Suppose our document looks like this
{
a:1,
b:[
{c:120,d:100},
{c:121,d:110}
]
}
Now how could I upsert new objects in this array?
Suppose I want to perform update on the above document and add {c:200,d:120} to b so my expected result looks like this
{
a:1,
b:[
{c:120,d:100},
{c:121,d:110},
{c:200,d:120}
]
}
Also the update will of $inc, meaning suppose I want to increment d by 200 if c is present(lets say c is 200 and it is already present in the above document), if not present then I want to upsert the document itself.
Any help would be much appreciated.
It can be achieved using the $push update command.
db.<Collection-Name>.updateOne({"a": 1}, {"$push": {"b": {"c":200, "d":120}}})
Note: Use $addToSet if you don't want duplicates elements inside the array
UPDATE:
I don't think your precise requirement can't be achieved by a single command.
Your exact requirement can be achieved by the below script:
if (db.test9.findOne({"_id": ObjectId("5f19402abbc59a3864783fc7"), "b.c": 200}, {"_id": 1}) != null) {
db.test9.updateOne({
"_id": ObjectId("5f19402abbc59a3864783fc7"),
"b.c": 200,
}, {
"$set": {
"b.$.d": 120
}
})
} else {
db.test9.updateOne({
"_id": ObjectId("5f19402abbc59a3864783fc7"),
}, {
"$push": {
"b": {
"c":200, "d":120
}
}
});
}
Related
I am fairly new to MongoDB and cant seem to find a solution to this problem.
I have a database of documents that has this structure:
{
id: 1
elements: [ {elementId: 1, nr1: 1, nr2: 3}, {elementId:2, nr1:5, nr2: 10} ]
}
I am looking for a query that can add a value nr3 which is for example nr2/nr1 to all the objects in the elements array, so that the resulting document would look like this:
{
id: 1
elements: [ {elementId: 1, nr1: 1, nr2: 3, nr3:3}, {elementId:2, nr1:5, nr2: 10, nr3: 2} ]
}
So I imagine a query along the lines of this:
db.collection.updateOne({id:1}, {$set:{"elements.$[].nr3": nr2/nr1}})
But I cant find how to get the value of nr2 and nr1 of the same object in the array.
I found some similar questions on stackoverflow stating this is not possible, but they were 5+ years old, so I thought maybe they have added support for something like this.
I realize I can achieve this with first querying the document and iterate over the elements-array doing updates along the way, but for the purpose of learning I would love to see if its possible to do this in one query.
You can use update with aggregation pipeline starting from MongoDB v4.2,
$map to iterate loop of elements
divide nr2 with nr1 using $divide
merge current object and new field nr3 using $mergeObjects
db.collection.updateOne(
{ id: 1 },
[{
$set: {
elements: {
$map: {
input: "$elements",
in: {
$mergeObjects: [
"$$this",
{ nr3: { $divide: ["$$this.nr2", "$$this.nr1"] } }
]
}
}
}
}
}]
)
Playground
db.collection.update(
{ id:1},
{ "$set": { "elements.$[elem].nr3":elements.$[elem].nr2/elements.$[elem].nr1} },
{ "multi": true }
);
I guess this should work
I'm not sure if Ihave to get the document ,change the object an d update it on the database or if I can update the document on one step
on this document:
{
"_id":{"$oid":"5fb15c68daa5c11cf5d6d4b3"},"state":[],
"users":[
{"_id":{"$oid":"5fb15c68daa5c11cf5d6d4b4"},"user":{"$oid":"5f81eb91d537dc3baf443a84"},"calification":0},
{"_id":{"$oid":"5fb15c9cdaa5c11cf5d6d4b5"},"user":{"$oid":"5fa6f98f15e96c1125b905a9"},"calification":0}
],
"test":{"$oid":"5f986af2baa88b2d30760961"},
"__v":1}
I know the document id and the users array element id, its possible to delete it in one query?
UPDATE:
I'm using , this code but nothing its done
Game.update({
"_id": req.body.game_id,
},
{
"$pull": {
"users": {
"user": '5f81eb91d537dc3baf443a84'
}
}
})
Yes, you can do in one query.
