The Engineering Projects

Introduction to Proteus

Hello readers, I hope you all are doing great. In today's tutorial, I am going to share a detailed Introduction to Proteus. It's our first tutorial in Proteus series. Today's tutorial is for beginners but still I would suggest you to read it once, as I am going to explain why Proteus? Throughout our Engineering Course, we have to design a lot of electronics or embedded circuits and it's always a best approach to simulate these circuits first on some simulation software i.e. Proteus, PSPice etc., before assembling them on actual hardware. Among these simulation software, Proteus is my favorite one so let's get started with detailed Introduction to Proteus:

Introduction to Proteus ISIS

• Proteus Design Suite (designed by Labcenter Electronics Ltd.) is a software tool set, mainly used for creating schematics, simulating Electronics & Embedded Circuits and designing PCB Layouts.
• Proteus ISIS is used by Engineering students & professionals to create schematics & simulations of different electronic circuits.
• Proteus ARES is used for designing PCB Layouts of electronic circuits.
• It's available in four languages i.e. English, Chinese, Spanish & French.

Why use Proteus ?

"Our circuit is working perfectly on Proteus but when we have implemented it on hardware, it's not working." I receive a lot of such questions from engineering students, that's why, I am explaining what's the real purpose of Proteus:

• Proteus is quite lenient in circuit designing and it works on ideal conditions i.e. if you don't add pull up resistors in Proteus simulation, then it won't give garbage value.
• Proteus is also used for PCB designing, we use Proteus ARES for that. ( We will discuss it in upcoming lectures )

So, when I am working on some electronics circuit, then I first design the simulation on Proteus ISIS and once I got sure that everything's working fine then I design its circuit on either the vero board or the bread board and again I perform some real world testing & when I got sure that my circuit is fully working then I design its PCB in Proteus ARES.

• Proteus is also used for designing/testing programming codes for different Microcontrollers i.e. Arduino, PIC Microcontroller, 8051 etc.

In Embedded projects, we need to design a programming code for Microcontrollers and for designing such codes you have to perform a lot of testing, which involves uploading code to Microcontroller. So, in such projects, Proteus is a great relief. Let's say, you have to print some strings on 20x4 LCD, then its quite annoying to burn the Microcontroller several times for typographical errors. Instead, design a circuit in Proteus and test your code in the simulation and once you are sure that you are getting perfect output then burn your PIC Microcontroller and test it on real hardware. Quite easy and handy. In the coming classes, I will show you how to burn code in Microcontrollers in Proteus. Note: In code testing, there's again a possibility that you get different results in real hardware but its quite rare and mostly happens in delay functions.

Getting Started With Proteus

You can download Proteus software from it's official website and you should also read How to Download & Install Proteus software. So now I hope you have installed Proteus and ready to work on it:

• Click on Proteus ISIS and it will open up as shown in below image.
• In the central area surrounded by blue lines, we design our circuit i.e. place the components and then join them together.

• As you can see in above figure that we have a lot of icons in Proteus software, so let's first understand these sections one by one.
• In the below image, I have divided the Proteus font-end in four sections:

• Section 1 is a toolbar which you would have seen on many simulation software, it has simple functionalities i.e. first icon to create a new layout, second one to open an existing layout, next one is to save layout, then there comes few zooming options and few other tools which we will discuss in coming tutorials.
• Section 2 has two buttons. P is used to open the components list and E is used for editing purposes, like you want to edit the properties of any component then simply click on that component and then click on E and it will open the properties of that component and you can easily edit it.
• Section 3 has different tools, used for designing circuits, we will discuss them in detail, at the end of today's tutorial.
• Section 4 is the remote control section of Proteus, as it contains four buttons i.e. Play, Step, Pause & Stop. In order to run the simulation, we have to click on this play button.

Component Selection in Proteus ISIS

• As shown in below image, click on the icon that says Click # 1, it's a Component Mode Icon.
• After that click on P button and a new window will open up named Pick Devices.

• In this new window there's a textbox on which Keyword is written, this text box is used for the component search.
• Proteus database has unlimited components in it so now in order to get your desired component, you have to search for it as I did.
• I have searched for PIC16F877A and Proteus provided me that component along with its preview in top right corner and PCB package ( if available ). Unfortunately, my Proteus doesn't have the PCB preview of PIC16F877A that's why it's blank.
• In order to add the component in Proteus workspace, either double click on it or click on the OK button.

Instruments in Proteus ISIS

• There are few measuring instruments available in Proteus, which you can open by clicking the Instruments Icon, as shown in figure on right side.
• First one is oscilloscope, we use it for viewing the behavior of different signals generated.
• Another important instrument is Virtual Terminal, it is shown on the fourth number. This Virtual Terminal is used for checking data coming through Serial Port.
• Then there's Signal Generator, it is used to generate signal like sine wave of desired frequency.
• We also have Voltmeter & Ammeter for both AC & DC.
• We will discuss them in detail in our coming lectures.
• As you can see in figure on right side, Icon A is called Graph mode, used to create graphs of voltage and current. It has different style of graphs.
• Icon B and C are voltage and current probes respectively. Suppose you have designed some circuit in Proteus and you want to check the value of voltage at any point in the circuit. In order to do so, simply select this voltage probe and place it there and when you run your circuit, the probe will show the value of voltage above it and same for current probe.
• Icon D is used when we want to design our own component in Proteus.
• Icon E is a simple text editor, used for placing labels, warning or components names etc.

