mongodb-query

问题 Our code with mongo-java-driver 3.0.4 used to be like - DBCollection dbCollection = mongoClient.getDB(databaseName).getCollection(collectionName); QueryBuilder queryBuilder = new QueryBuilder(); /** queryBuilder.put() for building the query */ DBCursor dbCursor = dbCollection.find(queryBuilder.get()); while(dbCursor.hasNext()) { DBObject dbObject = dbCursor.next(); // add entries to a list of TDocument type } Converting this to the mongo-java-driver 3.3.0, I ended up with this -

问题 Our code with mongo-java-driver 3.0.4 used to be like - DBCollection dbCollection = mongoClient.getDB(databaseName).getCollection(collectionName); QueryBuilder queryBuilder = new QueryBuilder(); /** queryBuilder.put() for building the query */ DBCursor dbCursor = dbCollection.find(queryBuilder.get()); while(dbCursor.hasNext()) { DBObject dbObject = dbCursor.next(); // add entries to a list of TDocument type } Converting this to the mongo-java-driver 3.3.0, I ended up with this -

问题 I'm still a beginner with MongoDB and I'm getting crazy to create a complex (for me) query with it. So, my model is: { email: String, name: String, orientation: String, location: { country: String, city: String }, contacts: { phone: String, email: String, website: String } } Now I created a query like this: User.aggregate([ { $group: { _id: { city: '$location.city', country: '$location.country', orientation: '$orientation' }, count: { $sum: 1 } } }, { $group: { _id: '$_id.country', count: {

问题 I was thinking of setting up an like the following. There will be a login page that an admin can access and a worker can access. the admin can make it so that the workers could see certain data(the admin can create workers). The main problem right now is hooking this up with passport. I think the user document look something like this {username: "user1", password : "pass1", role : "admin", workers :[ {username : "worker1", password : "workerpass1"}, {username : "worker2", password :

问题 Objective Fix my make_pipeline() function to, using an aggregation query, count the number of tweets for each user, add them to an array and return the 5 users with the most tweets. Exercise Using an aggregation query, count the number of tweets for each user. In the same $group stage, use $push to accumulate all the tweet texts for each user. Limit your output to the 5 users with the most tweets. Your result documents should include only the fields: "_id" (screen name of user), "count"

问题 I have a schema like this: { tags:[ { id:"t1", score:70 }, { id:"t1", score:60 } ] } I want to sort the query on tag.id search to get sorted by the corresponding score. So if I search db.collection.find({tags.id:"t1"}).sort({tags.score:-1}) , it sorted by score of the "t1" object not other tags. Any suggestion? 回答1: If you need to calculate out something like this at runtime, with "filtered" content from the array determining the sort order, then you best do something with .aggregate() to

问题 How to get all the document under array in mongodb java. My Database is as below. Want to retrieve all the data under array 198_168_1_134 . below is some of What i tried, eventlist.find(new BasicDBObject("$match","192_168_10_17")) eventlist.find(new BasicDBObject("$elemMatch","192_168_10_17")) eventlist.find(null, new BasicDBObject("$192_168_10_17", 1)) 回答1: You have two options: using .find() with cherry-picking which document you have to have fetched. using the aggregation framework by

问题 I am working on an app that contain details of an academic year in Multilevel structure of mongoDB database. For this I've created structure like this: [ { "_id" : ObjectId("5a1519a71fe8cc4df5888ff5"), "academicyear" : "2016-2017", "departments" : [ { "deptname" : "computer", "semesters" : [ { "sem" : "2", "classes" : [ { "class" : "1", "theory" : [ { "subname" : "DS", "faculty" : [ { "facultyname" : "KSS", "facultydept" : "COMP" } ] } ], "practical" : [ { "subname" : "DS", "batch" : [ {

问题 I am 1 day old to MongoDB so bear with me. I am simply trying to output a simple query to a *.json file. The query is: db.collection.findOne() // collection is substituted with the correct collection name, the query preludes 'use db' command where db is substituted with correct db name Then, in reference to this article and a bunch of other SO answers, I perform the following query: --eval "printjson(db.results.findOne())" >> sample.json I even created a blank sample.json file, and I

问题 I am doing a comparison of mongodb with respect to mysql and imported the mysql data into the mongodb collection (>500000 records). the collection looks like this: { "_id" : ObjectId(""), "idSequence" : , "TestNumber" : , "TestName" : "", "S1" : , "S2" : , "Slottxt" : "", "DUT" : , "DUTtxt" : "", "DUTver" : "", "Voltage" : , "Temperature" : , "Rate" : , "ParamX" : "", "ParamY" : "", "Result" : , "TimeStart" : new Date(""), "TimeStop" : new Date(""), "Operator" : "", "ErrorNumber" : ,