mongodb-query

问题 How do I turn this query in a valid mongodb Query in mongodb shell. { 'cars.owner.$ref' : 'users' } cars.owner is a DBRef here, but $ref is invalid I get this error: "$err" : "Positional operator does not match the query specifier." My objective here is to figure out if there are any cars "owned" by different collections then users. 回答1: MongoDB documentation (database-reference) says following: MongoDB applications use one of two methods for relating documents: Manual references where you

问题 I use phalcon with mongo db. Model is Collection . I want use find to get SELECT * FROM Users WHERE Username LIKE '%TienNguyen%' I see in mongo db have query b.users.find( { Username: /TienNguyen/ } ) But in collection of Phalcon. How do I code it. I tried Users::find([['Username' => "/TienNguyen/"]]); It is not working. Please help me 回答1: As was mentioned above, regex searches that are not anchored at the beginning of the string can be very expensive because they require a full table scan.

问题 I use phalcon with mongo db. Model is Collection . I want use find to get SELECT * FROM Users WHERE Username LIKE '%TienNguyen%' I see in mongo db have query b.users.find( { Username: /TienNguyen/ } ) But in collection of Phalcon. How do I code it. I tried Users::find([['Username' => "/TienNguyen/"]]); It is not working. Please help me 回答1: As was mentioned above, regex searches that are not anchored at the beginning of the string can be very expensive because they require a full table scan.

问题 I have a mongo/mongoose schema which when queried retruns documents such as { "_id" : ObjectId("5907a5850b459d4fdcdf49ac"), "amount" : -33.3, "name" : "RINGGO", "method" : "VIS", "date" : ISODate("2017-04-26T23:00:00Z"), "importDate" : ISODate("2017-05-01T21:15:49.581Z"), "category" : "Not Set", "__v" : 0 } { "_id" : ObjectId("5907a5850b459d4fdcdf49ba"), "amount" : -61.3, "name" : "Amazon", "method" : "VIS", "date" : ISODate("2017-03-23T00:00:00Z"), "importDate" : ISODate("2017-05-01T21:15:49

问题 I am calling the MongoDB aggregate function in my code as : AggregationOutput output = collection.aggregate( matchUserID, unwindF, matchFUsers,projection); I have tested my code in my localhost, and it works perfect. When I am using the same in another DB (version 2.2.1), it gives this error : com.mongodb.CommandResult$CommandFailure: command failed [aggregate]: { "serverUsed" : "<server address>" , "errmsg" : "no such cmd: aggregate" , "bad cmd" : { "aggregate" : .... } Any clue why ? 回答1:

问题 Given collection foo with the following index: db.foo.createIndex( { a : 1, b : 1, c : 1 } ) We need to select which of the following queries will use the index? db.foo.find( { c : 1 } ).sort( { a : -1, b : 1 } ) db.foo.find( { b : 3, c : 4 } ) db.foo.find( { a : 3 } ) db.foo.find( { c : 1 } ).sort( { a : 1, b : 1 } ) I'm surprised that 3 , 4 are correct options and 1 , 2 are not. Why is the following queries will use the index? db.foo.find( { a : 3 } ) This seems to be able to use the index

问题 I have a question that is similar to this other question but not exactly the same because my data structure is more deeply nested, and the accepted answer did not resolve the issue. Technologies: MongoDB 3.6, Mongoose 5.5, NodeJS 12 I am trying to query a deeply nested array of objects. The query will accept a "Start Date" and an "End Date" from the user. Item Report is an array of subdocuments that contains another array of subdocuments "Work Done By". All WorkDoneBy objects that have a

问题 I have a item collection with the following format: { "_id": 123, "items": [{ "name": "item1", "status" : "inactive", "created" : ISODate("2018-02-14T10:39:28.321Z") }, { "name": "item2", "status" : "active", "created" : ISODate("2018-02-14T10:39:28.321Z") }, { "name": "item3", "status" : "active", "created" : ISODate("2018-02-14T10:39:28.321Z") }, { "name": "item4", "status" : "inactive", "created" : ISODate("2018-02-14T10:39:28.321Z") }, { "name": "item5", "status" : "active", "created" :

问题 { _id:'1', name:'apple', option:[{ weight:'10', size:'40' price:'40', }, {weight:'40', size:'40' price:'200'}] } If weight or the size is different I want to upsert new object in the array, if both the size and the weight matched I want to update it. How can I do it? 回答1: Similar to your previous question, you use .bulkWrite() but since the array element selection has "multiple conditions" this is where you use $elemMatch: db.collection.bulkWrite([ { "updateOne": { "filter": { "_id": "1",

问题 I have the following document in the entities collection at Mongo (a 2dsphere index for location.coords is in place): > db.entities.find({},{location: 1}).pretty() { "_id" : { "id" : "en3", "type" : "t", "servicePath" : "/" }, "location" : { "attrName" : "position", "coords" : { "type" : "MultiPoint", "coordinates" : [ [ -3.691944, 40.418889 ], [ 4.691944, 45.418889 ] ] } } } As far as I have checked, $geoWithin only matches when the geometry includes all the points of the MultiPoint, e.g: >