So, that was all for today. I hope you have enjoyed this detailed Introduction to Proteus. If you have any question, feel free to ask in comments and also subscribe through email to our mailing list, so that you don't miss any part of this tutorial series. Stay blessed. Take care.

DbContext Class in Entity Framework Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at what is DbContext Class in Entity Framework Core. It's our 17th tutorial in ASP.NET Core series. In our previous tutorial, we have discussed Entity Framework Core in detail and have also installed it in our web application. So, now we need understand how to work with Entity Framework Core and for that we have to look at its classes & functions. So, today we will discuss one of its class named DBContext in detail:

DbContext Class in Entity Framework Core

• EF Core contains an important class named DbContext, which is mainly responsible for communication between Database & software objects.
• We communicate with our database using this DbContext class and we can also map our fetched data to software objects i.e. properties.

• So, in order to use this DbContext class, we have to create a new class and then inherit it from DbContext Class.
• When we inherit our new class from DBContext Class, then we will be able to call all its members from our new class.
• So, I am going to create a new class in Models folder, as Models are going to communicate with the database.
• I have named this class TepDbContext and have inherited it from DbContext class, as shown in figure on right side.

DbContextOptions class in EF Core

• DbContextOptions class in EF Core contains all the configuration information about database i.e. database name, database provider, database connection string etc.
• We need to use DbContextOptions class along with DbContext class, so let's create a Constructor of DBContext class, as shown in below figure:

• You can see in above figure that I have created a constructor of TEPDbContext class and then instantiated DbContextOptions class as a parameter.
• After that, I have provided TepDbContext as a parameter inside < >, thus this option class is applied to our newly created TepDbContext class.
• Next, I have created its object titled options and finally called the base constructor from DBContext class and provided this options object as a parameter.

DbSet Property in EF Core

• So far, we have discussed two classes from EF Core and now it's time to have a look at this property in EF Core titled DBSet.
• DBSet Property is used to map the data from software objects to underlying database.
• Currently, we have just Engineers.cs file, which has the data properties, that need to be stored in our database.
• So, let's create a new property in our TepDBContext class named DBSet, as shown in below figure:

• As you can see we have created a new DbSet Property of type Engineers and given it a name DbEngineers. ( We will use it later )

So, we have successfully created our TepDbContext class and have updated it, so, now its time to register this newly created class with dependency injection of ASP.NET Core.

Database Connection String in App Settings

• We need to provide authentication settings for our database, which we will add in appsettings.json file, so that we could use it anywhere in our project.
• I am using MySQL database and thus provided its connection string, as shown in below figure:

• You can see in above code that I have created a new section named ConnectionStrings and inside it, I have create DbConnection variable and have assigned DB connection string to it.
• In the connection string, I have first provided the server i.e. localdb and then provided name of the database i.e. TepDB and finally I have declared it a trusted connection.
• This MSSQLLocalDB is already available in Visual Studio and we will discuss it in detail in our coming lectures.
• When we upload our web application on a real server then we will change these server settings but for now, we will use localdb available.

Dependency Injection for DbContext class

• We have studied Dependency Injection in ASP.NET Core in detail, so now let's register TepDbContext class & provide SQL database connection string using Dependency Injection
• For that, open your startup.cs file and in ConfigureServices method, on IServicesCollection instance, we have called AddDbContextPool method, as shown in below figure:

• We have also specidified that we are using SQL Server & have provided the database connection string as well, I have placed a red boundary across it.
• In order to get the Connection string from appsettings.json file, I have injected IConfiguration using Constructor Injection and have placed a green boundary across it.
• So, our TepDBContext class is now registered with ASP.NET Core and we have also specified the Database provider & Connection String.

So, that was all for today. We have completed all our settings for database but we haven't yet created it. So, in our next lecture, we will see How to Create Database using EF Core Migrations. Till then take care & have fun !!!

Introduction to JavaScript

Hello folks, I hope you are having a great day. Today, I am going to start this new tutorial series on JavaScript and here's our 1st tutorial titled Introduction to JavaScript. This is a beginner level tutorial series, where we will start from very basics & will slowly move towards complex concepts. If you're not a beginner or looking for secure development training or advanced tutorials, stay tuned, more training is coming. We can use any development Editor for running JavaScript and for this tutorial series, I will use Microsoft Visual Studio Code, which is free to use & you can download it from official site. You don't need to be an expert programmer, in order to learn JavaScript, but you must have some basic knowledge of HTML & CSS. So, let's get started with today's lecture:

What is JavaScript - A Quick Definition

• JavaScript ( initially named as LiveScript, officially named as ECMAScript ) is a client-side scripting language, developed by Brendan Eich in 1995 and is used to create interactive webpages and mostly used in game development.
• Before JavaScript, webpages were dull and has no way to interact with the user, as we had only server side languages ( php, java etc. ) at that time and in order to get any action done, we have to send request to the server.

• With JavaScript, now we can perform any complex task without refreshing the page, JavaScript works on client side that's why there's no need of page refreshing.
• You must have noticed on your Facebook / Twitter profile that they update automatically, that's because of JavaScript.
• As JavaScript is a client side language so it can't communicate directly with the server i.e. database or file system.
• JavaScript is normally confused with Java, but they are two entirely different languages, Java is server side complex language while JavaScript is a simple scripting language.

