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Filter mongodb data by current month

i try to query find by month in mongodb,
my data in Daq collection is like this:
"
_id" : ObjectId("5f14081c14c08a261b816d57"),
"battery_voltage" : 3673,
"total_usage" : 0.483,
"signal" : 14,
"samplehour" : "2020-07-18T23:59:59-04:00",
"sampledate" : "2020-07-18T23:59:59-04:00",
this is my queries:
let n = moment().month()
let test = await Daq.aggregate([
{$addFields: { "month" : {$month: '$sampledate'}}},
{$match: { month: n}}
]);
i already try this too :
let n = moment().month()
let test = await Daq.aggregate([
{$project: { "month" : {$month: '$sampledate'}}},
{$match: { month: n}}
]);
but the result is always
"message": "can't convert from BSON type string to Date"
how you guys can solve this?

Your sampledate is not saved as a date object but rather as a string. You first need to convert it to a date and then you can use functions such as $month.
$addFields: {
"month": {
$month: {
$toDate: "$sampledate"
}
}
}
https://mongoplayground.net/p/XOdfYtEXqLc
I assume the fact that it's a string is actually a bug in your insert code and you should probably fix that instead.

MongoDB $graphLookup inside update query [duplicate]

In MongoDB, is it possible to update the value of a field using the value from another field? The equivalent SQL would be something like:
UPDATE Person SET Name = FirstName + ' ' + LastName
And the MongoDB pseudo-code would be:
db.person.update( {}, { $set : { name : firstName + ' ' + lastName } );

The best way to do this is in version 4.2+ which allows using the aggregation pipeline in the update document and the updateOne, updateMany, or update(deprecated in most if not all languages drivers) collection methods.
MongoDB 4.2+
Version 4.2 also introduced the $set pipeline stage operator, which is an alias for $addFields. I will use $set here as it maps with what we are trying to achieve.
db.collection.<update method>(
{},
[
{"$set": {"name": { "$concat": ["$firstName", " ", "$lastName"]}}}
]
)
Note that square brackets in the second argument to the method specify an aggregation pipeline instead of a plain update document because using a simple document will not work correctly.
MongoDB 3.4+
In 3.4+, you can use $addFields and the $out aggregation pipeline operators.
db.collection.aggregate(
[
{ "$addFields": {
"name": { "$concat": [ "$firstName", " ", "$lastName" ] }
}},
{ "$out": <output collection name> }
]
)
Note that this does not update your collection but instead replaces the existing collection or creates a new one. Also, for update operations that require "typecasting", you will need client-side processing, and depending on the operation, you may need to use the find() method instead of the .aggreate() method.
MongoDB 3.2 and 3.0
The way we do this is by $projecting our documents and using the $concat string aggregation operator to return the concatenated string.
You then iterate the cursor and use the $set update operator to add the new field to your documents using bulk operations for maximum efficiency.
Aggregation query:
var cursor = db.collection.aggregate([
{ "$project": {
"name": { "$concat": [ "$firstName", " ", "$lastName" ] }
}}
])
MongoDB 3.2 or newer
You need to use the bulkWrite method.
var requests = [];
cursor.forEach(document => {
requests.push( {
'updateOne': {
'filter': { '_id': document._id },
'update': { '$set': { 'name': document.name } }
}
});
if (requests.length === 500) {
//Execute per 500 operations and re-init
db.collection.bulkWrite(requests);
requests = [];
}
});
if(requests.length > 0) {
db.collection.bulkWrite(requests);
}
MongoDB 2.6 and 3.0
From this version, you need to use the now deprecated Bulk API and its associated methods.
var bulk = db.collection.initializeUnorderedBulkOp();
var count = 0;
cursor.snapshot().forEach(function(document) {
bulk.find({ '_id': document._id }).updateOne( {
'$set': { 'name': document.name }
});
count++;
if(count%500 === 0) {
// Excecute per 500 operations and re-init
bulk.execute();
bulk = db.collection.initializeUnorderedBulkOp();
}
})
// clean up queues
if(count > 0) {
bulk.execute();
}
MongoDB 2.4
cursor["result"].forEach(function(document) {
db.collection.update(
{ "_id": document._id },
{ "$set": { "name": document.name } }
);
})

You should iterate through. For your specific case:
db.person.find().snapshot().forEach(
function (elem) {
db.person.update(
{
_id: elem._id
},
{
$set: {
name: elem.firstname + ' ' + elem.lastname
}
}
);
}
);

Apparently there is a way to do this efficiently since MongoDB 3.4, see styvane's answer.
Obsolete answer below
You cannot refer to the document itself in an update (yet). You'll need to iterate through the documents and update each document using a function. See this answer for an example, or this one for server-side eval().

