mongodb-query

问题 I'm trying to get a list of documents that have the max value. I can specify it if I know the number of documents with max value (like in the solution in this another stackoverflow solution 'mongodb how to get max value from collections'), but I don't know how to do it if I don't know what the number of documents is. For example, using the following documents: {name:"a", age:10} {name:"b", age:11} {name:"d", age:12} {name:"c", age:12} So I know that there are 2 documents with max age of 12.

问题 I'm trying to get a list of documents that have the max value. I can specify it if I know the number of documents with max value (like in the solution in this another stackoverflow solution 'mongodb how to get max value from collections'), but I don't know how to do it if I don't know what the number of documents is. For example, using the following documents: {name:"a", age:10} {name:"b", age:11} {name:"d", age:12} {name:"c", age:12} So I know that there are 2 documents with max age of 12.

问题 I'm setting up my new RocketChat Server. The problem is that actually, Rocket Chat doesn't support CAS Account if they are not created by CAS. We have old accounts. I can add the CAS feature by doing this : Enter in the MongoDB Database with MongoDB Compass software on Windows, and add cas object in services object with my keyboard... https://i.imgur.com/AIMAlA6.png So as you can see I can add the CAS feature by doing this. I want to do that with code so I did this : 1 - Enter in rocketchat

问题 I am attempting to build a query for MongoDB in Java and I am running into this error, "Can't canonicalize query: BadValue Too many text expressions" whenever I run the query. The database is full of documents with a text property that is indexed for full text searching. I am trying to build a query to find any documents that match one or more of the queries in queryList and are within a certain time range. It works fine if there is only one query in the queryList, but fails otherwise. Any

问题 I'm using this for doing an upsert: Articles.update( { title: title }, { title: title, parent: type }, { upsert: true }, function(res) { return console.log(res); } ); console.log(needToGetID); Now I need to get the _id of the document which has been updated or inserted. I thought I can get that via callback, but res is undefined. I assume there is just one unique document which is defined by the query. Update Forgot to mention that I'm using meteor... 回答1: The intent of .update() is to

问题 I am using mongoose to perform CRUD operation on MongoDB. This is how my schema looks. var EmployeeSchema = new Schema({ name: String, description: { type: String, default: 'No description' }, departments: [] }); Each employee can belong to multiple department. Departments array will look like [1,2,3]. In this case departments.length = 3. If the employee does not belong to any department, the departments.length will be equal to 0. I need to find all employee where EmployeeSchema.departments

问题 I am using mongoose to perform CRUD operation on MongoDB. This is how my schema looks. var EmployeeSchema = new Schema({ name: String, description: { type: String, default: 'No description' }, departments: [] }); Each employee can belong to multiple department. Departments array will look like [1,2,3]. In this case departments.length = 3. If the employee does not belong to any department, the departments.length will be equal to 0. I need to find all employee where EmployeeSchema.departments

问题 I am using mongoose to perform CRUD operation on MongoDB. This is how my schema looks. var EmployeeSchema = new Schema({ name: String, description: { type: String, default: 'No description' }, departments: [] }); Each employee can belong to multiple department. Departments array will look like [1,2,3]. In this case departments.length = 3. If the employee does not belong to any department, the departments.length will be equal to 0. I need to find all employee where EmployeeSchema.departments

问题 I'm storing time series data in a mongoDB collection with one data point every 15min. But sometimes, due to bad conditions, some data points get lost. I have a dataset as follows: {"device_id": "ABC","temp": 12,"timestamp": 2020-01-04T17:48:09.000+00:00} {"device_id": "ABC","temp": 10,"timestamp": 2020-01-04T18:03:09.000+00:00} {"device_id": "ABC","temp": 14,"timestamp": 2020-01-04T18:18:09.000+00:00} missing frame missing frame {"device_id": "ABC","temp": 13,"timestamp": 2020-01-04T19:03:09

问题 I have next 3 documents in mongodb: document 1: { "name": "device1", "camera": { "number": 3 } } document 2: { "name": "device2", "camera": { "number": 1 } } document 3: { "name": "device3", "wifi": { "number": 2 } } My aim is to find all devices which modules' number > 1, the module maybe camera , wifi or others. I know I can use next to get the device: > db.devices.find({"camera.number":{$gt:1}}) { "_id" : ObjectId("5f436a3df716cb47d319245e"), "name" : "device1", "camera" : { "number" : 3 }