I have a document with an array field, similar to this:
{
"_id" : "....",
"Statuses" : [
{ "Type" : 1, "Timestamp" : ISODate(...) },
{ "Type" : 2, "Timestamp" : ISODate(...) },
//Etc. etc.
]
}
How can I update a specific Status item's Timestamp, by specifying its Type value?
From mongodb shell you can do this by
db.your_collection.update(
{ _id: ObjectId("your_objectid"), "Statuses.Type": 1 },
{ $set: { "Statuses.$.Timestamp": "new timestamp" } }
)
so the c# equivalent
var query = Query.And(
Query.EQ("_id", "your_doc_id"),
Query.EQ("Statuses.Type", 1)
);
var result = your_collection.Update(
query,
Update.Set("Statuses.$.Timestamp", "new timestamp", UpdateFlags.Multi,SafeMode.True)
);
This will update the specific document, you can remove _id filter if you wanted to update the whole collection
Starting with MongoDB 3.6, the $[<identifier>] positional operator may be used. Unlike the $ positional operator — which updates at most one array element per document — the $[<identifier>] operator will update every matching array element. This is useful for scenarios where a given document may have multiple matching array elements that need to be updated.
db.yourCollection.update(
{ _id: "...." },
{ $set: {"Statuses.$[element].Timestamp": ISODate("2021-06-23T03:47:18.548Z")} },
{ arrayFilters: [{"element.Type": 1}] }
);
The arrayFilters option matches the array elements to update, and the $[element] is used within the $set update operator to indicate that only array elements that matched the arrayFilter should be updated.
Related
I have a large amount of data (~160M items) where a date value wasn't populated on the sub-document array fields, but was populated on the parent document. I'm very new to MongoDB and having trouble figuring out how to $set the field to match. Here's a sample of the data:
{
"_id": "5f11d4c48663f32e940696ed",
"Widgets":[{
"WidgetId":663,
"Name":"Super Widget 2.0",
"Created":null,
"LastUpdated":null
}],
"Status":3,
"LastUpdated":null,
"Created": "2018-11-09T18:22:16.000Z"
}
}
My knowledge of MongoDB is pretty limited but here's the basic aggregation I have created for part of the pipeline and where I'm struggling:
db.sample.aggregate(
[
{
"$match" : {
"Donors.$.Created" : {
"$exists" : true
}
}
},
{
"$match" : {
"Widgets.$.Created" : null
}
},
{
"$set" : {
"Widgets.$.Created" : "Created" // <- This is where I can't figure out how to define the reference to the parent "Created" field
}
}
]
);
The desired output would be:
{
"_id": "5f11d4c48663f32e940696ed",
"Widgets":[{
"WidgetId":663,
"Name":"Super Widget 2.0",
"Created":"2018-11-09T18:22:16.000Z",
"LastUpdated":null
}],
"Status":3,
"LastUpdated":null,
"Created": "2018-11-09T18:22:16.000Z"
}
}
Thanks for any assitance
Are you attempting to add the Created field to sub documents on query/aggregation? Or are you attempting to update/save the Created field on the subdocuments?
The $ is an update operator, to be used with updateMany or updateOne. Not aggregate.
https://docs.mongodb.com/manual/reference/operator/query-array/
https://docs.mongodb.com/manual/reference/operator/update-array/
If you just want to add the parents Created field to all subdocuments on query/aggregation this is all you have to do: https://mongoplayground.net/p/yHDHULCSTIz
db.collection.aggregate([
{
"$addFields": {
"Widgets.Created": "$Created"
}
}
])
If your attempting to save the parents Created field to all subdocuments:
db.sample.updateMany({"Widgets.Created" : null}, [{$set: {"Widgets.Created" : "$Created"}}])
Note: This matches any doc that has a subdocument with a null Created field and updates all the subdocuments.
I have a collection of documents where a "tags" field was switched over from being a space separated list of tags to an array of individual tags. I want to update the previous space-separated fields to all be arrays like the new incoming data.
I'm also having problems with the $type selector because it is applying the type operation to individual array elements, which are strings. So filtering by type just returns everything.
How can I get every document that looks like the first example into the format for the second example?
{
"_id" : ObjectId("12345"),
"tags" : "red blue green white"
}
{
"_id" : ObjectId("54321"),
"tags" : [
"red",
"orange",
"black"
]
}
We can't use the $type operator to filter our documents here because the type of the elements in our array is "string" and as mentioned in the documentation:
When applied to arrays, $type matches any inner element that is of the specified BSON type. For example, when matching for $type : 'array', the document will match if the field has a nested array. It will not return results where the field itself is an array.
But fortunately MongoDB also provides the $exists operator which can be used here with a numeric array index.
Now how can we update those documents?
Well, from MongoDB version <= 3.2, the only option we have is mapReduce() but first let look at the other alternative in the upcoming release of MongoDB.
Starting from MongoDB 3.4, we can $project our documents and use the $split operator to split our string into an array of substrings.