For a database with high activity, you may run into issues where your updates affect actively changing records and for this reason I recommend using snapshot()
db.person.find().snapshot().forEach( function (hombre) {
hombre.name = hombre.firstName + ' ' + hombre.lastName;
db.person.save(hombre);
});
http://docs.mongodb.org/manual/reference/method/cursor.snapshot/

Starting Mongo 4.2, db.collection.update() can accept an aggregation pipeline, finally allowing the update/creation of a field based on another field:
// { firstName: "Hello", lastName: "World" }
db.collection.updateMany(
{},
[{ $set: { name: { $concat: [ "$firstName", " ", "$lastName" ] } } }]
)
// { "firstName" : "Hello", "lastName" : "World", "name" : "Hello World" }
The first part {} is the match query, filtering which documents to update (in our case all documents).
The second part [{ $set: { name: { ... } }] is the update aggregation pipeline (note the squared brackets signifying the use of an aggregation pipeline). $set is a new aggregation operator and an alias of $addFields.

Regarding this answer, the snapshot function is deprecated in version 3.6, according to this update. So, on version 3.6 and above, it is possible to perform the operation this way:
db.person.find().forEach(
function (elem) {
db.person.update(
{
_id: elem._id
},
{
$set: {
name: elem.firstname + ' ' + elem.lastname
}
}
);
}
);

I tried the above solution but I found it unsuitable for large amounts of data. I then discovered the stream feature:
MongoClient.connect("...", function(err, db){
var c = db.collection('yourCollection');
var s = c.find({/* your query */}).stream();
s.on('data', function(doc){
c.update({_id: doc._id}, {$set: {name : doc.firstName + ' ' + doc.lastName}}, function(err, result) { /* result == true? */} }
});
s.on('end', function(){
// stream can end before all your updates do if you have a lot
})
})

update() method takes aggregation pipeline as parameter like
db.collection_name.update(
{
// Query
},
[
// Aggregation pipeline
{ "$set": { "id": "$_id" } }
],
{
// Options
"multi": true // false when a single doc has to be updated
}
)
The field can be set or unset with existing values using the aggregation pipeline.
Note: use $ with field name to specify the field which has to be read.

Here's what we came up with for copying one field to another for ~150_000 records. It took about 6 minutes, but is still significantly less resource intensive than it would have been to instantiate and iterate over the same number of ruby objects.
js_query = %({
$or : [
{
'settings.mobile_notifications' : { $exists : false },
'settings.mobile_admin_notifications' : { $exists : false }
}
]
})
js_for_each = %(function(user) {
if (!user.settings.hasOwnProperty('mobile_notifications')) {
user.settings.mobile_notifications = user.settings.email_notifications;
}
if (!user.settings.hasOwnProperty('mobile_admin_notifications')) {
user.settings.mobile_admin_notifications = user.settings.email_admin_notifications;
}
db.users.save(user);
})
js = "db.users.find(#{js_query}).forEach(#{js_for_each});"
Mongoid::Sessions.default.command('$eval' => js)

With MongoDB version 4.2+, updates are more flexible as it allows the use of aggregation pipeline in its update, updateOne and updateMany. You can now transform your documents using the aggregation operators then update without the need to explicity state the $set command (instead we use $replaceRoot: {newRoot: "$$ROOT"})
Here we use the aggregate query to extract the timestamp from MongoDB's ObjectID "_id" field and update the documents (I am not an expert in SQL but I think SQL does not provide any auto generated ObjectID that has timestamp to it, you would have to automatically create that date)
var collection = "person"
agg_query = [
{
"$addFields" : {
"_last_updated" : {
"$toDate" : "$_id"
}
}
},
{
$replaceRoot: {
newRoot: "$$ROOT"
}
}
]
db.getCollection(collection).updateMany({}, agg_query, {upsert: true})

