.Net Interview Questions Asked in MNC.

  1. Can we create multiple dbcontext in single entity framework application, please explain if not then why and if yes then what will be real-time use of this.
  2. In code first approach how new tables updated to database through entity framework.
  3. What is odata in webapi and what is controller name for odata.
  4. How you can test your webapi through unit testing.
  5. if webapi and client application is hosted on different environment then what type of challenges you face.
  6. What is Cors in webapi.
  7. What is attribute routing .
  8. What are the attributes which is applied to class and methods in unit testing.
  9. Write a query to find record from table where name start with “S”.data should be fetch using entity framework.

      WebAPI questions:

  1. Have to experience in webapi and are you consumer or developer of those api’s ?
  2. What is difference between wcf and webapi. If wcf is hot in demand then why you select webapi ?
  3. What does REST means,how state transfer through the network?
  4. What are necessary steps to create Webapi from scratch?
  5. What is difference between conventional routing and attribute routing.Is both routing works together and when you select conventional routing and attribute routing?
  6. How to enable attribute routing?
  7. How many filters are in webapi ?
  8. How to register global filters in Webapi ?
  9. What is major security concern in webapi ?what is CORS and how to make webapi compatible to support CORS, define all necessary steps ?
  10. Have you implement security in webapi, if yes then what approach you have followed. Explain in detail.
  11. What is Oauth and Owin based authentication?
  12. How you serialize and deserialize json object to C# native objects?
  13. What is OWASP? What are the top 10 security flaws ?
  14. How you can test webapi ?

 

MVC interview Questions:

  1. What is routing in MVC and how MVC routing differs from WebApi Routing?
  2. What is Constraints in Mvc routing and how many ways to implement this?
  3. What is Child Action in Mvc ?
  4. What is advantage of Mvc as compare to conventional web form application?
  5. How you implement caching in Mvc ?
  6. How you handle XSS and CSRF in Mvc ?
  7. Have you used code first approach in Mvc if yes then how you manage data concurrency?
  8. In code first approach, when new property added to entity then what happen? Is new column added in database table or any error comes. If errors comes then what is the process to resolve this?
  9. Can we use multiple dB contexts with single database in code first approach?

SQL Interview questions:

  1. What is CTE and how CTE differ from temp tables?
  2. Is it possible to create index on views?
  3. What is table valued functions and variable and give me real-time scenario when you can use these?
  4. What is covering indexes?
  5. Can you apply joins with table value functions?
  6. What is left outer join?
  7. Have u create user defined data types in Sqlserver and explain with real-time example where you had used?
  8. How you can ensure store procedure cannot me read after creation?

 

Oops Interview Questions:

  1. How many design patterns you have used, related each one with real-time use case in your project?
  2. What is difference between Abstract class and interface?
  3. What is the importance of interface in unit testing?
  4. Which test framework you used in your last project? Have you ever used MOQ?

 

WebApi Exception: Multiple Action were found that match the request.

Usually webapi controller contains GET,GET(id),Post,Put,Patch & Delete methods but sometimes we need to create multiple get or post method or more custom methods to support http verbs.

Let say we have existing Get() method and now we want to add one more custom method names as “GetALL()” to support http Get verb.My Api Controller code looks like:

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When you defined your new method with http Get verb along with existing Get() method  and run webapi than below error comes:

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WebApiConfig.cs for above code which is created by default when new api project created.

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So talk about why this error comes if every thing is perfect in code.So look at the defined route in config file and .In webapi routing only controller name is mentioned in route template and there is no action like (Get,Post or any Custom Action Name) are defined.

Here is the difference in mvc routing and Webapi routing. In mvc routing action name are by default included in Url’s while in webapi actions names are not mandatory.

MVC Route: url: “{controller}/{action}/{id}”

WebApi Route: routeTemplate: “api/{controller}/{id}”

So when ever any request comes to webapi,it always goes to default http verbs and if default GET or Post methods used then it returns a response to the client.

But when we have defined some custom methods along with default Api methods than same request will thrown an exception because now there are multiple action methods that supports http verbs  and server not able to identify which method have to execute.

Why this happened because we have not defined any specific action name in webapi Route.

So what is the solution of this problem as we need many custom action names along with default http verbs in our webapi solution to solve the day-to-day business needs.So question comes in mind whether custom method names are allowed in webapi or not.

Then answer is “yes”,off-course we can add custom action names as much as we want but some changes have to make in webapi routing to support custom action names.

