MongoDB by Example

Collection of MongoDB tips and tricks, want to add your tips? Checkout contributing.md

P.S: All these commands are tested on MongoDB shell version v3.4.2.

MongoDB Package Component

• Import data into the collection using JSON generated By Mongoexport
• Import data into the collection using regular JSON
• Restore data into Atlas using dump
• Import data into Atlas using mongoimport

Mongo Shell

• Show list of Databases
• Copy Database
• Copy Database Using Host and user credential

MongoDB CRUD Operations

each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the MongoDB driver automatically generates an ObjectId for the _id field.

• Insert a single document
• Insert multiple documents
• Inserts a document or documents into a collection
• Update a field to an empty array in all documents
• Insert a new field into a collection
• Find value inside array
• Find documents where field value is empty
• Find documents where field value is non empty

Import data into the collection using JSON generated By Mongoexport

mongoimport --db <databaseName> --collection <collectionName> --drop --file <jsonFile>.json

Import data into the collection using regular JSON

mongoimport --db <databaseName> --collection <collectionName> --drop --file <jsonFile>.json --jsonArray

Restore data into Atlas using dump

mongorestore --ssl --host atlas-host1:27017,atlas-host2:27017,atlas-host3:27017 -u usename -p mypassword dump

Import data into Atlas using mongoimport

mongoimport --host atlas-host1:27017,atlas-host2:27017,atlas-host3:27017 --ssl -u username -p 'password' --authenticationDatabase admin --db <database> --collection <collection> --file <file.json>

Show list of Databases

show dbs

Copy Database

db.copyDatabase(fromdb, todb)

Copy Database Using Host and user credential

db.copyDatabase(fromdb, todb, fromhost, username, password, mechanism)

Insert a single document

db.mycollection.insertOne(
   { bookName: "Indian History", price: 100, tags: ["History"], size: { h: 28, w: 35.5, uom: "cm" } }
  )

Insert multiple documents

db.mycollection.insertMany([
   { bookName: "Modern science", price: 500.34, tags: ["science"], size: { h: 28, w: 35.5, uom: "cm" } },
   { bookName: "Computer Design", price: 300, tags: ["computer"], size: { h: 28, w: 35.5, uom: "cm" } },
  )]

Inserts a document or documents into a collection

db.mycollection.insert([
   { bookName: "Modern science", price: 500.34, tags: ["science"], size: { h: 28, w: 35.5, uom: "cm" } },
   { bookName: "Computer Design", price: 300, tags: ["computer"], size: { h: 28, w: 35.5, uom: "cm" } },
  ])
    
    
  
db.mycollection.insert(
   { bookName: "Indian History", price: 100, tags: ["History"], size: { h: 28, w: 35.5, uom: "cm" } }
   )

Update a field to an empty array in all documents

db.mycollection.update(
{}, 
{$set : {fieldName:[]} }, {multi:true}
)

Insert a new field into a collection

db.mycollection.updateMany(
{}, 
{$set :{"newFieldName":""}}
)

Find value inside array

field : studentMarks[{rollNo:1,marks:10},{rollNo:2,marks:5},{rollNo:3,marks:10}]

//query to get documents where students got 10 marks

db.mycollection.find( 
{ "studentMarks": { $elemMatch: { "marks": 10 } } } 
)

Find documents where field value is empty

//query to get documents where name is empty

db.mycollection.find( 
{ "name": ""} 
)

Find documents where field value is non empty

//query to get documents where name is non empty

db.mycollection.find( 
{ "name": {$ne : ""}} 
)