(I would have posted this as a comment, but couldn't)
For anyone who lands here trying to update one field using another in the document with the c# driver...
I could not figure out how to use any of the UpdateXXX methods and their associated overloads since they take an UpdateDefinition as an argument.
// we want to set Prop1 to Prop2
class Foo { public string Prop1 { get; set; } public string Prop2 { get; set;} }
void Test()
{
var update = new UpdateDefinitionBuilder<Foo>();
update.Set(x => x.Prop1, <new value; no way to get a hold of the object that I can find>)
}
As a workaround, I found that you can use the RunCommand method on an IMongoDatabase (https://docs.mongodb.com/manual/reference/command/update/#dbcmd.update).
var command = new BsonDocument
{
{ "update", "CollectionToUpdate" },
{ "updates", new BsonArray
{
new BsonDocument
{
// Any filter; here the check is if Prop1 does not exist
{ "q", new BsonDocument{ ["Prop1"] = new BsonDocument("$exists", false) }},
// set it to the value of Prop2
{ "u", new BsonArray { new BsonDocument { ["$set"] = new BsonDocument("Prop1", "$Prop2") }}},
{ "multi", true }
}
}
}
};
database.RunCommand<BsonDocument>(command);

MongoDB 4.2+ Golang
result, err := collection.UpdateMany(ctx, bson.M{},
mongo.Pipeline{
bson.D{{"$set",
bson.M{"name": bson.M{"$concat": []string{"$lastName", " ", "$firstName"}}}
}},
)

If the specific field is double, convert it to Int [duplicate]

I am trying to change the type of a field from within the mongo shell.
I am doing this...
db.meta.update(
{'fields.properties.default': { $type : 1 }},
{'fields.properties.default': { $type : 2 }}
)
But it's not working!

The only way to change the $type of the data is to perform an update on the data where the data has the correct type.
In this case, it looks like you're trying to change the $type from 1 (double) to 2 (string).
So simply load the document from the DB, perform the cast (new String(x)) and then save the document again.
If you need to do this programmatically and entirely from the shell, you can use the find(...).forEach(function(x) {}) syntax.
In response to the second comment below. Change the field bad from a number to a string in collection foo.
db.foo.find( { 'bad' : { $type : 1 } } ).forEach( function (x) {
x.bad = new String(x.bad); // convert field to string
db.foo.save(x);
});

Convert String field to Integer:
db.db-name.find({field-name: {$exists: true}}).forEach(function(obj) {
obj.field-name = new NumberInt(obj.field-name);
db.db-name.save(obj);
});
Convert Integer field to String:
db.db-name.find({field-name: {$exists: true}}).forEach(function(obj) {
obj.field-name = "" + obj.field-name;
db.db-name.save(obj);
});

Starting Mongo 4.2, db.collection.update() can accept an aggregation pipeline, finally allowing the update of a field based on its own value:
// { a: "45", b: "x" }
// { a: 53, b: "y" }
db.collection.updateMany(
{ a : { $type: 1 } },
[{ $set: { a: { $toString: "$a" } } }]
)
// { a: "45", b: "x" }
// { a: "53", b: "y" }
The first part { a : { $type: 1 } } is the match query:
It filters which documents to update.
In this case, since we want to convert "a" to string when its value is a double, this matches elements for which "a" is of type 1 (double)).
This table provides the code representing the different possible types.
The second part [{ $set: { a: { $toString: "$a" } } }] is the update aggregation pipeline:
Note the squared brackets signifying that this update query uses an aggregation pipeline.
$set is a new aggregation operator (Mongo 4.2) which in this case modifies a field.
This can be simply read as "$set" the value of "a" to "$a" converted "$toString".
What's really new here, is being able in Mongo 4.2 to reference the document itself when updating it: the new value for "a" is based on the existing value of "$a".
Also note "$toString" which is a new aggregation operator introduced in Mongo 4.0.
In case your cast isn't from double to string, you have the choice between different conversion operators introduced in Mongo 4.0 such as $toBool, $toInt, ...
And if there isn't a dedicated converter for your targeted type, you can replace { $toString: "$a" } with a $convert operation: { $convert: { input: "$a", to: 2 } } where the value for to can be found in this table:
db.collection.updateMany(
{ a : { $type: 1 } },
[{ $set: { a: { $convert: { input: "$a", to: 2 } } } }]
)

For string to int conversion.
db.my_collection.find().forEach( function(obj) {
obj.my_value= new NumberInt(obj.my_value);
db.my_collection.save(obj);
});
For string to double conversion.
obj.my_value= parseInt(obj.my_value, 10);
For float:
obj.my_value= parseFloat(obj.my_value);

db.coll.find().forEach(function(data) {
db.coll.update({_id:data._id},{$set:{myfield:parseInt(data.myfield)}});
})

all answers so far use some version of forEach, iterating over all collection elements client-side.
However, you could use MongoDB's server-side processing by using aggregate pipeline and $out stage as :
the $out stage atomically replaces the existing collection with the
new results collection.
example:
db.documents.aggregate([
{
$project: {
_id: 1,
numberField: { $substr: ['$numberField', 0, -1] },
otherField: 1,
differentField: 1,
anotherfield: 1,
needolistAllFieldsHere: 1
},
},
{
$out: 'documents',
},
]);

