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How to Install Node.js and NPM Windows 10

Node.js is a cross-platform environment that runs and executes JavaScript codes outside the browser. Since its first release, Node.js has gained massive popularity among developers. As it uses JavaScript, it is fast and easy to pick up and avails excellent scalability, making it a favourite among web developers. The Node.js framework is available for all the major operating systems like Windows, Ubuntu, and Mac.   s-logo.jpg Are you ready to start working with node.js? Before anything else, let us understand how to install node.js on windows 10. In this tutorial, you will learn- How to Download & Install Node.js on Windows 10 How to uninstall Node.js on windows How to Install NPM on Windows 10 Running your first "Hello World" application in Node.js PrerequisitesBelow we get started, here are a few system requirements to download, install, and set up React-Native on Windows 10. Hardware requirementsRAM 4GB CPU Intel Core i3TM i3 HQ CPU @2.50 GHz ROM 256 GB Software requirementChocolatey Attention: You will also need a stable internet connection because we will be downloading most of this software. Installation procedureStep-by-step procedure to Install node.js on Windows 10Undoubtedly, the first step to getting started on working with node.js is installing the software package in your system. Once done, follow the step-by-step tutorial on how to proceed to get the node.js framework successfully installed in your system. We will also look at how you can uninstall the program from your computer completely.Step-1: Download node.js installer into your systemVisit the official node.js site https://nodejs.org/en/download/ and click on Windows installer to download the necessary software in your system. The installer contains the NPM package. Based on the system you want to install, choose 32-bit installer or 64-installer and proceed.Note: When you click on download, you will be asked to choose the file location you want to store the instal.msi binary files. Choose a secure file location of your choice.   Step-2: Run the installationOnce you choose the path, the next step is to double-click the instal.msi binary files to initiate the installation process. Furthermore, you will be asked for permission to run the application.   Warning: On the open file security warning, there is a cancel option as well. Don't click on the cancel option, or else you may perhaps need to restart the installation. You can use the back button to check your previous installation step. On running the application, you will proceed to an interface with a welcome message. Click the "Next" button and proceed with the installation as shown in the image. Step-3: Accept the terms of usageAfter clicking the next option, you will get an end-user license agreement. Read the terms of using the software, and then click on next.  N.B. You will find a square box asking you to agree with the terms, and only when you have read the terms, you will be allowed to proceed further.  Step-4: Specify the path Once you have accepted the terms and conditions, the next step is to specify the path where you want to install node.js. Your file location is the path where you must install the node.js in your system.Once you have specified the path, click on the Next button to proceed with the installation. Step-5: Select the default optionsOn proceeding with the Next option, the custom page setup will open up on the screen. Here you will get four icons as stated below: node.js runtime NPM package manager Online documentation shortcuts Add to PATHSelect all the options as default and then proceed with the Next option. Step-6 Initiate the installationAfter all these steps, you will see an install button to process the installation of node.js on Windows. Click on the install button to initiate the installation of node.js on your Windows. Based on your system performance it may take a couple of minutes to install node.js on your system. Once the installation is complete, you will get a message on your screen as — Node.js has been successfully installed.Step-7: Complete the installationOn clicking the Finish button, the process of installation of node.js is successfully completed. Congratulations! You have successfully installed node.js on your Windows 10. Verifying the install To verify that the node.js has been successfully installed in your system, go to the command prompt and run it as administrator. Now use the following command to check the node.js version installed in your system. node -v The message v14.16.1 verifies that node.js has been successfully installed on your windows, and you are ready to use it. Alternative MethodDo you know there is also an alternative way to download & install Node.js and NPM on Windows 10? Using a software package manager called Chocolatey, you can install node.js and NPM on your machine. Let us understand how to install node.js and NPM on windows using Chocolatey step by step. We will also look at how to uninstall the same with Chocolatey. Installing Chocolatey.The first process that you need to do is to install Chocolatey in your system. Take a note that the installation of Chocolatey requires administrator access to the computer’s command prompt to run.  Choose the option – get started as shown below:Once you go to the official Chocolatey website, select the individual as shown in the picture.  Open Windows PowerShell and run as administrator. Now run the command and then press enter. Get-ExecutionPolicy On running this command, you will get a message as Restricted. Once you get the message as Restricted, continue and then run another command and press enter. Set-Execution Policy All Signed You will get a screen with execution policy changes. Select the A (Yes to all) option and then press Enter.Copy and paste the command mentioned below: Set-ExecutionPolicy Bypass -Scope Process -Force; [System.Net.ServicePointManager]::SecurityProtocol =[System.Net.ServicePointManager]::SecurityProtocol -bor 3072; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))To check whether you have installed it well, open the command prompt below: choco -version If you have installed it well, you will see the display of the Chocolatey version you have installed on the screen as below: Boom! Chocolatey is now successfully installed in your system. Install Node.js Using Chocolatey that you have just installed, now we can install Node.js in the system. Open the command prompt as the administrator and put in the Chocolatey command prompt as mentioned below:  Choco install -y nodejs.install To confirm if it has installed correctly on the computer, you need to execute the command below on the computer command prompt, as an administrator: node --version If you have followed the steps correctly, the installation would have been successful and the message below will display on your screen after the installation has been completed. After installing the Node.js, the Node Package Manager NPM automatically gets installed in the system. Run the command below to check the installation of NPM. The displayed message below verifies that the installation of NPM is successful.Writing your first program on node.js Now that you have successfully downloaded and installed node.js in your system, let’s learn how to write a program using node.js  Follow the steps to write your first program. Step-1: Create a folder and name it. (Here we have created a folder named Node Programs. Step-2: Open any code editor of your choice (here we are using Visual Studio Code). Step-3: Click on the file menu and open the folder you just created.  Step-4: Once you open the folder, create a file and name it. (Here we have created a file named as welcome.js)  Step-5: Write your program and save it using (Ctrl + S). Step-6: Start debugging using the shortcut f5. And that’s it! You have successfully created your first project using node.js. (Goodbye-COVID-19 was the message we wanted to print and it is running successfully). Uninstalling Node.jsUninstalling node.js needs a manual process. Here is a step-by-step guide on how to uninstall node.js from your system.  Step-1: Go to the file location where you have stored node.jsStep-2: Select the node.js row and right-click on it. Out of the three options available, click on uninstall.   Step-3: After clicking on the uninstall option, the uninstalling starts. Once done, you will successfully uninstall node.js from your system. Summary In this article we have covered how to install Node.js with the help of the MSI installation module from the Node.js website. Besides, we have also learned to install the necessary modules needed to run a Node.js application. Node.js can also be installed with the help of a package manager Chocolatey. With the use of simple commands in the command prompt or in the Windows PowerShell as mentioned above, we have seen how to download node.js using the Chocolatey package manager that automatically downloads the necessary files and then installs them on the client machine. Lastly, we have learned about the uninstallation of node.js completely from your system. In a nutshell, we have seen how to install node.js using different methods. That’s all you need to get started with node.js. You are free to choose any terminal of your preference. Keep in mind: Node.js was never made to tackle the process scaling issue but made to address the I/O scaling issue.  Red Flags: While installing node.js, make the right choice between a 32-bit installer and a 64-bit installer matching your system. For instance, if you have a 64-bit operating system  you will be unable to install the 32-version of node.js. Likewise, if you have a 32-bit operating system, you will be unable to install the 62-version of node.js. Therefore, the key here is to know your system and proceed with the next steps.  