Note that to split only those "tags" which are string, we need a logical $condition processing to split only the values that are string. The condition here is $eq which evaluate to true when the $type of the field is equal to "string". By the way $type here is new in 3.4.
Finally we can overwrite the old collection using the $out pipeline stage operator. But we need to explicitly specify the inclusion of other field in the $project stage.
db.collection.aggregate(
[
{ "$project": {
"tags": {
"$cond": [
{ "$eq": [
{ "$type": "$tags" },
"string"
]},
{ "$split": [ "$tags", " " ] },
"$tags"
]
}
}},
{ "$out": "collection" }
]
)
With mapReduce, we need to use the Array.prototype.split() to emit the array of substrings in our map function. We also need to filter our documents using the "query" option. From there we will need to iterate the "results" array and $set the new value for "tags" using bulk operations using the bulkWrite() method new in 3.2 or the now deprecated Bulk() if we are on 2.6 or 3.0 as shown here.
db.collection.mapReduce(
function() { emit(this._id, this.tags.split(" ")); },
function(key, value) {},
{
"out": { "inline": 1 },
"query": {
"tags.0": { "$exists": false },
"tags": { "$type": 2 }
}
}
)['results']
I would like to add a document if it does not exist and else add an element to one of it's sub-documents.
db.test.update(
{
name : 'Peter'
},
$setOnInsert : {
name : 'Peter',
visits: { 'en' : ['today'], 'us' : [] }
},
$push : {
visits.en : 'today'
},
{ upsert : true }
)
If Peter exists, add an element to its visists.en or visists.us arrays. Else, create a document for Peter. This document should have the format for visits which should contain the current element ('today').
My issue is that I have "have conflicting mods in update".
I.e. (afaik), I cannot write to two things in one query. Yet how can I solve this dilemma?
You could implement it without $setOnInsert operator.
db.test.update(
{
name : 'Peter'
},
{
$push : {
"visits.en" : 'today'
}
},
{ upsert : true }
)
If Peter exists, element 'today' will be added to its visits.en array. Else, will be created a document for Peter, with visits object, that will be contain array en with 'today' element.
And I think, that error occured because of you using same property (visits) in two operations ($setOnInsert and $push).
You can still use $setOnInsert but when $setOnInsert and $push doesn't updates in the same fields as mentioned before.
N.b: We use $addToSet if you don't want a duplicated values in your Array
db.test.update(
{
name : 'Peter'
},
{
$setOnInsert: {name : 'Peter'},
$addToSet: {"visits.en": 'today'} // or $push
},
{upsert: true})
I have a document with an array field, similar to this:
{
"_id" : "....",
"Statuses" : [
{ "Type" : 1, "Timestamp" : ISODate(...) },
{ "Type" : 2, "Timestamp" : ISODate(...) },
//Etc. etc.
]
}
How can I update a specific Status item's Timestamp, by specifying its Type value?
From mongodb shell you can do this by
db.your_collection.update(
{ _id: ObjectId("your_objectid"), "Statuses.Type": 1 },
{ $set: { "Statuses.$.Timestamp": "new timestamp" } }
)
so the c# equivalent
var query = Query.And(
Query.EQ("_id", "your_doc_id"),
Query.EQ("Statuses.Type", 1)
);
var result = your_collection.Update(
query,
Update.Set("Statuses.$.Timestamp", "new timestamp", UpdateFlags.Multi,SafeMode.True)
);
This will update the specific document, you can remove _id filter if you wanted to update the whole collection
Starting with MongoDB 3.6, the $[<identifier>] positional operator may be used. Unlike the $ positional operator — which updates at most one array element per document — the $[<identifier>] operator will update every matching array element. This is useful for scenarios where a given document may have multiple matching array elements that need to be updated.
db.yourCollection.update(
{ _id: "...." },
{ $set: {"Statuses.$[element].Timestamp": ISODate("2021-06-23T03:47:18.548Z")} },
{ arrayFilters: [{"element.Type": 1}] }
);
The arrayFilters option matches the array elements to update, and the $[element] is used within the $set update operator to indicate that only array elements that matched the arrayFilter should be updated.
In the following example, assume the document is in the db.people collection.
How to remove the 3rd element of the interests array by it's index?
{
"_id" : ObjectId("4d1cb5de451600000000497a"),
"name" : "dannie",
"interests" : [
"guitar",
"programming",
"gadgets",
"reading"
]
}
This is my current solution:
var interests = db.people.findOne({"name":"dannie"}).interests;
interests.splice(2,1)
db.people.update({"name":"dannie"}, {"$set" : {"interests" : interests}});
Is there a more direct way?
There is no straight way of pulling/removing by array index. In fact, this is an open issue http://jira.mongodb.org/browse/SERVER-1014 , you may vote for it.