To convert a field of string type to date field, you would need to iterate the cursor returned by the find() method using the forEach() method, within the loop convert the field to a Date object and then update the field using the $set operator.
Take advantage of using the Bulk API for bulk updates which offer better performance as you will be sending the operations to the server in batches of say 1000 which gives you a better performance as you are not sending every request to the server, just once in every 1000 requests.
The following demonstrates this approach, the first example uses the Bulk API available in MongoDB versions >= 2.6 and < 3.2. It updates all
the documents in the collection by changing all the created_at fields to date fields:
var bulk = db.collection.initializeUnorderedBulkOp(),
counter = 0;
db.collection.find({"created_at": {"$exists": true, "$type": 2 }}).forEach(function (doc) {
var newDate = new Date(doc.created_at);
bulk.find({ "_id": doc._id }).updateOne({
"$set": { "created_at": newDate}
});
counter++;
if (counter % 1000 == 0) {
bulk.execute(); // Execute per 1000 operations and re-initialize every 1000 update statements
bulk = db.collection.initializeUnorderedBulkOp();
}
})
// Clean up remaining operations in queue
if (counter % 1000 != 0) { bulk.execute(); }
The next example applies to the new MongoDB version 3.2 which has since deprecated the Bulk API and provided a newer set of apis using bulkWrite():
var bulkOps = [];
db.collection.find({"created_at": {"$exists": true, "$type": 2 }}).forEach(function (doc) {
var newDate = new Date(doc.created_at);
bulkOps.push(
{
"updateOne": {
"filter": { "_id": doc._id } ,
"update": { "$set": { "created_at": newDate } }
}
}
);
})
db.collection.bulkWrite(bulkOps, { "ordered": true });

To convert int32 to string in mongo without creating an array just add "" to your number :-)
db.foo.find( { 'mynum' : { $type : 16 } } ).forEach( function (x) {
x.mynum = x.mynum + ""; // convert int32 to string
db.foo.save(x);
});

What really helped me to change the type of the object in MondoDB was just this simple line, perhaps mentioned before here...:
db.Users.find({age: {$exists: true}}).forEach(function(obj) {
obj.age = new NumberInt(obj.age);
db.Users.save(obj);
});
Users are my collection and age is the object which had a string instead of an integer (int32).

You can easily convert the string data type to numerical data type.
Don't forget to change collectionName & FieldName.
for ex : CollectionNmae : Users & FieldName : Contactno.
Try this query..
db.collectionName.find().forEach( function (x) {
x.FieldName = parseInt(x.FieldName);
db.collectionName.save(x);
});

I need to change datatype of multiple fields in the collection, so I used the following to make multiple data type changes in the collection of documents. Answer to an old question but may be helpful for others.
db.mycoll.find().forEach(function(obj) {
if (obj.hasOwnProperty('phone')) {
obj.phone = "" + obj.phone; // int or longint to string
}
if (obj.hasOwnProperty('field-name')) {
obj.field-name = new NumberInt(obj.field-name); //string to integer
}
if (obj.hasOwnProperty('cdate')) {
obj.cdate = new ISODate(obj.cdate); //string to Date
}
db.mycoll.save(obj);
});

demo change type of field mid from string to mongo objectId using mongoose
Post.find({}, {mid: 1,_id:1}).exec(function (err, doc) {
doc.map((item, key) => {
Post.findByIdAndUpdate({_id:item._id},{$set:{mid: mongoose.Types.ObjectId(item.mid)}}).exec((err,res)=>{
if(err) throw err;
reply(res);
});
});
});
Mongo ObjectId is just another example of such styles as
Number, string, boolean that hope the answer will help someone else.