How to Install Node.js and NPM Windows 10

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How to Install Node.js and NPM Windows 10

Node.js is a cross-platform environment that runs and executes JavaScript codes outside the browser. Since its first release, Node.js has gained massive popularity among developers. As it uses JavaScript, it is fast and easy to pick up and avails excellent scalability, making it a favourite among web developers. The Node.js framework is available for all the major operating systems like Windows, Ubuntu, and Mac.   

s-logo.jpg 

Are you ready to start working with node.js? Before anything else, let us understand how to install node.js on windows 10. 

In this tutorial, you will learn- 

  • How to Download & Install Node.js on Windows 10 
  • How to uninstall Node.js on windows 
  • How to Install NPM on Windows 10 
  • Running your first "Hello World" application in Node.js 

Prerequisites

Below we get started, here are a few system requirements to download, install, and set up React-Native on Windows 10. 

Hardware requirements

  • RAM 4GB 
  • CPU Intel Core i3TM i3 HQ CPU @2.50 GHz 
  • ROM 256 GB 

Software requirement

  • Chocolatey 

Attention: You will also need a stable internet connection because we will be downloading most of this software. 

Installation procedure

  • Step-by-step procedure to Install node.js on Windows 10

Undoubtedly, the first step to getting started on working with node.js is installing the software package in your system. Once done, follow the step-by-step tutorial on how to proceed to get the node.js framework successfully installed in your system. We will also look at how you can uninstall the program from your computer completely.