To support custom action method names we have to add {action} with controller name in default route as per below:

routeTemplate: “api/{controller}/{action}/{id}”

Now Complete Webapiconfig.cs after make some changes:

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Now Test our methods with these changes.

.1.when request goes to default methods:

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2.When request goes to custom action method (GetAll)

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WebApi Field Level Response Without Implementing Odata.

Download Complete Project: WebApiFieldLevelSelection

When you are writing a RESTful web API you often want to allow clients to feed a list of fields to the API that the clients need. The reason is to return only the useful data to the client. Say for example, you have an entity called Product that has many properties. The client may need only a few properties of the Product object. If you return the entire object every time the client asks for a product.

it unnecessarily wastes bandwidth and increases the response time. So to avoid that you can accept a list of fields the client wants and return only those. How can you do that?

Odata is best way to achieve this where you can use $Select command to fetch specific database fields in response.

Problem comes when webapi not implementing odata then how can achieve this functionality ?

To achieve this you have to use some basic .net objects like dynamic,expendoObject or  generic collections etc.

Let’s resolve the problem step by step:

  1. Create empty Webapi Project with controller name as “ProductCategory” with Two Get method.one is parameter less and other with string parameter that will accept comma separated field list in request.
  2. Get() method will return all fields of database in response while Get(string fields) method accept list of fields and return desired fields in response.
  3. In below example i have use hardcoded list with dummy values.You may replace it with actual database.

    ProductCategroyController.cs

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 DynamicObject Method:

DynamicObject accept the list of fields  and return object.here I have use .net reflection to get the value of each fields and respective value to dictionary<string,object> object. later this dictionary object pass to linq query.

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ApiHelper.cs

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OUTPUT:

  1.  When user pass two fields (productid and productName) as query string in request.you can see only two fields are coming in json response.

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  1.  When User pass three fields (productId,ProductName,Price) as query string in request.You can see now three fields are coming with json response.

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So you can see how you can implement field level selection on webapi without Odata implementation.

MVC View With Multiple Models Using Tuples And Expendo Object.

DownLoad Sample Project: MvcViewWithMultipleModels 

In mvc programming model a view can be associate with multiple models and developers have to send multiple models from controller to cshtml page.There are many  common approaches like ViewBag,ViewData,ViewModel etc can be use to achieve this functionality.

But here i am not going to demonstrate all above three approches.you can use .net framework 4.0 new features to pass the multiple models from controller to view effeciently.

  1. Expendo Object
  2. Tuples

1.) Using Expendo Object:

The ExpandoObject class enables you to add and delete members of its instances at run time and also to set and get values of these members. This class supports dynamic binding, which enables you to use standard syntax like sampleObject.sampleMember instead of more complex syntax like sampleObject.GetAttribute(“sampleMember”).

Let say you have two models named as “Department” and “Employee” and you want bind these two models with mvc view.Below are the model definitions:

Department.cs:

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Employee.cs

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Controller.cs :

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Method details fetch employee and department details as per below:

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View (Index.Html):

On the view you have to use dynamic property of .net framework 4.0 and need to be declared as @model dynamic.this is not strongly type of view.

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Rendered output:

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2.) Using Tuples:

In C#, tuples are used to store data. It’s sort of like a variable, but in order for it to be a tuple it must contain more than one value. Each instance of a tuple has a fixed number of items within it (and each item has its own distinct type, eg. a variable or an int), and once the tuple has been created, it can’t be altered in any way.

Let’s continue with previous create models and there are no changes in model class.the only change need to do in controller and view.

Now Controller looks like after code updating for tuples:

HomeController.cs

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View (index.html)

you have use tuples at top of the view and you have to declare as per below:

@model Tuples<List<Employee>,List<Department>

complete view looks like:

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Rendered Output:

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You can see there is no change in final rendered output.

this article describe how to pass multiple models from controller to view .I hope this will be helpful for programmers.

“Drop If Exists” Syntax in Sql-Server 2016

With the recent Sql server 2016 Service Pack 1, one important feature “Drop If Exists” syntax has been added, which developers were missing from long time.Prior to Sqlserver 2016 developers need to check database objects existence before creating.

Prior to sql server 2016,If Exist clause was used to check the db object existence then developers were taking appropriate action if objects exists.

If the Database objects doesn’t exists it will not raise any error, it will continue executing the next statement in the batch.

