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"}}}
}},
)
Related
Hi I have json structure #1 and #2 as follows. I would like to compare and capture the results.
Json #1.
{
"menu": {
"id": "file",
"popup": {
"menuitem": {
"menuitem-1": "sometext",
"menuitem-2": {
"menuitem-2.1": "sometext",
"menuitem-2.2": "sometext",
"menuitem-2.3": {
"menuitem-2.3.1": "sometext"
}
}
}
},
"value": "File"
}
}
Json #2
{
"menu": {
"id": "file",
"popup": {
"menuitem": {
"menuitem-2.3": {
"menuitem-2.3.1": "sometext"
}
"menuitem-1": "sometext",
"menuitem-2": {
"menuitem-2.1": "sometext",
"menuitem-2.2": "sometext"
},
}
},
"value": "File"
}
}
Am expecting that below JSON has been moved up in JSON #2. My goal here is identify any CREATE NEW / UPDATE / ADJUSTED / DELETE on JSON#2.
"menuitem-2.3": {
"menuitem-2.3.1": "sometext"
}
Is there any Spring / Java existing framework available to achieve above?
Use difference from org.apache.commons.lang.StringUtils.
Compares two Strings, and returns the portion where they differ. (More precisely, return the remainder of the second String, starting from where it's different from the first.)
For example,
difference("i am a machine", "i am a robot") -> "robot".
StringUtils.difference(null, null) = null
StringUtils.difference("", "") = ""
StringUtils.difference("", "abc") = "abc"
StringUtils.difference("abc", "") = ""
StringUtils.difference("abc", "abc") = ""
StringUtils.difference("ab", "abxyz") = "xyz"
StringUtils.difference("abcde", "abxyz") = "xyz"
StringUtils.difference("abcde", "xyz") = "xyz"
Parameters:
str1 - the first String, may be null
str2 - the second String, may be null
Try using Apache drill. It is easy to install and supports querying JSON. You can then execute a minus query and get the difference.
You can also query drill using java. Apache drill has a JDBC driver for that.
Hope it helps. :)
In MongoDB Java driver how to use the "explain" option ?
db.orders.aggregate([
{ $match: { status: "A" } },
{ $sort: { total: -1 } }
],
{ explain: true }
)
Collection.aggregate() does not accept options
orders.aggregate(Arrays.asList(
Aggregates.match(Filters.eq("status","A")),
Aggregates.sort(Sorts.descending("total"))
))
You can fall back to runCommand and use the explain command that way.
Something along the lines of
db.runCommand(new Document(myMap))
where myMap is (writing in JSON)
{"explain": {"aggregate": "my.collection", "pipeline": [{"$project": {"_id": 1}}]}}
I'm using mongodb version 3.4, with java driver.
I have a collection of jsons of this format:
{
"foo": {
"d4231ds": {
"type":"A",
"color":"red"
},
"dmncxa3s": {
"type":"B",
"color":"yellow"
},
"JsdjS8": {
"type":"A",
"color":"red"
},
"SKJDcxar3": {
"type":"C",
"color":"green"
}
},
"bar": "100011"
}
I need to get all the documents which have "type":"A", using java. The keys under foo (d4231ds,dmncxa3s etc) aren't known in advance, and differ between the documents. Hence, using the dot operator is not working in this case.
I've tried looking on several methods, but non seemed to achieve this.
You can try the below aggregation in latest 3.4 server version.
Use $objectToArray to convert the named keys into key value pair ( k, v ) and use $in to query the value document for field type = A.