Step-1: Download node.js installer into your system

Visit the official node.js site https://nodejs.org/en/download/and click on Windows installer to download the necessary software in your system. The installer contains the NPM package. Based on the system you want to install, choose 32-bit installer or 64-installer and proceed.Download node.js installer into your system

Note: When you click on download, you will be asked to choose the file location you want to store the instal.msi binary files. Choose a secure file location of your choice.   Download node.js installer into your system

Step-2: Run the installation

Once you choose the path, the next step is to double-click the instal.msi binary files to initiate the installation process. Furthermore, you will be asked for permission to run the application.   

Warning: On the open file security warning, there is a cancel option as well. Don't click on the cancel option, or else you may perhaps need to restart the installation. You can use the back button to check your previous installation step. 

On running the application, you will proceed to an interface with a welcome message. Click the "Next" button and proceed with the installation as shown in the image. 

Run the installation

Step-3: Accept the terms of usageAccept the terms of usage

After clicking the next option, you will get an end-user license agreement. Read the terms of using the software, and then click on next.  

N.B. You will find a square box asking you to agree with the terms, and only when you have read the terms, you will be allowed to proceed further.  

Step-4: Specify the path 

Once you have accepted the terms and conditions, the next step is to specify the path where you want to install node.js. Your file location is the path where you must install the node.js in your system.Specify the path

Once you have specified the path, click on the Next button to proceed with the installation. 

Step-5: Select the default options

On proceeding with the Next option, the custom page setup will open up on the screen. Here you will get four icons as stated below: 

  • node.js runtime 
  • NPM package manager 
  • Online documentation shortcuts 
  • Add to PATH

Select the default options

Select all the options as default and then proceed with the Next option. 

Step-6 Initiate the installation

After all these steps, you will see an install button to process the installation of node.js on Windows. Click on the install button to initiate the installation of node.js on your Windows. Based on your system performance it may take a couple of minutes to install node.js on your system. Once the installation is complete, you will get a message on your screen as — Node.js has been successfully installed.Initiate the installation

Step-7: Complete the installation

On clicking the Finish button, the process of installation of node.js is successfully completed. Congratulations! You have successfully installed node.js on your Windows 10. Complete the installationVerifying the install 

To verify that the node.js has been successfully installed in your system, go to the command prompt and run it as administrator. Now use the following command to check the node.js version installed in your system. 

node -v 

The message v14.16.1 verifies that node.js has been successfully installed on your windows, and you are ready to use it. Installation of Node.js and NPM on Windows 10

Alternative Method

Do you know there is also an alternative way to download & install Node.js and NPM on Windows 10? Using a software package manager called Chocolatey, you can install node.js and NPM on your machine. Let us understand how to install node.js and NPM on windows using Chocolatey step by step. We will also look at how to uninstall the same with Chocolatey. 

Installing Chocolatey.

The first process that you need to do is to install Chocolatey in your system. Take a note that the installation of Chocolatey requires administrator access to the computer’s command prompt to run.  

  • Choose the option – get started as shown below:

Installing Chocolatey.

  • Once you go to the official Chocolatey website, select the individual as shown in the picture.  

Installing Chocolatey.

  • Open Windows PowerShell and run as administrator. Now run the command and then press enter. 

Get-ExecutionPolicy 

  • On running this command, you will get a message as Restricted. Once you get the message as Restricted, continue and then run another command and press enter. 

Set-Execution Policy All Signed

Installation of Node.js and NPM on Windows 10

  • You will get a screen with execution policy changes. Select the A (Yes to all) option and then press Enter.

Installation of Node.js and NPM on Windows 10

  • Copy and paste the command mentioned below: 
Set-ExecutionPolicy Bypass -Scope Process -Force; [System.Net.ServicePointManager]::SecurityProtocol =[System.Net.ServicePointManager]::SecurityProtocol -bor 3072; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))

Installation of Node.js and NPM on Windows 10 To check whether you have installed it well, open the command prompt below: 

choco -version 

If you have installed it well, you will see the display of the Chocolatey version you have installed on the screen as below: Installation of Node.js and NPM on Windows 10 Boom! Chocolatey is now successfully installed in your system. 

Install Node.js 

Using Chocolatey that you have just installed, now we can install Node.js in the system. Open the command prompt as the administrator and put in the Chocolatey command prompt as mentioned below:  

Choco install -y nodejs.install 

To confirm if it has installed correctly on the computer, you need to execute the command below on the computer command prompt, as an administrator: 

node --version 

Installation of Node.js and NPM on Windows 10 If you have followed the steps correctly, the installation would have been successful and the message below will display on your screen after the installation has been completed. 