I use this script in mongodb console for string to float conversions...
db.documents.find({ 'fwtweaeeba' : {$exists : true}}).forEach( function(obj) {
obj.fwtweaeeba = parseFloat( obj.fwtweaeeba );
db.documents.save(obj); } );
db.documents.find({ 'versions.0.content.fwtweaeeba' : {$exists : true}}).forEach( function(obj) {
obj.versions[0].content.fwtweaeeba = parseFloat( obj.versions[0].content.fwtweaeeba );
db.documents.save(obj); } );
db.documents.find({ 'versions.1.content.fwtweaeeba' : {$exists : true}}).forEach( function(obj) {
obj.versions[1].content.fwtweaeeba = parseFloat( obj.versions[1].content.fwtweaeeba );
db.documents.save(obj); } );
db.documents.find({ 'versions.2.content.fwtweaeeba' : {$exists : true}}).forEach( function(obj) {
obj.versions[2].content.fwtweaeeba = parseFloat( obj.versions[2].content.fwtweaeeba );
db.documents.save(obj); } );
And this one in php)))
foreach($db->documents->find(array("type" => "chair")) as $document){
$db->documents->update(
array('_id' => $document[_id]),
array(
'$set' => array(
'versions.0.content.axdducvoxb' => (float)$document['versions'][0]['content']['axdducvoxb'],
'versions.1.content.axdducvoxb' => (float)$document['versions'][1]['content']['axdducvoxb'],
'versions.2.content.axdducvoxb' => (float)$document['versions'][2]['content']['axdducvoxb'],
'axdducvoxb' => (float)$document['axdducvoxb']
)
),
array('$multi' => true)
);
}

The above answers almost worked but had a few challenges-
Problem 1: db.collection.save no longer works in MongoDB 5.x
For this, I used replaceOne().
Problem 2: new String(x.bad) was giving exponential number
I used "" + x.bad as suggested above.
My version:
let count = 0;
db.user
.find({
custID: {$type: 1},
})
.forEach(function (record) {
count++;
const actualValue = record.custID;
record.custID = "" + record.custID;
console.log(`${count}. Updating User(id:${record._id}) from old id [${actualValue}](${typeof actualValue}) to [${record.custID}](${typeof record.custID})`)
db.user.replaceOne({_id: record._id}, record);
});
And for millions of records, here are the output (for future investigation/reference)-

Passing object to another variable

I'm trying to unit test the query function. When I debug with a breakpoint at the unit test below, I see that this.datasets = Object with the dataset info in my unit test. However, when I step into the query function, data is undefined. Why is it undefined and how do I set it to the dataset in my unit test?
QueryController.ts:
public query(query: QueryRequest): QueryResponse {
Log.trace('QueryController::query( ' + JSON.stringify(query) + ' )');
let data: any = this.datasets["courses"];
// do stuff
}
Unit test:
it("Valid query", function () {
let query: QueryRequest = {
// valid query code here
};
let dataset: Datasets = {
"234": {
"courses_dept": "math",
"courses_id": "327",
"courses_avg": 86.17,
"courses_instructor": "spears, britney",
"courses_title": "opera appreciation",
"courses_pass": 23,
"courses_fail": 10,
"courses_audit": 10
},
};
let controller = new QueryController(dataset);
let ret = controller.query(query);
//check stuff
});
Edit: I fixed the problem. query() was calling this.datasets["courses"]. I needed to add a "courses" key to my dataset in the unit test.

How to access data returned by group reduce in Mongo?

I have a JavaScript file as
var x = new Mongo('127.0.0.1:27017');
var db = x.getDB('user');
var r = db.runCommand({"group" : {
"ns" : "track_user", "key" : {userId : 1}, "initial" : {
count:0 }, cond: {
uri: {
$regex: 'sm'
} }, "$reduce" : function(doc, prev) {
} } } }});
while(r.hasNext()){
rs = r.next();
}
I am not able to run through results returned by group reduce.
output of group reduce run via shell is something like
{
"retval" : [
{
"userId" : 0,
"created" : "2013-08-08 11:32:15",
"uri" : "abc.com",
"uri_set" : [
"xyz.com"
]
},...
],
"count" : 14,
"keys" : 6,
"ok" : 1
}
hasNext is giving error as
Sat Nov 23 00:53:40.351 JavaScript execution failed: TypeError: Object [object Object] has no method 'hasNext' at /var/www/admin/app/controllers/newjavascript1.js:L62

The problem is that db.runCommand() does not return a cursor, so none of the cursor methods are going to work on it. You're returning a document with the results nested inside, so you're going to have to work with the data a different way.
You should be able to either use map or each, depending on what you're trying to do:
var mySet = r.retval;
mySet.forEach( function(doc) {
console.log( doc );
});
Or, whatever you need it to do.