If Exist In Older Versions:

Previously you need to add an IF EXISTS() condition to check if the database object already exists or not. If exists then drop and then create a new objects, like:

IF EXISTS (SELECT name FROM master.sys.databases WHERE name = N'DatabaseName')
  Do your thing...

Example:
IF EXISTS (SELECT name FROM master.sys.databases WHERE name = N'Sql2016DB')
drop database Sql2016DB

New Way :

You can see new syntax much easier and shorter as compare to older syntax.Developer’s not need to memories whole long syntax to check and drop database objects.

Query Syntax: DROP <DbObject> [ IF EXISTS ] <ObjectName>

Here DbOject can be any database,store procedure,functions,Tables or triggers.


Let See  real-time examples for few important database objects:

1)Drop Database if Exists:

Now query syntax to drop the database is very easy and shorter.

Syntax:  Drop Database If Exists  <DatbaseName>

Example: let say our database  name is SqlDb2016 than below query will drop database by using new query syntax.

Drop database if exists SqlDb2016

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2. Drop Tables If Exists:

Syntax: Drop Database If Exists <TableName>

Examplelet “EmployeeMaster” is a table in Sqldb2016 database than below query will drop table if exists in database.

Old Syntax :

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New query Syntax in Sql Server 2016

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3.Drop Procedure If Exist:

Drop procedure query is very often to use during the complex procedure writing and developers needs to apply some logic to check whether procedure is exists in database or not.

New “Drop If Exists” query syntax make developers life easy and new syntax is more short and memorable.

Old Query Syntax:

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New Query Syntax:

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4.) Drop Function If Exists:

User-defined functions are routines that accept parameters, perform an action and return the result of that action as a value. The return value can either be a single scalar value or a result set (table).

Old Query Syntax:

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New Query Syntax:

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5.) Drop Views If Exists:

A view is a virtual table based on the result-set of an SQL statement.A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.

Old Query Syntax:

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New Query Syntax:

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6.)Drop Trigger If Exists:

A trigger is a special kind of stored procedure that automatically executes when an event occurs in the database server. DML triggers execute when a user tries to modify data through a data manipulation language (DML) event. DML events are INSERT, UPDATE, or DELETE statements on a table or view. These triggers fire when any valid event is fired, regardless of whether or not any table rows are affected.

Old Query Syntax:

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New Query Syntax:

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Drop if Exists statement is not limited to above mentioned database objects it can be use with other database objects like :

  • Index
  • constraints
  • Columns
  • Schema
  • Synonym
  • Type
  • Users
  • Role

 

SqlServer 2016 Virtual Machine Setup In Microsoft Azure.

Azure VMs provide a way to move your on-premises SQL Server workloads and applications to the Cloud.

There are many reasons that you might choose to host your data in Azure. If your application is moving to Azure, it improves performance to also move the data. But there are other benefits. You automatically have access to multiple data centers for a global presence and disaster recovery. The data is also highly secured and durable.

Find step-by-step guidance for this process in the tutorial, Provision a SQL Server virtual machine in the Azure portal.

1.Login on azure portal by using your  Microsoft azure account. if you not have any azure account then you may use Microsoft azure trial.

 

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2. look for virtual machines option from the left blade and and click on it.Now click “Add” option and select sqlserver virtual machine from all available images.A2.PNG

Now All available images will come in new pane and you have select sqlserver 2016 image.

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3. Under Select a deployment model, verify that Resource Manager is selected. Resource Manager is the recommended deployment model for new virtual machines. Click Create.

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Configure Virtual Machine

There are five important steps to configure the virtual machine as per below:

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1.Configure Basic Settings:

Provide following information on basic configure tab:

  • Provide Unique Virtual Machine Name.
  • User name for the local administrator account on the VM.
  • Provide a strong Password.
  • Select Subscription what ever you have.
  • In the Resource group box, type a name for a new resource group. Alternatively, to use an existing resource group click Select existing.To know more about resource group.https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-group-overview
  • Select a Location for this deployment.
  • Click OK to save the settings.

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2. Select Virtual Image Size:

There are lot of virtual images size available on azure portal. Initially most recommended images comes on screen and you can  select any other image size which is most appropriate for you.

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3.Configure optional features:

On the Settings blade, configure Azure storage, networking, and monitoring for the virtual machine.A8.PNG

4.Configure sql server settings:

Sql server configurations is important section of virtual machine setup,here you have to configure various type of settings like Authentication,Network connectivity.