After installing the Node.js, the Node Package Manager NPM automatically gets installed in the system. Run the command below to check the installation of NPM. The displayed message below verifies that the installation of NPM is successful.Installation of Node.js and NPM on Windows 10

Writing your first program on node.js 

Now that you have successfully downloaded and installed node.js in your system, let’s learn how to write a program using node.js  

Follow the steps to write your first program. 

  • Step-1: Create a folder and name it. (Here we have created a folder named Node Programs. 
  • Step-2: Open any code editor of your choice (here we are using Visual Studio Code). 

Installation of Node.js and NPM on Windows 10

  • Step-3: Click on the file menu and open the folder you just created.  

Installation of Node.js and NPM on Windows 10

  • Step-4: Once you open the folder, create a file and name it. (Here we have created a file named as welcome.js)  

Installation of Node.js and NPM on Windows 10

  • Step-5: Write your program and save it using (Ctrl + S). 
  • Step-6: Start debugging using the shortcut f5. 

Installation of Node.js and NPM on Windows 10

And that’s it! You have successfully created your first project using node.js. 

(Goodbye-COVID-19 was the message we wanted to print and it is running successfully). 

Uninstalling Node.js

Uninstalling node.js needs a manual process. Here is a step-by-step guide on how to uninstall node.js from your system.  

  • Step-1: Go to the file location where you have stored node.js

Installation of Node.js and NPM on Windows 10

  • Step-2: Select the node.js row and right-click on it. Out of the three options available, click on uninstall.  

Installation of Node.js and NPM on Windows 10

  •  Step-3: After clicking on the uninstall option, the uninstalling starts. 

Installation of Node.js and NPM on Windows 10

Once done, you will successfully uninstall node.js from your system. 

Summary 

  • In this article we have covered how to install Node.js with the help of the MSI installation module from the Node.js website. Besides, we have also learned to install the necessary modules needed to run a Node.js application. 
  • Node.js can also be installed with the help of a package manager Chocolatey. With the use of simple commands in the command prompt or in the Windows PowerShell as mentioned above, we have seen how to download node.js using the Chocolatey package manager that automatically downloads the necessary files and then installs them on the client machine. 
  • Lastly, we have learned about the uninstallation of node.js completely from your system. 

In a nutshell, we have seen how to install node.js using different methodsThat’s all you need to get started with node.js. You are free to choose any terminal of your preference. 

Keep in mind: Node.js was never made to tackle the process scaling issue but made to address the I/O scaling issue 

Red Flags: While installing node.js, make the right choice between a 32-bit installer and a 64-bit installer matching your system. For instance, if you have a 64-bit operating system  you will be unable to install the 32-version of node.js. Likewise, if you have a 32-bit operating system, you will be unable to install the 62-version of node.js. Therefore, the key here is to know your system and proceed with the next steps.  

Abhresh

Abhresh Sugandhi

Author

Abhresh is specialized as a corporate trainer, He has a decade of experience in technical training blended with virtual webinars and instructor-led session created courses, tutorials, and articles for organizations. He is also the founder of Nikasio.com, which offers multiple services in technical training, project consulting, content development, etc.

