I'm still new to MongoDB, in an aggregate query I'm trying to use a value from a field as the key to getting the other value. For example in the following document,
{
"_id" : ObjectId("5d9c245bb6c0ac7a34a43bf5"),
"status" : {
"code" : "ES004",
"params" : {
"star" : "VSP"
}
},
"description" : "{star} has been added to the cast/crew officially",
"stringToReplace" : "{star}",
"valueToReplace" : "status.params.star"
}
I wanted to replace the value of stringToReplace in description with the value of valueToReplace (i.e., value in status.params.star which is VSP)
Is there any way of doing this in an aggregate query or only way to go with this is Mongo shell?
Related
I have this very basic collection (blog.posts) from which I want to update the value of a key (author.name) using the $set modifier. Here is a sample of a document from the collection:
{
"_id" : ObjectId("5ca66e7d8a3bb6e58e0d85f4"),
"s_id": "unique_post",
"title" : "MongoDB is cool",
"author.name" : "Terence"
}
I want to change the value of the author.name key from Terence to Benjamin and this is the query with which I'm trying to acheive the result:
db.blog.posts.update({"s_id": "unique_post"}, {"$set":{"author.name":"Benjamin"}})
The issue is that when I execute this query, I end up with a new nested ducument as shown:
{
"_id" : ObjectId("5ca66e7d8a3bb6e58e0d85f4"),
"title" : "MongoDB is cool",
"author.name" : "Terence",
"author" : {
"name" : "Benjamin"
}
}
I know that this is to be expected but my question is: How do I modify a value in a document who's key contains a dot(.) ?
Please I'm new to mongoDB and any other tips would be highly appreciated.
As per MongoDB documentation dot(.) is a restricted character in field names. So you cannot have dot(.) in field names. That is the reason it converts the dot(.) value into subdocument.
I have MongoDB Collection where some documents have arrays of objects. One of the fields of this objects is timestamp.
The problem is that historically some of timestamp values are Strings (e.g. '2018-02-25T13:33:56.675000') or Date and some of them are Double (e.g. 1528108521726.26).
I have to convert all of them to Double.
I've built the query to get all the documents with the problematic type:
db.getCollection('Cases').find({sent_messages: {$elemMatch:{timestamp: {$type:[2, 9]}}}})
And I also know how to convert Date-string to double using JS:
new Date("2018-02-18T06:39:20.797Z").getTime()
> 1518935960797
But I can't build the proper query to perform the update.
Here is an example of such a document:
{
"_id" : ObjectId("6c88f656532aab00050dc023"),
"created_at" : ISODate("2018-05-18T03:43:18.986Z"),
"updated_at" : ISODate("2018-05-18T06:39:20.798Z"),
"sent_messages" : [
{
"timestamp" : ISODate("2018-02-18T06:39:20.797Z"),
"text" : "Hey",
"sender" : "me"
}
],
"status" : 1
}
After the update it should be:
{
"_id" : ObjectId("6c88f656532aab00050dc023"),
"created_at" : ISODate("2018-05-18T03:43:18.986Z"),
"updated_at" : ISODate("2018-05-18T06:39:20.798Z"),
"sent_messages" : [
{
"timestamp" : 1518935960797.00,
"text" : "Hey",
"sender" : "me"
}
],
"status" : 1
}
As per your question, you are trying to fetch the record first.
db.getCollection('Cases').find({sent_messages: {$elemMatch:{timestamp: {$type:[2, 9]}}}})
Then convert date in JS:
new Date("2018-02-18T06:39:20.797Z").getTime()
And then this is an update query:
db.getCollection('Cases').updateOne({_id:ObjectId("6c88f656532aab00050dc023")}, { $set: { "sent_messages.$.timestamp" : "218392712937.0" }})
And if you want to update all records then you should write some forEach mechanism. I think you have already this implemented.
Hope this may help you.
Finally I just do it with JS code that can be run in mongo console:
db.getCollection('Cases').find({sent_messages: {$elemMatch:{timestamp: {$type:[2, 9]}}}}).forEach(function(doc) {
print('=================');
print(JSON.stringify(doc));
doc.sent_messages.forEach(function(msg){
var dbl = new Date(msg.timestamp).getTime();
print(dbl);
msg.timestamp = dbl;
});
print(JSON.stringify(doc))
db.Cases.save(doc);
} )
Thanks all for your help!
how can I return a specific value for a specific document in MongoDB? For example, I have a schema that looks like:
{
"_id" : "XfCZSje7GjynvMZu7",
"createdAt" : ISODate("2015-03-23T14:52:44.084Z"),
"services" : {
"password" : {
"bcrypt" : "$2a$10$tcb01VbDMVhH03mbRdKYL.79FPj/fFMP62BDpcvpoTfF3LPgjHJoq"
},
"resume" : {
"loginTokens" : [ ]
}
},
"emails" : {
"address" : "abc123#gmu.edu",
"verified" : true
},
"profile" : {
"companyName" : "comp1",
"flagged" : true,
"phoneNum" : "7778883333"
}}
I want to return and store the value for profile.flagged specifically for the document with _id : XfCZSje7GjynvMZu7. So far I have tried:
db.users.find({_id:'myfi3E4YTf9z6tdgS'},{admin:1})
and
db.users.find({_id: 'myfi3E4YTf9z6tdgS'}, {profile:admin});
I want the query to return true or false depending on the assigned value.
Can someone help? Thanks!
MongoDB queries always return document objects, not single values. So one way to do this is with shell code like:
var flagged =
db.users.findOne({_id: 'myfi3E4YTf9z6tdgS'}, {'profile.flagged': 1}).profile.flagged;
Note the use of findOne instead of find so that you're working with just a single doc instead of the cursor that you get with find.