How to Run JavaScript Code?

• As I mentioned earlier, JavaScript is a client side scripting language, so we don't need any compiler or editor for running JavaScript.
• Instead, JavaScript is directly executed by the web Browsers, similar to HTML & CSS, which are also client side languages.
• When a user makes an HTTP request, then browser reads the webpage and along with HTML,CSS etc. it also finds the JS scripts and executes them.
• All modern browsers support JavaScript and you can enable / disable JavaScript in your browser's settings.
• Moreover, JavaScript works on almost all operating platforms i.e. Windows, Linux, Mac, Ubuntu etc.
• So, in order to run JavaScript, you can use any Programming Environment / Editor i.e. Sublime, Notepad++, Visual Studio Code etc.

Uses of JavaScript

So, now let's have a look at few uses / advantages of Javascript:

1. Developing Mobile Applications & Games.
2. Web Browser-based Games.
3. Add interaction to websites.
4. Back end web Development.
5. Rich interface for Applications and web pages.

How to Include a JavaScript Code in HTML WebPage

• As I have mentioned earlier, we don't need any editor to run or execute JavaScript. Instead, web browsers execute the JS code on their own.
• But question is, How web Browsers are going to recognize that its a JS code ??
• And the answer is, the code placed between <script> </script> tags will be treated as a JavaScript Code.
• There are two ways to include the JavaScript code in an HTML webpage, discussed as follows:

Embedding JavaScript Code directly in HTML Page

• When we add JavaScript directly in <body> tag of our HTML page, it is termed as Embedded JavaScript.
• In our HTML page, we can place JavaScript Code in the <script> </script> tags, as shown in the figure:
• You can see in the figure that I have added a simple JavaScript Code:

<script> alert(“I am learning JavaScript”);    </script>

• To run this code you have to add an extension. Go to the left side of visual studio and click on extension or press Ctrl + Shift + X buttons. 
• Afterwards, Search “Open in browser” and install the first file. Look below in the image for more detail.
• When your exertion is installed, now go back to your HTML file and press Alt + B.  It will run your code. 
• You will see something similar to below image, in your browser.
• This is a simple JavaScript alert message, displaying our content.

Include External JavaScript File in HTML WebPage

• If we add JavaScript Code directly in HTML page then it will make the code quite messy.
• So, it's always a best practice to create a separate file for JavaScript ( extension .js ) and then include this file in your webpage.
• By convention, If your JavaScript code is more than 10 lines, then it's better to add an external JavaScript file.
• It also reduces the code repetition i.e. if you are using your JS code for multiple pages.
• Let's see now, how to add an external JavaScript file:

Steps to Follow:

• Create a new file by pressing Ctrl + N and add  “alert("Introduction to JavaScript");”  content in this file. Save it with the name “Test.js”.
• As you can see on the right side in the figure.
• Now go back to the “index.html” file and add the code as you can see in below figure:
• When you will refresh the web browser then it will automatically reload a JS file through source code, as shown in below figure:

What Is The Best Way To Include JavaScript File in Html

• You can add <script> tag in the <head> section of your HTML file, in the start of the <body> tag and also at the start or end of the body tag.
• But I would advise you to add it at the end of the <body> tag. I will show you why it should be at the bottom of the body tag.
• The HTML page always loads from top to bottom. And if your JS file will be in <head> tag or opening of the <body> tag. Therefore, it’s gonna run JavaScript first before loading any of the content in and it will leave a negative impact on your webpage. Let me show you now how it will drop a negative impression on your website.
• Here is a basic example for you. As you can see in below image that I have added <script> tag at the start of <head> tag and add a new tag of <h1> for your understanding.
• Save these file and press ALT + B to execute this code. You will notice that as you see in the picture underneath that only <script> tag alert comes up first without loading the rest of page.
• But once I click at ok then it has loaded the rest of the page now. As indicated in the image here.

 

• It leaves a bad impact on users because the page is loading step by step but not at once. Now I am gonna add  <script> at the bottom of the <body> tag and as you can see in image down.
• Now save it go again to the browser and reload the page.  Instantly you can see the content and alert form at the same time. This is a perfect way of adding JS.

I am sure you all already know HTML and CSS but you have attempted to learn JavaScript many times but failed for some reason and you drop it. But I am sure now you are going to stick with me since I am going to describe you step by step each code. From the next lesson onward, I am going to tell you more in detail what is the Syntax of JavaScript and where to place JavaScript file. I hope you guys understand this lesson and I will see you in my next tutorial. Till then take care of yourself. If YOU have any question regarding this post feel free to comment below and ask about it.  I will definitely reply to your query as soon as possible. 

How to perform Software Testing and Debugging

Hello everyone, I hope you are having a fine day. In today’s tutorial, I am going to discuss “Software Testing and Debugging”

During testing and debugging, seek advice for the various techniques of detecting and eliminating mistakes in a program, so that it produces the desired result. Every programmer needs to be aware of the truth that a program does not always run perfectly for the first time. It is consequently vital to make efforts in case you do stumble on the errors. First, determine and note any errors which are found during the very first building and running of the program.

Errors that Occur during Initialization of the Program

Many errors can occur when running a program, some apparent, and others are not. All these mistakes can be grouped under four types, namely: syntax errors, run-time errors, logical mistakes, and latent mistakes.