  • Public (internet) to allow connections to SQL Server from machines or services on the internet. With this option selected, Azure automatically configures the firewall and the network security group to allow traffic on port 1433.
  • Local (inside VM only) to allow connections to SQL Server only from within the VM.
  • Private (within Virtual Network) to allow connections to SQL Server from machines or services in the same virtual network.
  • If you require SQL Server Authentication, click Enable under SQL authentication.Under Sql authentication you have to specify username and password.

Here i am going with public network with Sql authentication.

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5. Summary:

this is last step of virtual machine configuration and here you only have to review all the steps activity from step 1 to step 4.If all the things are good then click ok. Now your Sql Server machine setup is complete and ready to use.

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Click again on virtual machine option in left blade of screen and now you can see your newly created sql server machine is listed.

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Connect virtual machine with Remote Desktop

Use below steps to connect VM with remote desktop:

  • Click on your new SQL virtual machine. A Virtual machine blade displays your virtual machine details.
  • At the top of the Virtual machine blade, click Connect.
  • The browser downloads an RDP file for the VM. Open the RDP file.

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Once you have opened .RDP file,you have to enter your username and password. These are the same username and password which was specified in Sql authentication.

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Once you have entered correct username and password then you will navigate to your virtual machine.

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After you connect to the SQL Server virtual machine, you can launch SQL Server Management Studio and connect with Windows Authentication using your local administrator credentials. If you enabled SQL Server Authentication, you can also connect with SQL Authentication using the SQL login and password you configured during provisioning.

 

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What is TypeScript and why would we use it in place of JavaScript?

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It’s never been a better time to be a JavaScript developer! JavaScript is everywhere now – it’s on the front and back-end of a website, and many desktop text editors are powered by JavaScript. In fact you can build a whole range of desktop applications using web technologies as their foundation.

TypeScript is a Superset of JavaScript.

TypeScript: Making .NET Developers Comfortable with JavaScript

“.TS” is TypeScript File Extension as similar to java script file extension “.Js”.

TypeScript is a free and open-source programming language developed and maintained by Microsoft. It is a strict superset of JavaScript, and adds optional static typing and class-based object-oriented programming to the language.TypeScript may be used to develop JavaScript applications for client-side or server-side (Node.js) execution.

TypeScript is designed for development of large applications and transcompiles to JavaScript.[7] As TypeScript is a superset of JavaScript, any existing JavaScript programs are also valid TypeScript programs.

TypeScript adds common concepts such as classes, modules, interfaces, generics and (optional) static typing to JavaScript. All JavaScript code is valid TypeScript code so it can be added seamlessly to any project. The TypeScript compiler emits JavaScript.

Installing TypeScript

There are two main ways to get the TypeScript tools:

  • Via npm (the Node.js package manager)
  • By installing TypeScript’s Visual Studio plugins

Visual Studio 2015 and Visual Studio 2013 Update 2 include TypeScript by default.

For NPM users:

Open Command prompt and execute below command.It will take some time to download and install all required assemblies.

npm install -g typescript

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Now Validate the setup process by executing Tsc command on same command prompt.

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Supportive tools for TypeScript:

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Benefits of typescript:

  • Due to the static typing, code written in TypeScript is more predictable, and is generally easier to debug.
  • Makes it easier to organize the code base for very large and complicated apps thanks to modules, namespace and strong OOP support.
  • TypeScript has a compilation step to JavaScript that catches all kinds of errors before they reach runtime and break something.
  • The upcoming Angular 2 framework is written in TypeScript and it’s recommended that developers use the language in their projects as well.

For more details please refer https://www.typescriptlang.org/docs/tutorial.html

TypeScript PlayGround:

Type Script Playground is online tool for developing and testing typescript programs without installing any external tools.It automatically translate type script to java script.

https://www.typescriptlang.org/play/index.html

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Some important features of TypeScript:

  1. TypeScript Code is Converted into Plain JavaScript Code
  2. Data Types
  3. Classes
  4. Access Modifiers and Properties
  5. Static and Instance Members
  6. Function Overloading
  7. Constructors
  8. Inheritance
  9. Interfaces
  10. Modules
  11. Type Annotation
  12. Generics
  13. Type inference
  14. Tuple
  15. Await

Since TypeScript generates plain JavaScript code you can use it with any browser. Overall TypeScript is a promising language  that can certainly help you neatly write and organize your JavaScript code base making it more maintainable and extensible.