mongodb-query

Since v3.4 collations are available for find operations, especially as matches for diacritic characters are concerned. While a find query with a definite value ($eq opeartor or corresponding construct) will match letters and correspondent diacritics, the same is not true if a $regex is used in order to achieve a match on a partial search string (a 'LIKE'). Is there a to make the $regex query use the collation the same way than the $eq query? consider example collection testcoll: { "_id" : ObjectId("586b7a0163aff45945462bea"), "city" : "Antwerpen" }, { "_id" : ObjectId("586b7a0663aff45945462beb

I am struggling with the newish (lovely) lookup operator in MongoDB. I have 3 collections: artists { "_id" : ObjectId("5b0d2b2c7ac4792df69a9942"), "name" : "Dream Theater", "started_in" : NumberInt(1985), "active" : true, "country" : "US", "current_members" : [ ObjectId("5b0d2a7c7ac4792df69a9941") ], "previous_members" : [ ObjectId("5b0d2bf57ac4792df69a9954") ], "albums" : [ ObjectId("5b0d16ee7ac4792df69a9924"), ObjectId("5b0d47667ac4792df69a9994") ], "genres" : [ "prog metal", "prog rock" ] } Albums { "_id" : ObjectId("5b0d16ee7ac4792df69a9924"), "title" : "Images and words", "released" :

How to get the most common distinct values of a key in query results. Consider a collection 'collectionSample' { name : 'a', value: 10, word : 'baz' }, { name : 'a', value: 65, word : 'bar' }, { name : 'a', value: 3, word : 'foo' }, { name : 'b', value: 110, word : 'bar' }, { name : 'b', value: 256, word : 'baz' } Here I want to find the mode of key 'name', that is the most repeated distinct 'name'. The result I'm hoping to get is like {'most_common_distinct_val':a} //since a is count 3 and b is count 2 How to query it in NodeJs mongo client? 2017-08-01 Update As release of MongoDB 3.4, the

i am working on aggregation of mongodb collection.my mongodb collection has creation_time in timestamp.How will i can collect same day result and aggregate with next day result.Suppose i have to collect data for 5 days.My mongodb collection is: { "_id" : "1522845653126" }, { "_id" : "1522838153324" }, { "_id" : "1513421466415" }, { "_id" : "1515488183153" }, { "_id" : "1521571234500" } How can i calculate.How many entry are save on specific date?? nd suppose I want is to query results that returns a running total of the aggregation, like: { time: "2013-10-10" count: 3, }, { time: "2013-10-11"

I am trying to design a Mongo Db connection class where I am maintaning MongoClient as static. private static MongoClient client = null; public static DB connectToMongo() throws Exception { if (null != client) { return client.getDB(DBNAME); } client = new MongoClient(HOST,PORT); return client.getDB(DBNAME); } My whole web application uses the above method to connect to Mongo as follows: db = MongoDBConnection.connectToMongo(); collection = db.getCollection("collectionName"); After performing DB operations I never call the close connection for MongoClient. The connection class would always

I am finding the mongodb aggregation framework to be extremely powerful - it seems like a good option to flatten out an object. My schema uses a an array of sub objects in an array called materials. The number of materials is variable, but a specific field (category) will be unique across objects in the array. I would like to use the aggregation framework to flatten the structure and dynamically rename the fields based on the value of the category field. I could not find an easy way to accomplish this using a $project along with $cond. Is there a way? The reason for the array of material