I am trying to count the number of models in a collection based on a property:
I have an upvote model, that has: post (objectId) and a few other properties.
First, is this good design? Posts could get many upvotes, so I didn’t want to store them in the Post model.
Regardless, I want to count the number of upvotes on posts with a specific property with the following and it’s not working. Any suggestions?
upvote.count({‘post.specialProperty’: mongoose.Types.ObjectId(“id”), function (err, count) {
console.log(count);
});
Post Schema Design
In regards to design. I would design the posts collection for documents to be structured as such:
{
"_id" : ObjectId(),
"proprerty1" : "some value",
"property2" : "some value",
"voteCount" : 1,
"votes": [
{
"voter": ObjectId()// voter Id,
other properties...
}
]
}
You will have an array that will hold objects that can contain info such as voter id and other properties.
Updating
When a posts is updated you could simply increment or decrement the voteCountaccordingly. You can increment by 1 like this:
db.posts.update(
{"_id" : postId},
{
$inc: { voteCount: 1},
$push : {
"votes" : {"voter":ObjectId, "otherproperty": "some value"}
}
}
)
The $inc modifier can be used to change the value for an existing key or to create a new key if it does not already exist. Its very useful for updating votes.
Totaling votes of particular Post Criteria
If you want to total the amount for posts fitting a certain criteria, you must use the Aggregation Framework.
You can get the total like this:
db.posts.aggregate(
[
{
$match : {property1: "some value"}
},
{
$group : {
_id : null,
totalNumberOfVotes : {$sum : "$voteCount" }
}
}
]
)
Related
Let say I have a collection of Person{email: 'actual email', ..other data} and want to query if Person exists with given email and retrieve it data if so or get a null if not.
If i want to do that once than no problem just do a query, through mongoose using Person.findOne() or whatever.
But what if I have to do a check for 25-100 given emails? Of course I can just send a tons of requests to mongodb and retrieve the data but it seems a vast of network.
Is there a good and perfomant way to query a mongodb with multiple clauses in single batch like findBatch([{email: 'email1'}, {email: 'email2'}...{email: 'emailN'} ]) and got as result [document1,null,document3,null, documentN] where null is for not matched find criterias?
Currently I see only one option:
Huge find with single {email: $in: [] } query and that do a matching through the searching on the server side in application logic. Cons: quite cumbersome and error prone if you have more than one search criteria.
Is there any better ways to implement such thing?
Try this:
Replace the arrayOfEmails with your query array
Replace emailField with the actual name in your db documents
db.collName.aggregate([
{
"$match" : {
"emailField" : {
"$in" : arrayOfEmails
}
}
},
{
"$group" : {
"_id" : null,
"docs" : {
"$push" : {
"$cond" : [
{
"$in" : [
arrayOfEmails,
[
"$emailField"
]
]
},
"$$ROOT",
null
]
}
}
}
}
])
I have lists of data which I want to save and if already exist update.
I can do that using loop. But Is there any other way like insertMany which only supports insert but I want to insert and update too in bulk.
You can use the bulk update feature that Mongo driver provides. Instead of invoking the transactions in a loop, you may add them to a bulk transaction and execute as a batch.
First you need to initialize the bulk operation, ordered / unordered:
var bulk = db.collection.initializeUnorderedBulkOp();
or
var bulk = db.collection.initializeOrderedBulkOp();
Then you can go on adding transactions to the bulk object.
bulk.insert( {
// attributes
} ); // insert operation
or
bulk.find( {
// query attributes
} ).update( {
$set: {
// set attributes
} } ); // update operation
In the end you need to call
bulk.execute();
I don't know if this would serve your purpose.
Please refer this link:
https://docs.mongodb.com/manual/reference/method/Bulk/
Use updateMany with option { upsert: true } which update the document if it is already exists otherwise insert the new document.
Find below example with restaurant collection
{ "_id" : 1, "name" : "Central Perk Cafe", "violations" : 3 }
{ "_id" : 2, "name" : "Rock A Feller Bar and Grill", "violations" : 2 }
{ "_id" : 3, "name" : "Empire State Sub", "violations" : 5 }
{ "_id" : 4, "name" : "Pizza Rat's Pizzaria", "violations" : 8 }
The query below update the documents with violations equal to 4 and if the document not exists insert new document.
db.restaurant.updateMany(
{ violations: 4 },
{ $set: { "name" : "Eat and Treat" } },
{ upsert: true }
);
Find more details here:
https://docs.mongodb.com/manual/reference/method/db.collection.updateMany/
I have a straightforward mongo collection with an array of subdocuments. I'm trying to do the oft asked "upsert a subdocument in an array". I have read all questions on this topic, but can't seem to get it to work.
Data structure for game_managers:
{
"_id" : ObjectId("555cf465715ff974fb09221f"),
"game_id" : "123456789",
"players" : [
{
"request_email" : "thebigcheese#foobar.com",
"request_notes" : "I love mongo!",
"user_id" : ObjectId("551eb55f555b404d68b88063")
},
{
"request_email" : "morecowbell#example.com",
"request_notes" : "I love oysters!",
"user_id" : ObjectId("551eb55f555b404d68b88063")
}
]
}
When I try to Create / Update with the following code, it always overwrites the first element. I can't get it to even
var col = db.mongo.collection('game_managers');
// Upsert a game manager record for the game
col.update( {game_id:game.place_id}, {$setOnInsert:{game_id:game.game_id}}, { upsert: true }, function(err, result, upserted) {
// Append or update game manager record.
col.update(
{game_id:game.place_id},
{$addToSet: {"players":fields}},
function(err, result) {
next();
}
);
});
I modelled the code from this similar question however it doesn't apply to arrays of subdocuments. I do not want to $pull, and then $push a new element, as the subdocument will ultimately have timestamps and some comments[{},{},{}] subdocs on them.