Syntax problems are any violation of regulations specified within a  programming language results in syntax mistakes. The compiler during the build and run process of the code will automatically define such errors. When syntax errors are found in the source code of the program, the compilation fails and terminates after listing the errors and the line numbers within the source code of the application where the errors have occurred. 

Remember, in a few cases, the line quantity won't precisely suggest the vicinity of the mistake. In different instances, syntax error can also result in an extended listing of mistakes. Correction of one of the mistakes at the beginning of the build of the system may also take away the entire listing.

Run-time mistakes  include mismatch of data types or referencing out-of-variety array details, go undetected by the compiler. An application with those mistakes will run. However, it produces misguided consequences. It should be noted that isolating run-time blunders is usually a hard challenge.

Logical errors: As the name suggests, these mistakes are related to the common sense of program execution. Such moves as taking a wrong direction, failure to forget a particular situation, and incorrect order of assessment of statements belong to this category. Logical mistakes do now not show up as collect-generated mistakes messages. Rather, the program outputs the wrong results during execution. These errors are due to adverse information and incorrect translation of the set of rules by the program.

Latent errors are a 'hidden' error that pops up when a particular set of information is used — for instance, subsequent declaration.

Various Ways of  Testing a Program

Testing is the process of reviewing and executing a program to detect mistakes, which can belong to any of the four types mentioned above. We know that while the compiler can locate syntactic and semantic errors, it can't come across run-time and logical mistakes that show up all through the execution of the program. Testing, therefore, should include vital steps to detect all viable mistakes in the software. It is important to remember that it is miles impractical to find all the mistakes. The testing procedure can also encompass the subsequent two degrees:

• Human testing
• Computer-based trying out

Human checking out is a powerful error-detection procedure and finishes earlier than the computer-based tryout. Human testing methods encompass code inspection by the programmer, code inspection with the aid of a test institution, and a review by an essay writing service or a peer organization. The test is achieved through a statement and is analyzed with a tick list of common programming mistakes. In addition to finding the errors, the programming style and preference of algorithms are also reviewed.

Computer-based testing entails a list of degrees, particularly the compiler tryout and run-time check out. Compiler testing is the most effective of the two and also detects undiscovered syntax errors. The software executes while the compiler detects greater mistakes. 

Should this mean that this system is correct? Will it produce the expected consequences? The answer is no. The software might comprise both run-time and logical errors, which in any case won't affect the compiling process of the program.

Program Debugging And Error Checking 

Debugging is the process of discovering and correcting the mistakes in a program’s source code. One simple technique of debugging is locating print statements or logs output by the compiler during the build process of the system that shows the values of variables. It displays the dynamics of a program and allows us to observe and compare statistics at various points. Once the area of a blunder is recognized and is error corrected, the debugging statements may be eliminated. We can use the conditional compilation statements, to switch on or off the debugging statements.

Another method is to use the technique of deduction. The area of a blunder is arrived at by the use of elimination and refinement. It is done through the listing of possible reasons for the mistake.

In Conclusion

Two critical resources of a computer gadget are execution time and memory. The performance of an application is measured in phrases of those two sources. Efficiency can be progressed with true design and coding practices.

Thank you so much for reading this article. If you have any question regarding this article, you can comment below and ask us. We are looking forward for your feedback.

Introduction to Entity Framework Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at detailed Introduction to Entity Framework Core. It's our 16th tutorial in ASP.NET Core series. So far, we have covered the the MVC architecture and few concepts related to object oriented programming and now we are ready to get our hands on Databases. So, today we will cover data handling in detail, which is done by Entity Framework Core in .NET Core applications. So, let's first understand this Entity Framework Core:

Introduction to Entity Framework Core

• Entity Framework Core ( normally called EF Core ), designed by Microsoft, is an open source, flexible, extensible, lightweight and cross-platform framework, which is used for storing & retrieving data from database.
• EF Core creates a bridge between Objects in Programming & relational databases, thus referred as Object-Relational Mapper. ( O/RM )
• In simple words, EF Core acts as a middle layer between our .NET Core Application & database.
• EF Core is written from scratch for .NET Core, but also works with standard .NET 4.5+, and is an enhancement of ADO.NET.

Why need Entity Framework Core ?

• If you have worked on any database i.e. SQL, MYSQL, Oracle etc. then you must have the idea about query strings.
• In order to send or request data from these databases, we need to use query strings, which are normally quite lengthy and prone to errors.
• In order to avoid this direct interaction with databases using query strings, we have many third party frameworks which handle these underlying query strings themselves and provide programmers with easy programming methods to deal with the data.
• Entity Framework Core is an official data handling framework designed by Microsoft and works perfectly with ASP.NET Core.
• EF Core supports a wide range of relational database using third party libraries called database providers, we install these libraries as NuGet Packages.
• For example, if I want to work on SQL database, then I will install SQL NuGet Package, we will install one later.

EF Core Approach

• We can use two approaches in Entity Framework Core, which are:
  • Code First Approach
  • Database First Approach
• We have very limited support available for "Database First Approach" for now and we use this approach, when we already have the database. ( will cover it in future lectures )
• In Code First Approach, we design our database from scratch and using dbContext class, we transfer data from  app to database & vice versa.