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The event handling in react is declarative and the advantage of declarative way to handlers is that they are part of the User interface structure.  Let’s take a look at event handling in class components                       Import React, { Component } from ‘...react’                         class TestApp extends Component {                              clickHandler() {                                  console.log(“clicked”)                                }                                render(){                                      return(                                                                                     Click me                                                                                 )                                 }                            }                       export default TestApp You cannot return false to prevent default behaviour in React. You must call preventDefault explicitly.  In HTML it looks like below:    Click Output: It will print “Clicked”  And in React, like this:  function clickHandle(e) {       e.preventDefault();       console.log(“Handled”);   }  Click  Output : console will print “Handled”  There are some  event handlers triggered by an event in the bubbling phase which is the same as with the normal DOM API; simply attach a handler to an eventual parent of an element and any events triggered on that element will bubble to the parent as long as it's not stopped via stopPropagation along the way   Click me  Below are some of the event handlers triggered in the bubbling phase:  MouseEvents           onClick           onDrag          onDoubleClick Keyboard Events                    onKeyDown                    onKeyPress                    onKeyUp Focus Events                  onFocus   onBlur To capture an event handler for the capture phase, append capture to the event name. For example, instead of using onClick, use onClickCapture to handle the click event.  Capture event example:                  Click me    Additional ExamplesExample1                       Import React from ‘...react’                         function clickAppHandler() {                                function clickHandler() {                                        console.log(‘clicked’)                                         }                                  return (                                                                                  Click                                                                          )                         }                       export default clickAppHandler   Example2       This example is along with HTML in a single file                                                            Events                               function testApp (){                        alert((“Hello Event”);                                                   test Clicked                  test double Clicked                     Adding Events: Below example is how you add an event. Highlighted in bold                      Import React from ‘...react’                         function clickAppHandler() {                                function clickHandler() {                                        console.log(‘clicked’)                                         }                                  return (                                                                                  Click                                                                          )                         }                       export default clickAppHandler  Passing Arguments to Event HandlerThere are two ways arguments are passed to event handler  Arrow function                    this.handleClick(id,e)}>Click                onClick is the event                e is the event object                 id can be state or props or some data Bind method      Click  In this case event object is automatically passed In both methods e represents the react event and its passed after the ID as second argument,With an arrow function this event e is passed explicitly but with bind method its automatically passed.                                     Import React,{ Component } from “react”;                                         class TestApp extends Component {                                           state = {                                                       id: 2,                                                      Name: “TestApp Dummy”                                                };                                                             //arrow function                                                 handleClick = (id,e) => {                                                       console.log(id);                                                       console.log(e);                                                  };                                               handleArg = (e) => { this.handleClick(this.state.id,e);}                                                          render() {     return (                    TestApp,{this.state.name}            onClick={this.handleArg}>Display            );   }  }  The react event is an object and obtained from react. Instead of creating a separate function for passing argument, you can directly pass the anonymous arrow function as shown in the render function below:     render() {        return (                                                                                                       TestApp,{this.state.name}                                                {                           this.handleClick(this.state.id,e);                                                               }}>Display                                                                                                         );                                                 }                                            }    Output:   click on button  “TestApp Dummy “                   Let’s see only how bind method looks like in the render function    render() {                                         return (                                                                                                 TestApp,{this.state.name}                                                   Display                                                                                                       );                                                  }                                              } Output: this will display the h1 tag and when you click the button handleClick function gets invoked and the console will display id of the state object as shown above. Building a Practice to Thoroughly Understand Events This blog focuses on event handling, which in turn teaches about event handlers declared in JSX markup.This approach helps in tracking down the element mapped with events in an easy way.  We also learned how to handle multiple event handlers in a single element by using JSX attributes.we also learned about ways to bind event handler and  parameter values. Then we learned about synthetic events which are abstractions around native events. The best way you can retain this learning is by practicing more and tackling the complexities that may arise as you practice. You can find several tutorials on the internet or share your questions with us here. Happy learning! 
5355
Handling React Events - A Detailed Guide

