with 9 documents. All documents have the exact same structure, including the fields expired_at: Date and location: [lng, lat].
I now need to find all documents that are not expired yet and are within a bounding box; I show match documents on map. for this I set up the following queries:
var qExpiry = {"expired_at": { $gt : new Date() } };
var qLocation = { "location" : { $geoWithin : { $box : [ [ 123.8766, 8.3269 ] , [ 122.8122, 8.24974 ] ] } } };
var qFull = { $and: [ qExpiry, qLocation ] };
Since the expiry date is long in the past, and when I set the bounding box large enough, the following queries give me all 9 documents as expected:
db.docs.find(qExpiry);
db.docs.find(qLocation);
db.docs.find(qFull);
db.docs.find(qExpiry).sort({"created_at" : -1});
db.docs.find(qLocation).sort({"created_at" : -1});
Now here's the deal: The following query returns 0 documents:
db.docs.find(qFull).sort({"created_at" : -1});
Just adding sort to the AND query ruins the result (please note that I want to sort since I also have a limit in order to avoid cluttering the map on larger scales). Sorting by other fields yield the same empty result. What's going on here?
(Actually even stranger: When I zoom into my map, I sometimes get results for qFull, even with sorting. One could argue that qLocation is faulty. But when I only use qLocation, the results are always correct. And qExpiry is always true for all documents anyway)
You may want to try running the same query using the aggregation framework's $match and $sort pipelines:
db.docs.aggregate([
{ "$match": qFull },
{ "$sort": { "created_at": -1 } }
]);
or implicitly using $and by specifiying a comma-separated list of expressions as in
db.docs.aggregate([
{
"$match": {
"expired_at": { "$gt" : new Date() },
"location" : {
"$geoWithin" : {
"$box" : [
[ 123.8766, 8.3269 ],
[ 122.8122, 8.24974 ]
]
}
}
}
},
{ "$sort": { "created_at": -1 } }
]);
Not really sure why that fails with find()
chridam suggestion using the aggregation framework of MongoDB proved to be the way to go. My working query now looks like this:
db.docs.aggregate(
[
{ $match : { $and : [qExpiry, qLocation]} },
{ $sort: {"created_at": -1} }.
{ $limit: 50 }.
]
);
Nevertheless, if any can point out way my first approach did not work, that would be very useful. Simply adding sort() to a non-empty query shouldn't suddenly return 0 documents. Just to add, since I still tried for a bit, .sort({}) return all documents but was not very useful. Everything else failed including .sort({'_id': 1}).
Using Mongoose, How can I add more items to an object without replacing existing ones?
User.findOneAndUpdate(
{ userId: 0 },
{ userObjects: { newItem: value } }
);
The problem with above code is that it clears whatever was there before and replaces it with newItem when I wanted it just to add another item to userObjects(Like push function for javascript arrays).
Use dot notation to specify the field to update/add particular fields in an embedded document.
User.findOneAndUpdate(
{ userId: 0 },
{ "userObjects.newerItem": newervalue } }
);
or
User.findOneAndUpdate(
{ userId: 0 },
{ "$set":{"userObjects.newerItem": newervalue } }
);
or Use $mergeObjects aggregation operator to update the existing obj by passing new objects
User.findOneAndUpdate(
{"userId":0},
[{"$set":{
"userObjects":{
"$mergeObjects":[
"$userObjects",
{"newerItem":"newervalue","newestItem":"newestvalue"}
]
}
}}]
)
According to your question, i am guessing userObjects is an array.
You can try $push to insert items into the array.
User.findOneAndUpdate(
{ userId: 0 },
{ $push : {"userObjects": { newItem: value } }},
{safe :true , upsert : true},function(err,model)
{
...
});
For more info, read MongoDB $push reference.
Hope it helps you. If you had provided the schema, i could have helped better.
Just create new collection called UserObjects and do something like this.
UserObject.Insert({ userId: 0, newItem: value }, function(err,newObject){
});
Whenever you want to get these user objects from a user then you can do it using monogoose's query population to populate parent objects with related data in other collections. If not, then your best bet is to just make the userObjects an array.
This question already has answers here:
MongoDB : aggregation framework : $match between fields
(2 answers)
Closed 6 years ago.
So I have this query,
db.collection.find({$where: "this.field1 !== this.field2"})
But now I need to create a similar query and aggregate the results in a complex query which tried and true, only can be done by using the aggregation pipeline or go "cannon for a fly" and use the mapReduce option.
Since I want to avoid mapReduce, is there a way to achieve something similar to the {$where: "this.field1 !== this.field2"} approach?