EF Core Package

• Now we need to select the type of database i.e. SQL, MYSQL, Oracle etc., which we want to use for our web application, so I am going to use Sql Database.
• In order to use SQL Database with EF Core, we need to install its NuGet Package called Microsoft.EntityFrameworkCore.SqlServer.
• This NuGet package is actually the Database provider, so if you are using any other database i.e. MYSQL, then you need to install its NuGet Package. ( We will install one in the next section )
• SQL Server NuGet Package has a dependency on EF Core Relational Package called Microsoft.EntityFrameworkCore.Relational.
• Relational package contains the functionality, that are common in all relational databases i.e. SQL, MYSQL, Oracle etc.
• This relational package, in turn has a dependency on Main EF Core Package called Microsoft.EntityFrameworkCore.
• That's the main base EF Core NuGet Package that will enable EF Core on our web App.

How to Install Entity Framework Core

• Now, let's install EF Core on our web application, so right click on the Project's Name in Solution Explorer.
• Now click on Manage NuGet Packages, and NuGet Package Manager will open up.
• In the Browser tab, make a search for EntityFrameworkCore.SqlServer and you will get results, as shown in below figure:

• You can see in above figure that first one appeared in the search, is our required NuGet Package, so let's install this one.
• As this SQL NuGet Package has a dependency on Relational, which in turn has dependency on EF Core, so when we install SQL Server Package, the other two will automatically be installed by the Visual Studio.
• So, click on the Install Button and then accept the terms and this SQL Server NuGet Package will be installed.
• After complete installation, you need to open Dependencies in Solution Explorer, as shown in figure on right side.
• You will find Packages in Dependencies, so open it up and inside it you will find our SQL Server NuGet Package.
• Expand this SQL Server Package and you will find its dependencies i.e. Relational etc.
• So, we have successfully installed Entity Framework Core for SQL Database on our web app.

So, that was all for today. We have successfully installed EF Core on our web application but we haven't yet created our SQL Database. In the next video, we will have a look at DbContext Class in Entity Framework Core. Till then take care & have fun !!!

Form Validation in ASP.NET Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at Form Validation in ASP.NET Core. It's our 15th tutorial in ASP.NET Core series. In our previous lecture, we have created a Registration Form for our engineering website. But we haven't added any validations on the submitted data. So, even if users don't fill any boxes and just hit the Register Button, a new user will be created without any personal info. So, today we will place some checks on these text boxes to validate the user submitted data. So, let's get started with it:

Form Validation in ASP.NET Core

• Validations in ASP.NET Core are available in the form of attributes & Tag Helpers.
• Validation Attributes are applied on Properties in Model classes and validate the user submitted data.
• Validation Tag Helpers are used in Views and provide validation errors to the users.

• So, let's add few validations to our registration form and show errors, if inappropriate data is submitted.

Validation Attributes in ASP.NET Core

• ASP.NET Core has many builtin Validation Attributes to verify the incoming data, few of them are as follows:
  • [Required] : Value is required.
  • [Regular Expression] : Value must match the regular expression provided.
  • [Compare] : Compares two properties i.e. Verify Email.
  • [Range] : Value must lie between specified range.
  • [MinLength] : Specifies the value's minimum length.
  • [MaxLength] : Specifies the value's maximum length.
  • [DataType] : Value must be of specified datatype.
• So, let's apply few of these Validation Attributes on our Properties in Engineers.cs file, placed in Models folder.
• We have already linked these properties with text boxes using asp-for Tag Helper.
• So, open this file & in Engineers class, place these validation attribute before properties, as shown in below figure:

• As you can see in above figure that before Username property, I have used two validation attributes i.e. Required & MaxLength.
• I have set the MaxLength to 50 and have also added a custom ErrorMessage.
• On the Email property, I have used Required & RegularExpression, this expression will verify the email format.
• On the FullName property, I have used Display attribute (it's not a validation attribute), and changed the name to "Full Name", it will change the label of this text box.
• Moreover, I have also made my enums properties null-able, as you can see I have placed ? sign infrom of DeptEnum & UniEnum. ( We will see later why null-able)
• We have added the validation attributes on our properties and now let's place a check in our Home Controllers class using builtin validation property.

Check if Data is Valid

• So, open you HomeController.cs class placed in the Controllers Folder.
• In HomeController class, we need to place validation check on the Registration action method of [HTTPPost] type, as this method is going to execute on pressing the Register button.

• As you can see in above code, I have placed an IF loop and have placed a Boolean property in it called ModelState.IsValid.
• This Boolean property will return TRUE, if there's no validation error & will return FALSE, if there's any validation error appeared.
• So, if it's true then I have added the submitted user data and displayed it in Info link by redirecting it to Info action method and if its FALSE, then simply returned the Registration View itself.
• One more thing to note here is that I have changed the return type of action method to IActionResult, as it contains both RedirectToAction() & View() result types.