$redact which acts on the results from query filter, $$KEEP when match else $$PRUNE
MongoClient mongoClient = new MongoClient();
MongoDatabase database = mongoClient.getDatabase(db_name);
MongoCollection<Document> mongoCollection = database.getCollection(collection_name);
Document query = Document.parse("{\"$redact\":{\"$cond\":[{\"$let\":{\"vars\":{\"subelems\":{\"$objectToArray\":\"$foo\"}},\"in\":{\"$in\":[\"A\",\"$$subelems.v.type\"]}}},\"$$KEEP\",\"$$PRUNE\"]}}");
List<Document> result = mongoCollection.aggregate(Arrays.asList(query)).into(new ArrayList<>());
Mongo Shell Query:
db.collection_name.aggregate([
{
"$redact": {
"$cond": [
{
"$let": {
"vars": {
"subelems": {
"$objectToArray": "$foo"
}
},
"in": {
"$in": [
"A",
"$$subelems.v.type"
]
}
}
},
"$$KEEP",
"$$PRUNE"
]
}
}
])
I am looking for a solution without spring data. My project requirement is to do without spring data.
To calculate the sum using aggregate function by mongo command, able to get output. But same by using spring data getting exception.
Sample mongo query :
db.getCollection('events_collection').aggregate(
{ "$match" : { "store_no" : 3201 , "event_id" : 882800} },
{ "$group" : { "_id" : "$load_dt", "event_id": { "$first" : "$event_id" }, "start_dt" : { "$first" : "$start_dt" }, "count" : { "$sum" : 1 } } },
{ "$sort" : { "_id" : 1 } },
{ "$project" : { "load_dt" : "$_id", "ksn_cnt" : "$count", "event_id" : 1, "start_dt" : 1, "_id" : 0 } }
)
Same thing done in java as,
String json = "[ { \"$match\": { \"store_no\": 3201, \"event_id\": 882800 } }, { \"$group\": { \"_id\": \"$load_dt\", \"event_id\": { \"$first\": \"$event_id\" }, \"start_dt\": { \"$first\": \"$start_dt\" }, \"count\": { \"$sum\": 1 } } }, { \"$sort\": { \"_id\": 1 } }, { \"$project\": { \"load_dt\": \"$_id\", \"ksn_cnt\": \"$count\", \"event_id\": 1, \"start_dt\": 1, \"_id\": 0 } } ]";
BasicDBList pipeline = (BasicDBList) JSON.parse(json);
System.out.println(pipeline);
AggregationOutput output = col.aggregate(pipeline);
exception is :
com.mongodb.CommandFailureException: { "serverUsed" : "somrandomserver/10.10.10.10:27001" , "errmsg" : "exception: pipeline element 0 is not an object" , "code" : 15942 , "ok" : 0.0}
Could someone please suggest how to use aggregate function with spring?
Try the following (untested) Spring Data MongoDB aggregation equivalent
import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
MongoTemplate mongoTemplate = repository.getMongoTemplate();
Aggregation agg = newAggregation(
match(Criteria.where("store_no").is(3201).and("event_id").is(882800)),
group("load_dt")
.first("event_id").as("event_id")
.first("start_dt").as("start_dt")
.count().as("ksn_cnt"),
sort(ASC, previousOperation()),
project("ksn_cnt", "event_id", "start_dt")
.and("load_dt").previousOperation()
.and(previousOperation()).exclude()
);
AggregationResults<OutputType> result = mongoTemplate.aggregate(agg,
"events_collection", OutputType.class);
List<OutputType> mappedResult = result.getMappedResults();
As a first step, filter the input collection by using a match operation which accepts a Criteria query as an argument.
In the second step, group the intermediate filtered documents by the "load_dt" field and calculate the document count and store the result in the new field "ksn_cnt".
Sort the intermediate result by the id-reference of the previous group operation as given by the previousOperation() method.
Finally in the fourth step, select the "ksn_cnt", "event_id", and "start_dt" fields from the previous group operation. Note that "load_dt" again implicitly references an group-id field. Since you do not want an implicit generated id to appear, exclude the id from the previous operation via and(previousOperation()).exclude().
Note that if you provide an input class as the first parameter to the newAggregation method the MongoTemplate will derive the name of the input collection from this class. Otherwise if you don’t not specify an input class you must provide the name of the input collection explicitly. If an input-class and an input-collection is provided the latter takes precedence.
How can I sort a MongoDB collection by a given field, case-insensitively? By default, I get A-Z before a-z.