The workaround is using $unset and then $pull:
db.lists.update({}, {$unset : {"interests.3" : 1 }})
db.lists.update({}, {$pull : {"interests" : null}})
Update: as mentioned in some of the comments this approach is not atomic and can cause some race conditions if other clients read and/or write between the two operations. If we need the operation to be atomic, we could:
Read the document from the database
Update the document and remove the item in the array
Replace the document in the database. To ensure the document has not changed since we read it, we can use the update if current pattern described in the mongo docs
You can use $pull modifier of update operation for removing a particular element in an array. In case you provided a query will look like this:
db.people.update({"name":"dannie"}, {'$pull': {"interests": "guitar"}})
Also, you may consider using $pullAll for removing all occurrences. More about this on the official documentation page - http://www.mongodb.org/display/DOCS/Updating#Updating-%24pull
This doesn't use index as a criteria for removing an element, but still might help in cases similar to yours. IMO, using indexes for addressing elements inside an array is not very reliable since mongodb isn't consistent on an elements order as fas as I know.
in Mongodb 4.2 you can do this:
db.example.update({}, [
{$set: {field: {
$concatArrays: [
{$slice: ["$field", P]},
{$slice: ["$field", {$add: [1, P]}, {$size: "$field"}]}
]
}}}
]);
P is the index of element you want to remove from array.
If you want to remove from P till end:
db.example.update({}, [
{ $set: { field: { $slice: ["$field", 1] } } },
]);
Starting in Mongo 4.4, the $function aggregation operator allows applying a custom javascript function to implement behaviour not supported by the MongoDB Query Language.
For instance, in order to update an array by removing an element at a given index:
// { "name": "dannie", "interests": ["guitar", "programming", "gadgets", "reading"] }
db.collection.update(
{ "name": "dannie" },
[{ $set:
{ "interests":
{ $function: {
body: function(interests) { interests.splice(2, 1); return interests; },
args: ["$interests"],
lang: "js"
}}
}
}]
)
// { "name": "dannie", "interests": ["guitar", "programming", "reading"] }
$function takes 3 parameters:
body, which is the function to apply, whose parameter is the array to modify. The function here simply consists in using splice to remove 1 element at index 2.
args, which contains the fields from the record that the body function takes as parameter. In our case "$interests".
lang, which is the language in which the body function is written. Only js is currently available.
Rather than using the unset (as in the accepted answer), I solve this by setting the field to a unique value (i.e. not NULL) and then immediately pulling that value. A little safer from an asynch perspective. Here is the code:
var update = {};
var key = "ToBePulled_"+ new Date().toString();
update['feedback.'+index] = key;
Venues.update(venueId, {$set: update});
return Venues.update(venueId, {$pull: {feedback: key}});
Hopefully mongo will address this, perhaps by extending the $position modifier to support $pull as well as $push.
I would recommend using a GUID (I tend to use ObjectID) field, or an auto-incrementing field for each sub-document in the array.
With this GUID it is easy to issue a $pull and be sure that the correct one will be pulled. Same goes for other array operations.
For people who are searching an answer using mongoose with nodejs. This is how I do it.
exports.deletePregunta = function (req, res) {
let codTest = req.params.tCodigo;
let indexPregunta = req.body.pregunta; // the index that come from frontend
let inPregunta = `tPreguntas.0.pregunta.${indexPregunta}`; // my field in my db
let inOpciones = `tPreguntas.0.opciones.${indexPregunta}`; // my other field in my db
let inTipo = `tPreguntas.0.tipo.${indexPregunta}`; // my other field in my db
Test.findOneAndUpdate({ tCodigo: codTest },
{
'$unset': {
[inPregunta]: 1, // put the field with []
[inOpciones]: 1,
[inTipo]: 1
}
}).then(()=>{
Test.findOneAndUpdate({ tCodigo: codTest }, {
'$pull': {
'tPreguntas.0.pregunta': null,
'tPreguntas.0.opciones': null,
'tPreguntas.0.tipo': null
}
}).then(testModificado => {
if (!testModificado) {
res.status(404).send({ accion: 'deletePregunta', message: 'No se ha podido borrar esa pregunta ' });
} else {
res.status(200).send({ accion: 'deletePregunta', message: 'Pregunta borrada correctamente' });
}
})}).catch(err => { res.status(500).send({ accion: 'deletePregunta', message: 'error en la base de datos ' + err }); });
}
I can rewrite this answer if it dont understand very well, but I think is okay.
Hope this help you, I lost a lot of time facing this issue.
It is little bit late but some may find it useful who are using robo3t-
db.getCollection('people').update(
{"name":"dannie"},
{ $pull:
{
interests: "guitar" // you can change value to
}
},
{ multi: true }
);
If you have values something like -
property: [
{
"key" : "key1",
"value" : "value 1"
},
{
"key" : "key2",
"value" : "value 2"
},
{
"key" : "key3",
"value" : "value 3"
}
]
and you want to delete a record where the key is key3 then you can use something -
db.getCollection('people').update(
{"name":"dannie"},
{ $pull:
{
property: { key: "key3"} // you can change value to
}
},
{ multi: true }
);
The same goes for the nested property.
this can be done using $pop operator,
db.getCollection('collection_name').updateOne( {}, {$pop: {"path_to_array_object":1}})