Display Validation errors in ASP.NET Core

• Now it's time to display validation errors on the form itself, so now open your Registration.cshtml View file.
• Below each textbox, we need to add a <span> element, as shown in figure on right side.
• Inside this <span> element, I have use Validation Tag Helper named asp-validation-for and this Tag Helper is taking Username as a value.
• So, if there's any validation error appeared for Username, then it will be displayed here.
• Let's add this <span> element below all the textboxes, as shown in below figure:

• You can see in above figure, that I have placed <span> element containing asp-validation-for Tag Helper, below every input field.
• One more thing to note here is that I have added an option element Please Select, in both of my <select> tags, I have encircled them in above figure.
• Now let's run our application, and without entering any data, hit the Register button, and we will get validation errors, as shown in below figure:

• You can see in above figure that we are getting the Validation Error Messages for each component and at the end we have the summary of Validation errors.
• Moreover, for our Select boxes now we have a default option "Please Select", that's why we are getting Validation Errors for them as well, as now their value is null.
• If we select any option, then it will get value from the respective enum but in case of Please Select, its null-able and giving us Validation Error.
• We haven't added any Bootstrap design on these elements, as I want to keep things simple for now. ( We will design them later )

So, that was all for today. I hope you have enjoyed today's lecture. In next tutorial, we will have a look at detailed introduction to Entity Framework Core. Till then take care & have fun !!!

Create a Registration Form in ASP.NET Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at How to Create a Registration Form in ASP.NET Core. It's our 13th tutorial in ASP.NET Core series. In our previous lecture, we have seen How to use Tag Helpers in ASP.NET Core and have also discussed link, image & environment Tag Helpers. Today, we will have a look at Form Tag Helpers and with their help we will design a simple Registration Form in ASP.NET Core. It will be a quite lengthy tutorial so if you got into any trouble, then ask in comments. So, let's create our Registration Form:

Create a Registration Form in ASP.NET Core

• Let's create a new action method named Registration, in our Home Controller class, as shown in figure on right side.
• I have also returned a View, so let's create a new Razor View in Views > Home folder and give it a name Registration.cshtml.
• This View is going to execute, when someone will open up this link: http://localhost:61745/home/registration

• So, let's create our registration Form in this Registration View file, as shown in below figure:

• It's a bit lengthy code, so let's understand this code, part by part. I have also added the Engineers.cs Code in red box for better understanding.
• I have first used @model directive and included Engineers class in this View file, as I want this user provided data to be linked with the properties of Engineers class.
• Next, I have given the Title for the Page which will be rendered to the Layout View file.
• Finally, I have used the <form> tag to create my Registration Form and I have used two Tag Helpers to provide the Controller & action method.
• So, when we will submit this form, then it will be redirected to the same page and I have also provided post method, So, this form will make a POST request, as shown in below figure:

• Inside this form, I have created label & input and have provided a tag helper asp-for.
• asp-for tag helper will link this input with the respective property in Engineers class.
• As you can see, I have provided Username to my first asp-for tag helper and we also have a Username property in my engineers class.
• Moreover, this asp-for tag helper will generate the Name & Id fields of this <input> tag, which you can check by looking at the source code of your webpage.

• As you can see in HTML output, we have for attribute in <label> tag and in <input> tag, we have name & id attributes.
• I have created 3 Labels & Text Boxes for their respective properties in engineers data class, i.e:
  • Username.
  • Email.
  • FullName.

Enums in ASP.NET Core

• If you have studied C#, then you must be aware of C# Enums, so let's create two enums for our project.
• As our site is related to Engineering, so I want the registering users to provide their University & Department Names and for that I have created enums.
• We can place Emums anywhere in our project, so I have created a new folder in the root directory and named it TepEnums.
• Inside this folder, I have created two enums, named as:
  • DeptEnums.
  • UniEnums.
• Inside these Enums, I have added few data and I am going to provide this data to my select elements in registration form, these enums are shown in below figure:

Select Tag Helpers in ASP.NET Core

• I have created 3 Textboxes at the start and then created two select element for Department & University.
• In this <select> tag, I have used asp-items tag helper and then provided it our newly created enum DeptEnum.
• I did the same with University <select> tag, so overall we are getting 5 values from our end user.
• Finally, at the end of our code, we have a Register button.
• Moreover, I have also changed the data type of University & Department from string to their respective enum, shown in the first figure of this tutorial.

Import Namespaces in Layout Imports File

• We have to include the namespaces of our enums in the Imports Layout File, so that we could use them in all of our Views.
• Similarly, as we are linking for Registration form with engineers class, which is present in Models folder, so we also have to include this Models Namespace, as shown in below figure:

• We have made all the changes and now it's time to run our web application and if everything goes fine, then you will get similar results:

• So, we have created our registration form but if you click on this Register Button, then it won't do anything except refreshing the page.

Create Method for adding New User

• We have created the font-end View for this registration form and have also created its action Method in Controller, but we haven't yet created it's model's function.
• So, let's open the IEngineersRepository.cs file in Models Folder and create a method in it for Adding New Engineer, using data coming from registration form, as show in figure on right side.
• We have declared the method in interface, so we have to provide its implementation as well in the EngineersRepository class, which is implementing this interface.
• So, open your EngineersRepository.cs file and inside this file, I have provided the implementation of AddNewEngineer() function.
• This function takes engineer as an input, which we will send it from Controllers class and when it gets this new engineers data, then we need to increment the id property, which has to be set internally.
• After that, I am adding this engineer variable in my _EngineersData array and finally returning the newly created engineer variable.
• So, we have successfully added the Model method for our Registration form, and when it will get the data, it will simply save it in the EngineerData array. ( We will save data in database in our coming lectures )