If I've not missunderstood the question, you only need this:
db.collection.update({
"_id": document_id,
},
{
"$pull": {
"users": {
"_id": user_id_to_remove
}
}
})
You look for the document and then $pull the element which has _id 1 (or whatever you want).
Example here
Note that you can use user field if you want instead of _id.
Assuming we have a document in my MongoDB collection like the following:
{
"_id": "coffee",
"orders": [ "espresso", "cappuccino", "espresso", ... ],
}
How do I use a single update statement that ensures there are exactly say 2 espressos in this document, without knowing how many there are to begin with?
I know that using 2 consecutive statements I can do
db.test.update(
{ _id: "coffee" },
{ "$pull": { "orders": "espresso" } }
);
followed by
db.test.update(
{ "_id": "coffee" },
{ "$push": { "orders": { "$each": ["espresso", "espresso"] } } }
);
But when combining both into a single statement, MongoDB balks with an error 40, claiming Updating the path 'orders' would create a conflict at 'orders' (understandable enough - how does MongoDB what to do first?).
So, how can I do the above in a single statement? Please note that since I'll be using the above in the context of a larger unordered bulk operation, combining the above in an ordered bulk operation won't work.
Thanks for your help!
We can use $push (to add an element into an array) in update to atomically update a single document containing the array
However, I could not find a way to atomically add a new key to a map in a document.
I could
* read the document,
* read the map in it,
* update the map in my code and
* update the document in my code.
But that is not atomic.
I am only dealing with a single document but that document has a map.
Is there a way I can update (add a new key) map atomically?
Dot notation with the $set operator is how you address individual elements.
Take the following document:
{
"_id": 1,
"map": {
"field2": 1
}
}
In order to add "field3" to the map you update like this:
db.collection.update({ "_id": 1 }, { "$set": { "map.field3": 2 } })
So now your document looks like this:
{
"_id": 1,
"map": {
"field2": 1,
"field3": 2
}
}
It looks like you(/I ) cannot have both upsert and an array element update operation.
If you do (python):
findDct = {
"_id": ObjectId("535e3ab9c36b4417d031402f"),
'events.ids': '176976332'
}
print col.update(findDct, {"$set" : {"events.$.foo": "bar"} }, upsert=True)
It will throw:
pymongo.errors.DuplicateKeyError: insertDocument :: caused by :: 11000 E11000
duplicate key error index: test.col.$_id_ dup key: { : ObjectId('535e3ab9c36b4417d031402f') }
This happens because "_id" is of course an index and mongo tries to insert the document as a new since the find query fails on its 'events.ids': '176976332' part (cheat).
Is it possible to update an unknown element in array with upsert True/how?
Yes it is, but you are going about it in the wrong way. Rather than make "finding" the element that you are not sure whether it exists or not, then try to apply the $addToSet operator instead:
db.collection.update(
{ "_id": ObjectId("535e3ab9c36b4417d031402f" },
{
"$addToSet": { "events": { "foo": "bar" } }
},
{ "upsert": true }
)
Please also note from the positional $ operator documentation that you should not use the $ operator with "upserts" as this will result in the field name being interpreted as a "literal" ( which includes the value as in "events.$.foo" ) and that will be the actual field inserted into the document.
Try to make sure that your array "insert/upsert" operations specify the whole array content in order to make this work.
Another adaptation is with the "bulk" methods, the pymongo driver already has a nice API for this, but this is a general form:
db.runCommand({
"update": "collection",
"updates": [
{
"q": { "_id": ObjectId("535e3ab9c36b4417d031402f" } },
"u": {
"$addToSet": {
"events": {
"foo": "bar", "bar": "baz"
}
}
},
"upsert": true
},
{
"q": { "_id": ObjectId("535e3ab9c36b4417d031402f" } },
"u": {
"$set": { "events.foo": "bar" }
}
}
]
})
But still being very careful that you are not producing duplicates in your sub-document array if you can clearly see the case there. But it is a method, as each update will cascade down even if the first form failed to add anything. Not the best case example, but I hope you see the point.