The collectionNames method of the native driver’s Db object accepts an optional collection name filter as a first parameter to let you check the existence of a collection: db.collectionNames(collName, function(err, names) { console.log(‘Exists: ‘, names.length > 0); }); In the 2.x version of the MongoDB native driver, collectionNames has been replaced by listCollections which accepts …
MongoDB is fast because its web scale! Its a fun video and well worth everyone watching, but it does answer your question – that most of the noSQL engines like MongoDB are not robust and not resilient to crashes and other outages. This security is what they sacrifice to gain speed.
The error you are getting indicates that the NPM package for MongoDB is not correctly installed. The fix here depends on how you plan to leverage NPM. The NPM package manager operates has two different modes of operation: local and global. The first (and default) mode is “local”. If you go to the folder with …
I add the line (below) in application.properties and works fine: logging.level.org.springframework.data.mongodb.core.MongoTemplate=DEBUG for query: @Query(“{$and: [{‘$or’ : [{ ‘name’: {$regex : ?0, $options: ‘i’}}, {‘description’: {$regex : ?1, $options: ‘i’}}]}, { ‘deleted’ : ?2 }]}”) obtain this log: 2016-09-27 10:53:26.245 DEBUG 13604 — [nio-9090-exec-3] o.s.data.mongodb.core.MongoTemplate : find using query: { “$and” : [ { “$or” : …
If using mongoose, this issue can be solved by using .lean() to get a json object (instead of a mongoose one): dbName.find({}).lean() // execute query .exec(function(error, body) { //Some code });
Check Updated code below, in particular this part: {type: Schema.Types.ObjectId, ref: ‘Ingredient’} var mongoose = require(‘mongoose’); var Schema = mongoose.Schema; var IngredientSchema = new Schema({ name: String }); module.exports = mongoose.model(‘Ingredient’, IngredientSchema); var mongoose = require(‘mongoose’); var Schema = mongoose.Schema; var RecipeSchema = new Schema({ name: String, ingredients:[ {type: Schema.Types.ObjectId, ref: ‘Ingredient’} ] }); module.exports …
Use dot notation (e.g. advertisers.name) to query and retrieve fields from nested objects: db.agencies.find({ “advertisers.created_at”: { $gte: start, $lt: end } }, { _id: 1, program_ids: 1, “advertisers.name”: 1 } }).limit(1).toArray(); Reference: Retrieving a Subset of Fields and Dot Notation
Since pymongo version 3.7.0 and above count() is deprecated. Instead use Collection.count_documents. Running cursor.count or collection.count will result in following warning message: DeprecationWarning: count is deprecated. Use Collection.count_documents instead. To use count_documents the code can be adjusted as follows import pymongo db = pymongo.MongoClient() col = db[DATABASE][COLLECTION] find = {“test_set”:”abc”} sort = [(“abc”,pymongo.DESCENDING)] skip = …
Use sort and limit: db.col.find().sort({“datetime”: -1}).limit(1)
In MongoDB 2.6, the Aggregation Framework has a new array $size operator you can use: > db.mycollection.insert({‘foo’:[1,2,3,4]}) > db.mycollection.insert({‘foo’:[5,6,7]}) > db.mycollection.aggregate([{$project: { count: { $size:”$foo” }}}]) { “_id” : ObjectId(“5314b5c360477752b449eedf”), “count” : 4 } { “_id” : ObjectId(“5314b5c860477752b449eee0”), “count” : 3 }