Event handling essentially allows the user to inte... Read More

MongoDB Query Document Using Find() With Example

MongoDB's find() method selects documents from a collection or view and returns a cursor to those documents. There are two parameters in this formula: query and projection.Query – This is an optional parameter that specifies the criteria for selection. In simple terms, a query is what you want to search for within a collection.Projection – This is an optional parameter that specifies what should be returned if the query criteria are satisfied. In simple terms, it is a type of decision-making that is based on a set of criteria.MongoDB's Flexible SchemaA NoSQL database, which stands for "not only SQL," is a way of storing and retrieving data that is different from relational databases' traditional table structures (RDBMS).When storing large amounts of unstructured data with changing schemas, NoSQL databases are indeed a better option than RDBMS. Horizontal scaling properties of NoSQL databases allow them to store and process large amounts of data.These are intended for storing, retrieving, and managing document-oriented data, which is frequently stored in JSON format (JavaScript Object Notation). Document databases, unlike RDBMSs, have a flexible schema that is defined by the contents of the documents.MongoDB is one of the most widely used open-source NoSQL document databases. MongoDB is known as a 'schemaless' database because it does not impose a specific structure on documents in a collection.MongoDB is compatible with a number of popular programming languages. It also offers a high level of operational flexibility because it scales well horizontally, allowing data to be spread or 'sharded' across multiple commodity servers with the ability to add more servers as needed. MongoDB can be run on a variety of platforms, including developer laptops, private clouds, and public clouds.Querying documents using find()MongoDB queries are used to retrieve or fetch data from a MongoDB database. When running a query, you can use criteria or conditions to retrieve specific data from the database.The function db.collection is provided by MongoDB. find() is a function that retrieves documents from a MongoDB database.In MongoDB, the find method is used to retrieve a specific document from the MongoDB collection. In Mongo DB, there are a total of six methods for retrieving specific records.find()findAndModify()findOne()findOneAndDelete()findOneAndReplace()findOneAndUpdate()Syntax:find(query, projection)We can fetch a specific record using the Find method, which has two parameters. If these two parameters are omitted, the find method will return all of the documents in the MongoDB collection.Example:Consider an example of employees with the database of employee_id and employee_name and we will fetch the documents using find() method.First, create a database with the name “employees” with the following code:use employeesNow, create a collection “employee” with:db.createCollection("employee")In the next step we will insert the documents in the database:db.employee.insert([{employee_id: 101, employee_name: "Ishan"}, {employee_id: 102, employee_name: "Bhavesh"}, {employee_id: 103, employee_name: "Madan"}])Find all Documents:To get all the records in a collection, we need to use the find method with an empty parameter. In other words, when we need all the records, we will not use any parameters.db.employee.find()Output in Mongo ShellThe pretty() method can be used to display the results in a formatted manner.Syntax:db.COLLECTION_NAME.find().pretty()Let’s check our documents with pretty() method:Query FiltersWe will see examples of query operations using the db.collection.find() method in mongosh.We will use the employee collection in the employees database.db.employee.insert([{employee_id: 101, employee_name: "Ishan", age: 21, email_id: "ishanjain@gmail.com"}, {employee_id: 102, employee_name: "Bhavesh", age: 22, email_id: "bhaveshg@gmail.com"}, {employee_id: 103, employee_name: "Madan", age: 23, email_id: "madan@gmail.com"}])As we have seen earlier that to select all the documents in the database we pass an empty document as the query filter parameter to the find method.db.employee.find().pretty()Find the first document in a collection:db.employee.findOne()Find a document by ID:db.employee.findOne({_id : ObjectId("61d1ae0b56b92c20b423a5a7")})Find Documents that Match Query Criteriadb.employee.find({“age”: “22”})db.employee.find({"employee_name": "Madan"}).pretty()Sort Results by a Field:db.employee.find().sort({age: 1}).pretty()order by age, in ascending orderdb.employee.find().sort({age: -1}).pretty()order by age, in descending orderAND Conditions:A compound query can specify conditions for multiple fields in the documents in a collection. A logical AND conjunction connects the clauses of a compound query indirectly, allowing the query to select all documents in the collection that meet the specified conditions.In the following example, we will consider all the documents in the employee collection where employee_id equals 101 and age equals 21.db.employee.find({"employee_id": 101, "age": "21" }).pretty()Querying nested fieldsThe embedded or nested