POST action method in ASP.NET Core

• Now open your HomeController.cs file, whcih has the action method Registration.
• This action method was used to open the Registration View but what will happen, when we press the Register button.
• When we press the REgister button, then HTML form will make a POST request so, let's create two method with same name i.e. Registration.
• First method will handle the HTTP Get request i.e. will simply display the Registration Form.
• Second method will handle the HTTP POST request and will execute on Register Button press, as shown in below figure:

• You can see in above figure, I have placed an [HTTPGet] attribute before first action method and thus it will simply serve the respective View file.
• While, I have placed [HTTPPost] attribute before second method and thus when we press the Register Button, a POST request will be generated and thus this action method will execute.
• In this Post method, I have simply executed the AddNewEngineer method of Model class, which will add this new engineer.
• Finally, I have redirected it to Info Page and have shown the details of newly created user.
• Now when you run your project, and add users' data using registration form then it's info page will open up with new engineer's data.
• I haven't added any Bootstrap code yet, as I want to keep things simple, we will design our application in future lectures.

So, that was all for today. So far, we haven't placed any validation check on our submitted data, we will do that in our next lecture. Till then take care & have fun !!!

HTML Tag Helpers in ASP.NET Core

Hello friends, I hope you all are doing great. In today's lecture, we will have a look at HTML Tag Helpers in ASP.NET Core. It's our 12th tutorial in ASP.NET Core series. If you have worked on ASP.NET then you must have been familiar with HTML Helpers. Tag Helpers are quite similar to HTML Helpers with slightest difference in its syntax. Tag Helpers are new in ASP.NET Core and were not part of ASP.NET. So, let's first understand what are Tag Helpers & why we need to use them and at the end we will also discuss few common tag helpers in detail. So, let's get started with HTML Tag Helpers in ASP.NET Core:

HTML Tag Helpers in ASP.NET Core

• HTML Tag Helpers in ASP.NET Core are server side components and thus executed on the server to create HTML elements of the webpage.
• ASP.NET Core has a lot of built-in Tag Helpers for links, images, forms etc. available in Microsoft.AspNetCore.Mvc.TagHelpers assembly and we need to use @AddTagHelper directive to include them in Views.

• As we want to use these Tag Helpers in all of our Razor Views, so I am going to include this TagHelper assembly in _ViewImports.cshtml file, which we have created in 10th lecture and has all the assemblies importing statements.
• AS you can see in the figure on right side, I have imported Tag Helper assembly using @AddTagHelper directive and it has two parameters.
• I have added * in first parameter, which means I want to import all the Tag Helpers available in TagHelper assembly.

So, after adding this statement, we can now use Tag Helpers in our project. Let's have a look at few commonly used Tag Helpers:

HTML Tag Helpers for Hyperlinks

• In our Bootstrap lecture, we have added three <a> elements in our Info View file but haven't provided the href value.
• So, now let's use Tag Helpers to provide link value for href parameter of <a> tag, as shown in below figure:

• I have marked these 3 links with red box and you can see that I have used 3 link Tag Helpers i.e.
  • asp-controller: I have provided the controllers name i.e. home.
  • asp-action: I have provided the action method name i.e. Index for first link & Info for second.
  • asp-route-id: I have provided the third parameter in it, while id is the name of the parameter.
• All Tag Helpers start with asp- prefix and are embedded in HTML tags as simple parameters.
• Now let's run this app and open this Info link and have a look at the HTML source, as shown in the below figure:

• I have encircled the output links with green box and you can see that we don't have any tag helpers in our output file.
• Instead, these tag helpers generated the HTML code of href parameter and we can see that the first link is of Homepage and the second link is of /Home/Info/3.
• Now, you must be wondering that why we need to use Tag Helpers, as we can easily add the hard coded links.
• The main benefit is, in future if you change your Controllers' names then your links will be changed and if you have placed them hard coded then you have to manually change them one by one.
• But with Tag Helpers, there's no need to change as they will get the update name of Controller or action method and will provide the corrected link.
• Moreover, Tag Helpers are inline with HTML unlike HTML Helpers and are thus easy to use.

HTML Tag Helper for Images

• If we change any existing image on our server without changing its link, the browser will keep on showing the old image, because of Browser Cache.
• So, in order to avoid that we need to use a builtin HTML Tag Helper called asp-append-version in <img> tag, as shown in below figure:

• So, now if the image content is changed on the server then it will make the new image available to the end user.
• If you check the HTML code of your output page, then you will find a unique string appended to your image link, which is calculated using the image content.
• So, if image content is changed then this string will also be calculated again and thus browser will know that there's new content in the image and will load it again from the server, instead of providing it from its cache.

HTML Tag Helper for Environments

• Using Environment Tag Helper, we can execute different content of the webpage, based on application environment.
• We have studied Environment variable in 5th lecture and have seen that we set this variable in lauchSettings.json file.
• In our Development Environment, we need to use non-minified versions of all of our third part client side libraries i.e. Bootstrap, Jquery, Javascript etc.
• But in Staging or Production Environment, we should use minified versions and for better performance, we should get them from their CDN networks.
• So, let's make these changes using Tag Helpers, open your _Layout.cshtml file, placed in Views > Shared folder.
• We have linked Bootstrap file with our project here, so let's add some code in it, as shown in below figure:

• You can see in above figure that in green box, I have placed the link to non-minified version of Bootstrap inside Environment tag helper and I have included Development Environment.
• So, this link will be used only when we are working in Development Environment.
• In the red box, I have excluded Development Environment, so this block will work for all Environments except Development.
• Inside this block, I have placed the Bootstrap CDN link, which you can get from its official site.
• But what if, this external CDN is link is down for some reason, then your server won't be able to fetch those files and thus your site won't work perfectly.
• In such cases, we should fall back to our own server and get the minified version of Bootstrap.
• So, let's add few more Tag Helpers to achieve that, as shown in below figure:

• As you can see in above figure, I have added five tag helpers in <link> tag.
• So if our application is unable to get the CDN link, then it will fallback to our own server & get the minified version of Bootstrap.
• These tag helpers are injecting a JavaScript code to check, whether we got the CDN link or not.
• As we have added this code in our Razor Layout file so it will be applied to all of our Views. ( We will add more Views in coming lectures )

So, that was all for today. I hope you have enjoyed today's lecture. In next tutorial, we will have a look at How to design Bootstrap navigation Menu in ASP.NET Core. Till then take care & have fun !!!

How to include Bootstrap in ASP.NET Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at How to include & use Bootstrap in ASP.NET Core. It's our 12th tutorial in ASP.NET Core series. As it's ASP.NET Core tutorial so I am not going to explain bootstrap much. But you must have the basic idea of Bootstrap, its a client side package of CSS libraries, designed by twitter and these days you can't design a responsive site with Bootstrap as it follows symmetry and is too easy to use. So, let's get started with How to include Bootstrap in ASP.NET Core:

How to include Bootstrap in ASP.NET Core

• There are many third party tools ( Bower, NPM, WebPack etc. ) available in Visual Studio for installing client side applications like Bootstrap, JavaScript, Jquery etc.
• But we are going to use builtin tool of Visual Studio called LibMan ( short for Library Manager ), for installing third party packages, we can use both file system & CDN.

• LibMan is a light-weight client side library acquisition tool, which not only downloads the third party libraries but also keep a track in a special file.
• In order to open Library manager, right click on your project's name in Solution Explorer & then Add > Client Side Library and below dialog box will open up:

• You can see in above figure that I have made a search for twitter-bootstrap@4.3.1 in the Library Text Box and LibMan previewed its files.
• After that I have changed the Target Location and its now wwwroot/lib/bootstrap, so my bootstrap files will be placed inside lib folder of wwwroot folder.
• After these settings click the Install button and these bootstrap files will be installed.
• Let's also install jquery using Library manager, as shown in below figure:

• Library Manager has also created LibMan.json file which keeps the record of all the third party packages installation.
• I have placed both bootstrap & jquery in wwwroot > lib folder, as shown in below figure:

• That's how, we can easily install third party client side packages in ASP.NET Core.
• Now, we need to include this Bootstrap file in our Razor Layout View file, as shown in below figure:

• You can simply drag & drop the bootstrap file in this Layout file and the link tag will automatically be generated.
• So, now let's add some bootstrap code in our Info View file to make it look eye caching, as shown in below figure:

• Now run your application and navigate to info page and if everything goes fine then you will get similar results, as shown in below figure:

• Now you can see our page got a much nicer look with bootstrap included.

So, that was all about bootstrap in ASP.NET Core. I hope you have enjoyed today's lecture. In the next tutorial, we will have a look at Tag Helpers in ASP.NET Core. Till then take care & have fun !!!

URL Routing in ASP.NET Core

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at URL Routing in ASP.NET Core. It's our 11th tutorial in ASP.NET Core series and it's an important but quite easy concept to understand. You must be wondering how we are routing rite now as we haven't added any routing codes yet. But if you remember, we have used MVC with default route middleware in our pipeline and this middleware automatically sets up this default URL routing for our web application.  So, let's understand how this URL Routing works in ASP.NET Core:

URL Routing in ASP.NET Core

• URL Routing in ASP.NET Core is used to provide the controller's action method to the incoming HTTP request.
• In simple words, when a user enters an HTTP URL in its browser, then it is greeted by the respective controller's method and which controller's method should by executed, it is decided by the URL Routing.

• As you can see in below figure that our controller class has two action methods in it i.e. Index & info:

• By default, first segment of URL ( home in our case ) is the name of the Controller and the second segment is the name of the action method. So, when we have info in the second segment then Info action method will be executed.
• So, now let's understand this third segment in URL link, which is routed as a parameter to the action method.
• If you remember, when we created the Info action method then we have hard coded the value of Engineers to 1.
• So, let's make it flexible and ask the user to enter it as a third segment in the URL.
• Open your Controller's file and make these changes to Info action method, as shown in figure on right side.
• I have added a parameter int id in our Info method and then placed this id in the GetEngineers function.
• So, now run your function and navigate to /home/info/3 and now you will get the data of your third engineer, as shown in below figure:

• Now, we have automated our Info method by adding this third parameter and we can view any engineer's data quite easily.
• But, if you open /home/info/ without the third parameter, then you will get a run time error and one way to avoid it is by making this third parameter null-able, as shown in figure on right side.
• I have made the id null-able and then assigned it a default value of 1 by using id??1.
• So, now if you don't add the third parameter then it will show you the data of first engineer by default.
• This default routing of ASP.NET Core is also called Conventional Routing.

I hope you have understood the Conventional URL Routing in ASP.NET Core, so that was all for today. In the next lecture, we will have a look at How to include Bootstrap in ASP.NET Core. Till then take care & have fun !!!