The correct answer here is the method .distinct() (link here)
Use it like this:
db.users.find({_id:'myfi3E4YTf9z6tdgS'},{admin:1}).distinct('admin')
The result will be: 1 or 0
My MongoDB collection is made up of 2 main collections :
1) Maps
{
"_id" : ObjectId("542489232436657966204394"),
"fileName" : "importFile1.json",
"territories" : [
{
"$ref" : "territories",
"$id" : ObjectId("5424892224366579662042e9")
},
{
"$ref" : "territories",
"$id" : ObjectId("5424892224366579662042ea")
}
]
},
{
"_id" : ObjectId("542489262436657966204398"),
"fileName" : "importFile2.json",
"territories" : [
{
"$ref" : "territories",
"$id" : ObjectId("542489232436657966204395")
}
],
"uploadDate" : ISODate("2012-08-22T09:06:40.000Z")
}
2) Territories, which are referenced in "Map" objects :
{
"_id" : ObjectId("5424892224366579662042e9"),
"name" : "Afghanistan",
"area" : 653958
},
{
"_id" : ObjectId("5424892224366579662042ea"),
"name" : "Angola",
"area" : 1252651
},
{
"_id" : ObjectId("542489232436657966204395"),
"name" : "Unknown",
"area" : 0
}
My objective is to list every map with their cumulative area and number of territories. I am trying the following query :
db.maps.aggregate(
{'$unwind':'$territories'},
{'$group':{
'_id':'$fileName',
'numberOf': {'$sum': '$territories.name'},
'locatedArea':{'$sum':'$territories.area'}
}
})
However the results show 0 for each of these values :
{
"result" : [
{
"_id" : "importFile2.json",
"numberOf" : 0,
"locatedArea" : 0
},
{
"_id" : "importFile1.json",
"numberOf" : 0,
"locatedArea" : 0
}
],
"ok" : 1
}
I probably did something wrong when trying to access to the member variables of Territory (name and area), but I couldn't find an example of such a case in the Mongo doc. area is stored as an integer, and name as a string.
I probably did something wrong when trying to access to the member variables of Territory (name and area), but I couldn't find an example
of such a case in the Mongo doc. area is stored as an integer, and
name as a string.
Yes indeed, the field "territories" has an array of database references and not the actual documents. DBRefs are objects that contain information with which we can locate the actual documents.
In the above example, you can clearly see this, fire the below mongo query:
db.maps.find({"_id":ObjectId("542489232436657966204394")}).forEach(function(do
c){print(doc.territories[0]);})
it will print the DBRef object rather than the document itself:
o/p: DBRef("territories", ObjectId("5424892224366579662042e9"))
so, '$sum': '$territories.name','$sum': '$territories.area' would show you '0' since there are no fields such as name or area.
So you need to resolve this reference to a document before doing something like $territories.name
To achieve what you want, you can make use of the map() function, since aggregation nor Map-reduce support sub queries, and you already have a self-contained map document, with references to its territories.
Steps to achieve:
a) get each map
b) resolve the `DBRef`.
c) calculate the total area, and the number of territories.
d) make and return the desired structure.
Mongo shell script:
db.maps.find().map(function(doc) {
var territory_refs = doc.territories.map(function(terr_ref) {
refName = terr_ref.$ref;
return terr_ref.$id;
});
var areaSum = 0;
db.refName.find({
"_id" : {
$in : territory_refs
}
}).forEach(function(i) {
areaSum += i.area;
});
return {
"id" : doc.fileName,
"noOfTerritories" : territory_refs.length,
"areaSum" : areaSum
};
})
o/p:
[
{
"id" : "importFile1.json",
"noOfTerritories" : 2,
"areaSum" : 1906609
},
{
"id" : "importFile2.json",
"noOfTerritories" : 1,
"areaSum" : 0
}
]
Map-Reduce functions should not be and cannot be used to resolve DBRefs in the server side.
See what the documentation has to say:
The map function should not access the database for any reason.
The map function should be pure, or have no impact outside of the
function (i.e. side effects.)
The reduce function should not access the database, even to perform
read operations. The reduce function should not affect the outside
system.
Moreover, a reduce function even if used(which can never work anyway) will never be called for your problem, since a group w.r.t "fileName" or "ObjectId" would always have only one document, in your dataset.
MongoDB will not call the reduce function for a key that has only a
single value
With a schema like this, where the "items" field contains an array of subdocuments with nested translations :
{
"_id" : ObjectId("513740415b51ea0803000001"),
"items" : [
{
"id" : ObjectId("5137407f5b51ea100f000000"),
"title" : {
"en" : "Yes",
"fr" : "Oui",
"es" : "Si"
}
},
{
"id" : ObjectId("5137407f5b51ea100f000003"),
"title" : {
"en" : "No"
}
}
],
}
How would you add a translation to a specific item id ?
You can use the $ positional operator to update a specific array element of a doc.
For example, to add "de": "nein":
db.test.update(
{'items.id': ObjectId("5137407f5b51ea100f000003")},
{$set: {'items.$.title.de': 'nein'}})
The $ in the $set object represents the index of the element in items that the query selection parameter matched.
You can do it like that:
db.yourColName.update({"items.id" : "itemId"}, {$set : {"translationField" : "translationValue"}})
Over here in the first part of the query you are searching for the direct item in the array and set a new field + value for it.
The thing is, like you have already noticed, that Mongo doesn't have static schema. So $set will either update already existing field or create a new one. It all depends on the field name you set in the subquery.
To get to the direct document use the $ operator: items.$.title.fr where $ would represent the current object.