document feature in MongoDB is a useful feature. Embedded documents, also known as nested documents, are documents that contain other documents.You can simply embed a document inside another document in MongoDB. Documents are defined in the mongo shell using curly braces (), and field-value pairs are contained within these curly braces.Using curly braces, we can now embed or set another document inside these fields, which can include field-value pairs or another sub-document.Syntax:{ field: { field1: value1, field2: value2 } }Example:We have a database “nested” and in this database we have collection “nesteddoc”.The following documents will insert into the nesteddoc collection.db.nesteddoc.insertMany([ { "_id" : 1, "dept" : "A", "item" : { "sku" : "101", "color" : "red" }, "sizes" : [ "S", "M" ] }, { "_id" : 2, "dept" : "A", "item" : { "sku" : "102", "color" : "blue" }, "sizes" : [ "M", "L" ] }, { "_id" : 3, "dept" : "B", "item" : { "sku" : "103", "color" : "blue" }, "sizes" : "S" }, { "_id" : 4, "dept" : "A", "item" : { "sku" : "104", "color" : "black" }, "sizes" : [ "S" ] } ])Place the documents in the collection now. Also, take a look at the results:As a result, the nesteddoc collection contains four documents, each of which contains nested documents. The find() method can be used to access the collection's documents.db.nesteddoc.find()Specify Equality Condition:In this example, we will select the document from the nesteddoc query where dept equals “A”.db.nesteddoc.find({dept: "A"})Querying ArraysUse the query document {: } to specify an equality condition on an array, where is the exact array to match, including the order of the elements.The following query looks for all documents where the field tags value is an array with exactly two elements, "S" and "M," in the order specified:db.nesteddoc.find( { sizes: ["S", "M"] } )Use the $all operator to find an array that contains both the elements "S" and "M," regardless of order or other elements in the array:db.nested.find( { sizes: { $all: ["S", "M"] } } )Query an Array for an Element:The following example queries for all documents where size is an array that contains the string “S” as one of its elements:db.nesteddoc.find( { sizes: "S" } )Filter conditionsTo discuss the filter conditions, we will consider a situation that elaborates this. We will start by creating a collection with the name “products” and then add the documents to it.db.products.insertMany([ { _id: 1, item: { name: "ab", code: "123" }, qty: 15, tags: [ "A", "B", "C" ] }, { _id: 2, item: { name: "cd", code: "123" }, qty: 20, tags: [ "B" ] }, { _id: 3, item: { name: "ij", code: "456" }, qty: 25, tags: [ "A", "B" ] }, { _id: 4, item: { name: "xy", code: "456" }, qty: 30, tags: [ "B", "A" ] }, { _id: 5, item: { name: "mn", code: "000" }, qty: 20, tags: [ [ "A", "B" ], "C" ] }])To check the documents, use db.products.find():$gt$gt selects documents with a field value greater than (or equal to) the specified value.db.products.find( { qty: { $gt: “20” } } )$gte:$gte finds documents in which a field's value is greater than or equal to (i.e. >=) a specified value (e.g. value.)db.products.find( { qty: { $gte: 20 } } )$lt:$lt selects documents whose field value is less than (or equal to) the specified value.db.products.find( { qty: { $lt: 25 } } )$lte:$lte selects documents in which the field's value is less than or equal to (i.e. =) the specified value.db.products.find( { qty: { $lte: 20 } } )Query an Array by Array Length:To find arrays with a specific number of elements, use the $size operator. For example, the following selects documents with two elements in the array.db.products.find( { "tags": {$size: 2} } )ProjectionIn MongoDB, projection refers to selecting only the data that is required rather than the entire document's data. If a document has five fields and you only want to show three of them, select only three of them.The find() method in MongoDB accepts a second optional parameter, which is a list of fields to retrieve, as explained in MongoDB Query Document. When you use the find() method in MongoDB, it displays all of a document's fields. To prevent this, create a list of fields with the values 1 or 0. The value 1 indicates that the field should be visible, while 0 indicates that it should be hidden.Syntax:db.COLLECTION_NAME.find({},{KEY:1})Example:We will consider the previous example of products collection. Run the below command on mongoshell to learn how projection works:db.products.find({},{"tags":1, _id:0})Keep in mind that the _id field is always displayed while executing the find() method; if you do not want this field to be displayed, set it to 0.Optimized FindingsTo retrieve a document from a MongoDB collection, use the Find method.Using the Find method, we can retrieve specific documents as well as the fields that we require. Other find methods can also be used to retrieve specific documents based on our needs.By inserting array elements into the query, we can retrieve specific elements or documents. To retrieve data for array elements from the collection in MongoDB, we can use multiple query operators.
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MongoDB Query Document Using Find() With Example

