ASP.NET MVC Interview Questions And Answers Part-3
Dependency Injection (DI) in ASP.NET MVC
Dependency Injection is a design pattern used to implement IoC (Inversion of Control) in software applications. In ASP.NET MVC, DI is used to inject dependencies into a class, rather than the class creating the dependencies itself. This makes the application more modular, testable, and easier to maintain. DI is often achieved using an IoC container.
Security and Filters in ASP.NET MVC
ASP.NET MVC provides various mechanisms for implementing security in web applications, including authentication and authorization. Filters in ASP.NET MVC allow you to implement cross-cutting concerns such as logging, caching, and security. You can use filters to enforce authentication and authorization rules, ensuring that only authenticated and authorized users can access certain parts of your application.
Unit Testing in ASP.NET MVC
Unit testing in ASP.NET MVC involves testing individual units of code (such as controllers, models, and views) in isolation to ensure they behave as expected. Unit tests help to verify that each unit of code works correctly, which can improve the overall quality of your application and make it easier to identify and fix bugs.
IoC or DI container
An IoC (Inversion of Control) container is a software framework that manages the dependencies between classes in an application. It is often used in conjunction with DI (Dependency Injection) to automatically resolve and inject dependencies into classes. IoC containers help to simplify the configuration and management of dependencies, making the application more flexible and easier to maintain.
Dependency Inversion Principle (DIP) and IoC
The Dependency Inversion Principle (DIP) is a design principle that states that high-level modules should not depend on low-level modules. Instead, both should depend on abstractions. IoC (Inversion of Control) is a design pattern that helps to implement DIP by allowing the flow of control to be inverted, so that the high-level modules define the interfaces and the low-level modules implement them.
Donut caching and Donut hole caching in ASP.NET MVC
Donut caching and Donut hole caching are caching techniques used in ASP.NET MVC to improve the performance of web applications. Donut caching allows you to cache entire pages, while Donut hole caching allows you to cache parts of a page. This can help to reduce the load on the server and improve the responsiveness of your application.
Authentication and Authorization
Authentication is the process of verifying the identity of a user, typically by asking for a username and password. Authorization is the process of determining whether a user has permission to access a resource or perform a certain action. In ASP.NET MVC, you can use authentication filters and authorization filters to enforce authentication and authorization rules, respectively, in your application.
Q1. What are ASP.NET MVC Filters and Attributes?
ASP.NET MVC Filters and Attributes: In ASP.NET MVC, filters are attributes that can be applied to controller actions to perform logic before or after the action is executed. They can be used to handle cross-cutting concerns such as logging, caching, authentication, and authorization.
Q2. What are different types of Filters in ASP.NET MVC?
Different Types of Filters in ASP.NET MVC: There are several types of filters in ASP.NET MVC:
Authorization filters: These are used to check if the user is authorized to access the action or controller.
Action filters: These are executed before and after the action method is executed.
Result filters: These are executed before and after the action result is executed.
Exception filters: These are executed when there is an unhandled exception thrown during the execution of the action method.
Q3. When Exception filters are executed in ASP.NET MVC?
Execution of Exception Filters in ASP.NET MVC: Exception filters are executed when there is an unhandled exception thrown during the execution of the action method.
Q4. What is the order of execution of filters in ASP.NET MVC?
Order of Execution of Filters in ASP.NET MVC: Filters in ASP.NET MVC are executed in the following order:
Authorization filters
Action filters
Response filters (Result filters)
Exception filters
Q5. How to configure filters in ASP.NET MVC?
Configuring Filters in ASP.NET MVC: Filters can be configured globally for all controllers or applied to specific controllers or actions using attributes. Global filters can be registered in the `Global.asax.cs` file.
Q6. How do Authentication and Authorization work in ASP.NET MVC?
Authentication and Authorization in ASP.NET MVC: Authentication is the process of verifying the identity of a user, while authorization is the process of determining if a user has permission to perform a certain action. In ASP.NET MVC, authentication and authorization can be implemented using different mechanisms, such as Forms Authentication, Windows Authentication, or OAuth.
Q7. How Forms Authentication and Authorization work in ASP.NET MVC?
Forms Authentication and Authorization in ASP.NET MVC: Forms Authentication in ASP.NET MVC allows you to authenticate users using a login form and store user credentials in an encrypted cookie. Authorization can be implemented using the `[Authorize]` attribute, which restricts access to controllers or actions to authenticated users only.
Q8. How to implement custom Forms Authentication and Authorization in MVC?
Implementing Custom Forms Authentication and Authorization in MVC: To implement custom forms authentication and authorization in ASP.NET MVC, you can create custom authentication and authorization filters by implementing the `IAuthorizationFilter` interface. You can then apply these filters to controllers or actions where custom authentication and authorization are required.