Update:
As of now mongodb have case insensitive indexes:
Users.find({})
.collation({locale: "en" })
.sort({name: 1})
.exec()
.then(...)
shell:
db.getCollection('users')
.find({})
.collation({'locale':'en'})
.sort({'firstName':1})
Update: This answer is out of date, 3.4 will have case insensitive indexes. Look to the JIRA for more information https://jira.mongodb.org/browse/SERVER-90
Unfortunately MongoDB does not yet have case insensitive indexes: https://jira.mongodb.org/browse/SERVER-90 and the task has been pushed back.
This means the only way to sort case insensitive currently is to actually create a specific "lower cased" field, copying the value (lower cased of course) of the sort field in question and sorting on that instead.
Sorting does work like that in MongoDB but you can do this on the fly with aggregate:
Take the following data:
{ "field" : "BBB" }
{ "field" : "aaa" }
{ "field" : "AAA" }
So with the following statement:
db.collection.aggregate([
{ "$project": {
"field": 1,
"insensitive": { "$toLower": "$field" }
}},
{ "$sort": { "insensitive": 1 } }
])
Would produce results like:
{
"field" : "aaa",
"insensitive" : "aaa"
},
{
"field" : "AAA",
"insensitive" : "aaa"
},
{
"field" : "BBB",
"insensitive" : "bbb"
}
The actual order of insertion would be maintained for any values resulting in the same key when converted.
This has been an issue for quite a long time on MongoDB JIRA, but it is solved now. Take a look at this release notes for detailed documentation. You should use collation.
User.find()
.collation({locale: "en" }) //or whatever collation you want
.sort({name:1})
.exec(function(err, users) {
// use your case insensitive sorted results
});
Adding the code .collation({'locale':'en'}) helped to solve my issue.
As of now (mongodb 4), you can do the following:
mongo shell:
db.getCollection('users')
.find({})
.collation({'locale':'en'})
.sort({'firstName':1});
mongoose:
Users.find({})
.collation({locale: "en" })
.sort({name: 1})
.exec()
.then(...)
Here are supported languages and locales by mongodb.
In Mongoose:-
Customer.find()
.collation({locale: "en" })
.sort({comapany: 1})
Here it is in Java. I mixed no-args and first key-val variants of BasicDBObject just for variety
DBCollection coll = db.getCollection("foo");
List<DBObject> pipe = new ArrayList<DBObject>();
DBObject prjflds = new BasicDBObject();
prjflds.put("field", 1);
prjflds.put("insensitive", new BasicDBObject("$toLower", "$field"));
DBObject project = new BasicDBObject();
project.put("$project", prjflds);
pipe.add(project);
DBObject sort = new BasicDBObject();
sort.put("$sort", new BasicDBObject("insensitive", 1));
pipe.add(sort);
AggregationOutput agg = coll.aggregate(pipe);
for (DBObject result : agg.results()) {
System.out.println(result);
}
If you want to sort and return all data in a document, you can add document: "$$ROOT"
db.collection.aggregate([
{
$project: {
field: 1,
insensitive: { $toLower: "$field" },
document: "$$ROOT"
}
},
{ $sort: { insensitive: 1 } }
]).toArray()
Tried all the above and answers
Consolidating the result
Answer-1:
db.collection.aggregate([
{ "$project": {
"field": 1,
"insensitive": { "$toLower": "$field" }
}},
{ "$sort": { "insensitive": 1 } } ])
Aggregate query converts the field into lower, So performance is low for large data.
Answer-2:
db.collection.find({}).collation({locale: "en"}).sort({"name":1})
By default mongo follows uft-8 encoding(Z has high piriority then a) rules ,So overriding with language-specific rules.
Its fast compare to above query
Look into an official document to customize rules
https://docs.mongodb.com/manual/reference/collation/
We solve this problem with the help of .sort function in JavaScript array
Here is the code
function foo() {
let results = collections.find({
_id: _id
}, {
fields: {
'username': 1,
}
}).fetch();
results.sort((a, b)=>{
var nameA = a.username.toUpperCase();
var nameB = b.username.toUpperCase();
if (nameA nameB) {
return 1;
}
return 0;
});
return results;
}