MongoDB's find() method selects documents from a c... Read More

Implementing MongoDb Map Reduce using Aggregation

Algorithms and applications in today's data-driven market collect data about people, processes, systems, and organisations 24 hours a day, seven days a week, resulting in massive amounts of data. The problem is figuring out how to process this massive amount of data efficiently without sacrificing valuable insights.What is Map Reduce? The MapReduce programming model comes to the rescue here. MapReduce, which was first used by Google to analyse its search results, has grown in popularity due to its ability to split and process terabytes of data in parallel, generating results faster. A (Key,value) pair is the basic unit of information in MapReduce. Before feeding the data to the MapReduce model, all types of structured and unstructured data must be translated to this basic unit. The MapReduce model, as the name implies, consists of two distinct routines: the Map-function and the Reduce-function.  MapReduce is a framework for handling parallelizable problems across huge files using a huge number of devices (nodes), which are collectively referred to as a cluster (if all nodes are on the same local network and use similar hardware) or a grid (if the nodes are shared across geographically and administratively distributed systems, and use more heterogeneous hardware).  When data stored in a filesystem (unstructured) or a database(structured) is processed, MapReduce can take advantage of data's locality, processing it close to where it's stored to reduce communication costs. Typically, a MapReduce framework (or system) consists of three operations: Map: Each worker node applies the map function to local data and saves the result to a temporary storage. Only one copy of the redundant input data is processed by a master node. Shuffle: worker nodes redistribute data based on output keys (produced by the map function), ensuring that all data associated with a single key is stored on the same worker node. Reduce: each group of output data is now processed in parallel by worker nodes, per key. This article will walk you through the Map-Reduce model's functionality step by step. Map Reduce in MongoDB The map-reduce operation has been deprecated since MongoDB 5.0. An aggregation pipeline outperforms a map-reduce operation in terms of performance and usability. Aggregation pipeline operators like $group, $merge, and others can be used to rewrite map-reduce operations. Starting with version 4.4, MongoDB provides the $accumulator and $function aggregation operators for map-reduce operations that require custom functionality. In JavaScript, use these operators to create custom aggregation expressions. The map and reduce functions are the two main functions here. As a result, the data is independently mapped and reduced in different spaces before being combined in the function and saved to the specified new collection. This mapReduce() function was designed to work with large data sets only. You can perform aggregation operations like max and avg on data using Map Reduce, which is similar to groupBy in SQL. It works independently and in parallel on data. Implementing Map Reduce with Mongosh (MongoDB Shell)  The db.collection.mapReduce() method in mongosh is a wrapper for the mapReduce command. The examples that follow make use of the db.collection.mapReduce(). Example: Create a collection ‘orders’ with these documents: db.orders.insertMany([     { _id: 1, cust_id: "Ishan Jain", ord_date: new Date("2021-11-01"), price: 25, items: [ { sku: "oranges", qty: 5, price: 2.5 }, { sku: "apples", qty: 5, price: 2.5 } ], status: "A" },     { _id: 2, cust_id: "Ishan Jain", ord_date: new Date("2021-11-08"), price: 70, items: [ { sku: "oranges", qty: 8, price: 2.5 }, { sku: "chocolates", qty: 5, price: 10 } ], status: "A" },     { _id: 3, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-08"), price: 50, items: [ { sku: "oranges", qty: 10, price: 2.5 }, { sku: "pears", qty: 10, price: 2.5 } ], status: "A" },     { _id: 4, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-18"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 5, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-19"), price: 50, items: [ { sku: "chocolates", qty: 5, price: 10 } ], status: "A"},     { _id: 6, cust_id: "Madan Parmar", ord_date: new Date("2021-11-19"), price: 35, items: [ { sku: "carrots", qty: 10, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },     { _id: 7, cust_id: "Madan Parmar", ord_date: new Date("2021-11-20"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 8, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 75, items: [ { sku: "chocolates", qty: 5, price: 10 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },     { _id: 9, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 55, items: [ { sku: "carrots", qty: 5, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 }, { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 10, cust_id: "Abhresh", ord_date: new Date("2021-11-23"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }  ]) Apply a map-reduce operation to the orders collection to group them by cust_id, then add the prices for each cust_id: To process each input document, define the map function: this refers the document that the map-reduce operation is processing in the function. For each document, the function maps the price to the cust_id and outputs the cust_id and price. var mapFunction1 = function() {emit(this.cust_id, this.price);}; With the two arguments keyCustId and valuesPrices, define the corresponding reduce function: The elements of the valuesPrices array are the price values emitted by the map function, grouped by keyCustId. The valuesPrice array is reduced to the sum of its elements by this function. var reduceFunction1 = function(keyCustId, valuesPrices) {return Array.sum(valuesPrices);};Apply the mapFunction1 map function and the reduceFunction1 reduce function to all documents in the orders collection: db.orders.mapReduce(mapFunction1,reduceFunction1,{ out: "map_reduce_example" }) The results of this operation are saved in the map_reduce_example collection. If the map_reduce_example collection already exists, the operation will overwrite its contents with the map-reduce operation's results. Check the map_reduce_example collection to verify: db.map_reduce_example.find().sort( { _id: 1 } ) Aggregation Alternative:You can rewrite the map-reduce operation without defining custom functions by using the available aggregation pipeline operators: db.orders.aggregate([{$group: { _id:"$cust_id",value:{$sum: "$price" } } },{ $out: "agg_alternative_1" }]) Check the agg_alternative_1 collection to verify: db.agg_alternative_1.find().sort( { _id: 1 } )Implementing Map Reduce with Java Consider the collection car and insert the following documents in it. db.car.insert( [ {car_id:"c1",name:"Audi",color:"Black",cno:"H110",mfdcountry:"Germany",speed:72,price:11.25}, {car_id:"c2",name:"Polo",color:"White",cno:"H111",mfdcountry:"Japan",speed:65,price:8.5}, {car_id:"c3",name:"Alto",color:"Silver",cno:"H112",mfdcountry:"India",speed:53,price:4.5}, {car_id:"c4",name:"Santro",color:"Grey",cno:"H113",mfdcountry:"Sweden",speed:89,price:3.5} , {car_id:"c5",name:"Zen",color:"Blue",cno:"H114",mfdcountry:"Denmark",speed:94,price:6.5} ] ) You will get an output like this:  Let's now write the map reduce function on a collection of cars, grouping them by speed and classifying them as overspeed cars.  var speedmap = function (){  var criteria;  if ( this.speed > 70 ) {criteria = 'overspeed';emit(criteria,this.speed);}}; Based on the speed, this function classifies the vehicle as an overspeed vehicle. The term "this" refers to the current document that requires map reduction. var avgspeed_reducemap = function(key, speed) {       var total =0;       for (var i = 0; i 
7344
Implementing MongoDb Map Reduce using Aggregation

Algorithms and applications in today's data-driven... Read More