Q9. How to allow HTML tags in ASP.NET MVC?
Allowing HTML Tags in ASP.NET MVC: To allow HTML tags in ASP.NET MVC, you can use the “AllowHtml” attribute on model properties that should allow HTML input. This attribute tells the model binder to allow HTML content for that property.
Q10. What is caching and when to use it?
Caching and When to Use It: Caching is the process of storing data in a temporary storage area (cache) to reduce the time it takes to access the data. Caching can be used to improve the performance of an application by reducing the number of database queries or expensive computations. It is typically used for data that is expensive to retrieve or doesn't change frequently.
Q11. What are the advantages of caching?
Advantages of Caching: Some advantages of caching include:
Improved performance: Caching can reduce the time it takes to access data, resulting in faster response times for users.
Reduced server load: By caching data, you can reduce the number of requests that need to be processed by the server, leading to lower server load.
Better scalability: Caching can help improve the scalability of an application by reducing the resources needed to handle requests.
Q12. What is output caching?
Output Caching: Output caching in ASP.NET MVC allows you to cache the output of a controller action or a partial view. This can improve the performance of your application by caching the generated HTML and serving it directly from the cache instead of regenerating it for each request.
Q13. What is Donut caching and Donut hole caching in ASP.NET MVC?
Donut Caching and Donut Hole Caching in ASP.NET MVC: Donut caching and donut hole caching are techniques used to cache parts of a page while allowing other parts to remain dynamic. Donut caching caches the entire page except for specific sections (the "hole"), which are rendered dynamically. Donut hole caching caches the specific sections that need to be cached, while the rest of the page is rendered normally.
Dependency Injection
Q1. What is loose coupling and how is it possible?
Loose Coupling and How It's Possible: Loose coupling is a design principle that aims to reduce the dependencies between components of a system. It is possible through the use of interfaces, abstract classes, and design patterns such as Dependency Injection. By defining contracts (interfaces or abstract classes) for interactions between components, you can decouple the implementation details, allowing components to be easily replaced or modified without affecting other parts of the system.
Q2. What are the Dependency Inversion Principle (DIP) and IoC?
Dependency Inversion Principle (DIP) and IoC: The Dependency Inversion Principle (DIP) is a design principle that states that high-level modules should not depend on low-level modules. Both should depend on abstractions. IoC (Inversion of Control) is a design principle related to DIP, where the control of object creation and flow is inverted from the calling class to an external framework or container.
Q3. What is Dependency Injection (DI)?
Dependency Injection (DI): Dependency Injection is a design pattern used to implement IoC. It involves injecting the dependencies of a class from the outside rather than creating them within the class. This allows for better decoupling of components and easier testing.
Q4. What is Service Locator?
Service Locator: Service Locator is a design pattern where a central registry, known as the service locator, is used to locate and instantiate services or components. While it can be useful, it can also lead to tight coupling and make code harder to test and maintain compared to Dependency Injection.
Q5. What are different ways to implement Dependency Injection (DI)?
Different Ways to Implement Dependency Injection (DI):
Constructor Injection: Dependencies are passed to a class through its constructor.
Property Injection: Dependencies are set through public properties of a class.
Method Injection: Dependencies are passed to specific methods when needed.
Q6. What are the advantages of Dependency Injection (DI)?
Advantages of Dependency Injection (DI):
Improved testability: DI makes it easier to mock dependencies in unit tests.
Reduced coupling: Components become more modular and can be easily replaced or upgraded.
Better code reusability: Dependencies can be reused in multiple classes without duplication.
Q7. What is IoC or DI container?
IoC or DI Container: IoC/DI containers are tools that help manage the dependencies of an application. They automatically resolve dependencies and inject them into classes when needed. They help in reducing boilerplate code related to manual dependency injection.
Q8. What are popular DI containers?
Popular DI Containers: Autofac, Unity, Ninject, StructureMap, Simple Injector
Q9. What is Test Driven Development (TDD)?
Test Driven Development (TDD): Test Driven Development is a software development approach where tests are written before the actual code. The development cycle typically involves writing a failing test, writing the minimum code required to pass the test, and then refactoring the code to improve its design while keeping the tests passing.
Q10. What are the commonly used tool for Unit Testing in ASP.NET MVC?
Commonly Used Tools for Unit Testing in ASP.NET MVC:NUnit, MSTest, xUnit.net,Moq (for mocking dependencies)
ASP.NET MVC Interview Questions And Answers Part-4
ASP.NET MVC Interview Questions And Answers Part-2
ASP.NET MVC Interview Questions And Answers Part-1