mongodb-query

问题 How can I use indexes in aggregate? I saw the document https://docs.mongodb.com/manual/core/aggregation-pipeline/#pipeline-operators-and-indexes The $match and $sort pipeline operators can take advantage of an index when they occur at the beginning of the pipeline. Is there any way of using index not the beginning situation? like $sort , $match or $group Please help me 回答1: An index works by keeping a record of certain pieces of data that point to a given record in your collection. Think of

问题 I have two models in user.js and userProfile.js of mongoose, where I want to get documents using a join query but I have not take ref in user schema so I have code as below: user.js var userSchema = new Schema({ nick_name:{type:String}, email: {type: String}, password: {type: String}, is_active:{type:String,enum:['1','0'],default:"1"}, },{ collection: 'user'}); userProfile.js var userProfileSchema = new Schema({ user_id:{type:Schema.Types.ObjectId, ref:'User'}, first_name:{type:String}, last

问题 I have two models in user.js and userProfile.js of mongoose, where I want to get documents using a join query but I have not take ref in user schema so I have code as below: user.js var userSchema = new Schema({ nick_name:{type:String}, email: {type: String}, password: {type: String}, is_active:{type:String,enum:['1','0'],default:"1"}, },{ collection: 'user'}); userProfile.js var userProfileSchema = new Schema({ user_id:{type:Schema.Types.ObjectId, ref:'User'}, first_name:{type:String}, last

问题 I'm looking for an advice about which indexing strategy to use in MongoDb 3.4. Let's suppose we have a people collection of documents with the following shape: { _id: 10, name: "Bob", age: 32, profession: "Hacker" } Let's imagine that a web api to query the collection is exposed and that the only possibile filters are by name or by age . A sample call to the api will be something like: http://myAwesomeWebSite/people?name="Bob"&age=25 Such a call will be translated in the following query: db

问题 I'm looking for an advice about which indexing strategy to use in MongoDb 3.4. Let's suppose we have a people collection of documents with the following shape: { _id: 10, name: "Bob", age: 32, profession: "Hacker" } Let's imagine that a web api to query the collection is exposed and that the only possibile filters are by name or by age . A sample call to the api will be something like: http://myAwesomeWebSite/people?name="Bob"&age=25 Such a call will be translated in the following query: db

问题 { _id:xxxxstoreid store:{ products:[ { _id:xxxproductid, name:xxx, img:url, } ] } } since i cannot predict the request for update, params may have just name or it may have both. here is my query,it updates successfully but it removes other fields if they are not present in the params. eg: var params={_id:xxid,name:'xxx',img:'xxx'} or var params={_id:xxid,name:'xxx'} in this case if params have just name it removes img field and updates. User.update({'store.products._id':params._id},{$set:{

问题 { _id:xxxxstoreid store:{ products:[ { _id:xxxproductid, name:xxx, img:url, } ] } } since i cannot predict the request for update, params may have just name or it may have both. here is my query,it updates successfully but it removes other fields if they are not present in the params. eg: var params={_id:xxid,name:'xxx',img:'xxx'} or var params={_id:xxid,name:'xxx'} in this case if params have just name it removes img field and updates. User.update({'store.products._id':params._id},{$set:{

问题 { _id:xxxxstoreid store:{ products:[ { _id:xxxproductid, name:xxx, img:url, } ] } } since i cannot predict the request for update, params may have just name or it may have both. here is my query,it updates successfully but it removes other fields if they are not present in the params. eg: var params={_id:xxid,name:'xxx',img:'xxx'} or var params={_id:xxid,name:'xxx'} in this case if params have just name it removes img field and updates. User.update({'store.products._id':params._id},{$set:{

问题 I have a collection like this: { "_id" : ObjectId("5bd1686ba64b9206349284db"), "type" : "Package", "codeInstances" : [ { "name" : "a", "description" : "a" }, { "name" : "b", "description" : "b1" }, { "name" : "b", "description" : "b2" } ] } { "_id" : ObjectId("5bd16ab8a64b92068d485054"), "type" : "Package", "codeInstances" : [ { "name" : "a", "description" : "a" }, { "name" : "b", "description" : "b3" } ] } The following structure is what I want: { "name" : "b", "description" : "b1" }, {

问题 I have a query to find if a user CreatedBy is in a SharedWith . I want to inverse the query to check if the CreatedBy is not in SharedWith . [ { "$match": { "$and": [ { "$and": [ { "SharedWith": { "$exists": true } }, { "$expr": { "$in": [ "$CreatedBy", "$Multi_User" ] } } ] } ] } } ] MongoDB does not support a direct $nin or $not for $and query. Any idea how to achieve this. The user document looks like this, Collection = [ {"CreatedBy": {"_id": "User001", "Email": "user@eg.com", "Name":