Some observations, an answer to the general approach to solve the situation above is most desirable, but in case that is not possible, in order to solve my problem, I can also use the raw value in the query with the following restrictions. I need to find what follows
db.collection.find({ $or :[
{field1: value},
{field2: value}
], $and: [
{ field1: {$not: {$eq: value}}},
{ field2: {$not: {$eq: value}} }
]})
I tried the above query but it discards results that contains the value in either field, and what I want is a way to discard the objects that have the same value in both fields at the same time, but obtain the documents that have the value in either field, I usually prefer an one query approach but after reading a lot, I think the only alternative to avoid mapReduce, is to do something like
db.collection.find({$where: "this.field1 === this.field2"}, function (err, results){
var match = { $or :[
{field1: value},
{field2: value}
], {
_id : { $not : {$in: results.map((x) => x._id)}}
}
db.collection([ {$match: match}, {$project: projectionObject}, ...., etc])
})
So I'm going to use the be solution above, which can be optimized a lot, (I just wrote it while writing the question), but I would like to avoid sending an incredibly big list of objectIds back to the database if at all possible. I will refactor it a bit to use matching operators before the where statement
that's complex case, and maybe you could use a trick with $cond inside $project
var projectDataForMatch = {
$project : {
_id : 1, //list all fields needed here
filterThisDoc : {
$cond : {
if : {
$eq : ["$field1", "$filed2"]
},
then : 1,
else : 0
} //or use compare operator $cmp
}
}
}
var match = {
$match : {
filterThisDoc : 1
}
}
db.col.aggregate([projectDataForMatch, match])
you can extend $cond to fit your needs as desired.
In products collection, i have an Array of recentviews which has 2 fields viewedBy & viewedDate.
In a scenario if i already have a record with viewedby, then i need to update it. For e.g if i have array like this :-
"recentviews" : [
{
"viewedby" : "abc",
"vieweddate" : ISODate("2014-05-08T04:12:47.907Z")
}
]
And user is abc, so i need to update the above & if there is no record for abc i have to $push.
I have tried $set as follows :-
db.products.update( { _id: ObjectId("536c55bf9c8fb24c21000095") },
{ $set:
{ "recentviews":
{
viewedby: 'abc',
vieweddate: ISODate("2014-05-09T04:12:47.907Z")
}
}
}
)
The above query erases all my other elements in Array.
Actually doing what it seems like you say you are doing is not a singular operation, but I'll walk through the parts required in order to do this or otherwise cover other possible situations.
What you are looking for is in part the positional $ operator. You need part of your query to also "find" the element of the array you want.
db.products.update(
{
"_id": ObjectId("536c55bf9c8fb24c21000095"),
"recentviews.viewedby": "abc"
},
{
"$set": {
"recentviews.$.vieweddate": ISODate("2014-05-09T04:12:47.907Z")
}
}
)
So the $ stands for the matched position in the array so the update portion knows which item in the array to update. You can access individual fields of the document in the array or just specify the whole document to update at that position.
db.products.update(
{
"_id": ObjectId("536c55bf9c8fb24c21000095"),
"recentviews.viewedby": "abc"
},
{
"$set": {
"recentviews.$": {
"viewedby": "abc",
"vieweddate": ISODate("2014-05-09T04:12:47.907Z")
}
}
)
If the fields do not in fact change and you just want to insert a new array element if the exact same one does not exist, then you can use $addToSet
db.products.update(
{
"_id": ObjectId("536c55bf9c8fb24c21000095"),
"recentviews.viewedby": "abc"
},
{
$addToSet:{
"recentviews": {
"viewedby": "abc",
"vieweddate": ISODate("2014-05-09T04:12:47.907Z")
}
}
)
However if you are just looking for for "pushing" to an array by a singular key value if that does not exist then you need to do some more manual handling, by first seeing if the element in the array exists and then making the $push statement where it does not.
You get some help from the mongoose methods in doing this by tracking the number of documents affected by the update:
Product.update(
{
"_id": ObjectId("536c55bf9c8fb24c21000095"),
"recentviews.viewedby": "abc"
},
{
"$set": {
"recentviews.$": {
"viewedby": "abc",
"vieweddate": ISODate("2014-05-09T04:12:47.907Z")
}
},
function(err,numAffected) {
if (numAffected == 0) {
// Document not updated so you can push onto the array
Product.update(
{
"_id": ObjectId("536c55bf9c8fb24c21000095")
},
{
"$push": {
"recentviews": {
"viewedby": "abc",
"vieweddate": ISODate("2014-05-09T04:12:47.907Z")
}
}
},
function(err,numAffected) {
}
);
}
}
);
The only word of caution here is that there is a bit of an implementation change in the writeConcern messages from MongoDB 2.6 to earlier versions. Being unsure right now as to how the mongoose API actually implements the return of the numAffected argument in the callback the difference could mean something.
In prior versions, even if the data you sent in the initial update exactly matched an existing element and there was no real change required then the "modified" amount would be returned as 1 even though nothing was actually updated.
From MongoDB 2.6 the write concern response contains two parts. One part shows the modified document and the other shows the match. So while the match would be returned by the query portion matching an existing element, the actual modified document count would return as 0 if in fact there was no change required.
So depending on how the return number is actually implemented in mongoose, it might actually be safer to use the $addToSet operator on that inner update to make sure that if the reason for the zero affected documents was not just that the exact element already existed.