consider the following records:
user record
{
"_id" : ObjectId("5234ccb7687ea597eabee677"),
"class" : [
{ "_id" : ObjectId("5234ccb7687ea597eabee671", "num" : 10, "color" : "blue" },
{ "_id" : ObjectId("5234ccb7687ea597eabee672", "num" : 100, "color" : "blue" }
]
}
this user has two class sub records, now I need a query that finds all users that have class property where "class._id" has a value of at least one users "class._id"
here is a more detail example:
suppose there is four user:
A:{_id:432645624232345,class:[{_id:123,name:'foo'}]}
B:{_id:432645624232555,class:[{_id:555,name:'foo'},{_id:123,name:'foo'}]}
C:{_id:432645344232345,class:[{_id:555,name:'foo'},{_id:111,name:'www'}]}
D:{_id:432644444232345,class:[{_id:222,name:'sss'},{_id:555,name:'www'},{_id:123,name:'foo'}]}
now if B login , I need to query all the user whose class subdocument contains at least one document which's _id==555 or _id==123 (555 and 123 come from B user), in this case the query result should be:
A:{_id:432645624232345,class:[{_id:123,name:'foo'}]} // match _id=123
B:{_id:432645624232555,class:[{_id:555,name:'foo'},{_id:123,name:'foo'}]} //match _id=123 and _id=555
C:{_id:432645344232345,class:[{_id:555,name:'foo'},{_id:111,name:'www'}]} //match _id=555
D:{_id:432644444232345,class:[{_id:222,name:'sss'},{_id:555,name:'www'},{_id:123,name:'foo'}]} ///match _id=123 and _id=555
which is all the user.
so far i get this:
{"class._id" : { $in : ["5234ccb7687ea597eabee671", "5234ccb7687ea597eabee672"] } }
but when different user login the class._id query condition is different. So is there any operator to do this
{"class._id" : { $in : req.user.class } }
hope I made myself clear.
In order to achieve what you want, first you must isolate the class _ids in an array, and then use it in the query argument.
var classIds = [];
var i = 0;
while (i < req.user.class.length) {
classIds.push(req.user.class[i]._id);
i++;
}
After that you can use classIds array in the query:
{"class._id" : { $in : classIds } }
The following query condition would give you all the users that have at least one class with id equal to any of the elements in the given array:
{"class._id" : { $in : ["5234ccb7687ea597eabee671", "5234ccb7687ea597eabee672"] } }
In the array for the $in clause you may provide any id's you needed , comma separated.
In addition, if you needed such, the below query condition should check for existence of nested document within "class" property that has a property "_id" :
{ "class._id" : { $exists : true } }
Both conditions should work no matter if "class._id" is a single-valued property or an array (mongo supports that).
i have collection of objects inside an invitation, having hard time to filter particular object and trigger it's boolean field.
Document:
"Invitation" : [
{
"__v" : 0,
"userID" : ObjectId("54afaabd88694dc019d3b628"),//ObjectId of personA
"__t" : "USER",
"_id" : ObjectId("54b5022b583973580c706784"),
"Accepted" : false
},
{
"__v" : 0,
"userID" : ObjectId("54af6ce091324fd00f97a15f"),//ObjectId of personB
"__t" : "USER",
"_id" : ObjectId("54bde39cdd55dd9016271f14"),
"Accepted" : false
}
]
here i have only two objects inside Invitation array,it can be more than two.
Let's say personA and personB send me Invitation, so two different invitation objects are inserted into database having different fields, with objectId of both persons(userID in above document), now if i accept only invitation of personA, it should trigger accepted field of personA object only, here is what i tried so far, but not working as per expectation.
Controller:
User.find({_id: req.user._id},'Invitation',function(err,docs) {
if (err) {
console.log(err);
}
var results = [];
async.each(docs,function(doc,callback) {
async.each(doc.Invitation,function(invite,callback) {
User.findOneAndUpdate(
{'_id': doc._id, 'Invitation._id': invite._id},
{'$set': {'Invitation.$.Accepted': !invite.Accepted}},
function(err,doc) {
results.push(doc);
callback(err);
}
);
},callback);
},function(err) {
if (err)
console.log(err);
console.log('end'+results);
});
});
finally i am looking for a query which can be used to filter a single element or object, like if i accept invitation of personA then Accepted field of personA object should be set to true.
i would be really helpful if some logic is provided.
Thank you
Not a very clear question. But it seems all you really need to do here is just match the only sub-document you want to update in the first place:
User.find(
{
"_id": "req.user._id",
"Invitation._id": personA.id
},
{ "Invitation.$": 1 },
function(err,docs) {
// and continue
}
);
This is the form of the positional $ operator in a "projection" context. Where only the "singular" matched element is returned.
Once you have a "singular" result, then all the other code works as designed.
I should know after all because I wrote it for you. Not that you are paying any decent respect to that.
Update on Aggregate in Mongodb
Toggle boolean value of subdocuments
Or personA.userID or whatever makes it work.
Just use the unique identifier for the "user" where you expect that to match the query conditions.
You can do this:
db.user.update({"invitation.userID": 1}, {"$set" : {"invitation.$.Accepted" : true}});
Replacing the value 1 with the user ID you want to update.
The code is in the syntax of MongoShell, simply convert to driver syntax you are using
The operator used was the $. According to the documentation: The positional $ operator identifies an element in an array to update without explicitly specifying the position of the element in the array. To project, or return, an array element from a read operation, see the $ projection operator.
For more details see: http://docs.mongodb.org/manual/reference/operator/update/positional/