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C#,.NET and Azure insights for developers

ashish

Create a WebApp in Azure

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Azure Web Apps
Azure App Service is used for creating HTTP-based service and could be used for hosting web applications, REST APIs, and mobile back ends.It comes in the is a platform-as-a-service or PaaS deployment model.
It supports the following languages:

  • ASP.NET
  • ASP.NET Core
  • Java
  • Ruby
  • Node.js
  • PHP
  • Python

There are numerous options for hosting web applications in Azure but Web Apps is best option in most cases.You can create web application in azure using the Web Apps in App Service by using either of the following:

  • Portal
  • Powershell
  • CLI

Portal

If you want to create Web App using the portal then you can use the following steps:
1.Select the Web category in the portal

azure portal web app

2.Select the Web App

3.Provide required details such as:

  • WebApp name this should be gloablly unique as it uses the domain .azurewebsites.net
  • Publish method docker or code
  • Stack such as .NET or Java
  • OS Windows or Linux
  • Region Where you want to host your app service
  • App Service Plan Dev/Production or Isolated

CLI

1.Before creating the App service you need to create app service plan.You can create it using the az appservice plan create command

az appservice plan create --name NameOfAppServicePlan --resource-group NameOfResourceGroup --sku FREE

2.Create web app in the newly created App Service plan.

az webapp create --resource-group NameOfResourceGroup --plan NameOfAppServicePlan --name NameOfApp

3.If you want to connect to database then you need to configure it in the Startup classes ConfigureServices method:

services.AddDbContext<DatabaseContext>(options =>options.UseSql("Data Source=localdatabase.db"));

 

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Find repeated characters in a string in C#

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If you have a given string and you want to count the number of characters which are repeated in the string then you can use the following program.

public static void Main(string[] args)
{
int numberOfRepeatedChars=0;
char[] chars=new char[25];
string str="AAABCDEE";
char tocheck=(char)'a';
foreach(var i in str)
{
int charNo=0;
var asc=(char)i;
charNo++;
if(!chars.Contains((asc)))
{

chars[charNo]=asc;

}
else
{

numberOfRepeatedChars++;
}

}

Console.WriteLine(numberOfRepeatedChars);
}

the above program will print 2 as there are two characters which are repeated in the string which are A and E.

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Filed Under: C#

Inject Service into Component in Angular

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Angular framework provides dependency injection to automatically inject services. Whenever we specify a service as a constructor parameter ,Angular automatically injects the service instance in the class.You provide required services to the different components using constructor parameters.

In Angular a service is a class decorated with the @Injectable decorator:

import { Injectable } from '@angular/core';
@Injectable()
export class MockService {
constructor() { 
}
}

You can consume the declared service in your component as:

import { mock-service} from 'app/services/mock-service.service';
@NgModule({
declarations: [AppComponent]
imports: [BrowserModule],
providers: [MockService],
bootstrap: [AppComponent]
})

Though theoretically  you can use any logic in you service ,it is common to implement data access logic in service. Then you can inject service in your constructor class as:-

constructor (private http: HttpClient) {}
getStudents() : Observable<Student[]> {

return this.http.get(this.studentsUrl )
.map((res:Response) => res.json())
.catch((error:any) => Observable.throw(error.json().error || 'Server error'));
}

 

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Bootstrapping in Angular application

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Angular application is initialised or bootstrapped based on the configuration and the specified properties.The important parts of Angular application from bootstrapping point of view are:

  1. main.ts  This file defines the starting point of the angular application.It is defined by the following line in main.ts:
platformBrowserDynamic().bootstrapModule(AppModule);

We need to understand how this works.Angular initializes / bootstraps our application when the bootstrapModule() method is called.We pass the name of the root module to this method.So if our module is called AppModule then we call it as:

platformBrowserDynamic().bootstrapModule(AppModule)

bootstrapModule is in the @angular/platform-browser-dynamic.In the above line AppModule is the name of our root Module which we want to bootstrap.The platformBrowserDynamic object specifies that we want to execute the application in a browser.Please note Angular applications can execute on different types of platforms and not just on browser.

     2. app.module  Next important part for BootStrapping is the root Module which we passed to the bootstrapModule() method in step 1.The bootstrap property in the AppModule decorator specifies the component which we want to use for launching the application.Now Angular tries to find the selector specified of the roor component in DOM and initializes the component.Here the root component is declared as AppComponent.

We specify the bootstrap property in NgModule as:

@NgModule({
bootstrap: [AppComponent]
})

    3. RootComponent this is the actual component which defines the selector which is used for initializing the application.Our component is declared as:

@Component({
selector: 'app-root',

templateUrl: "./app.component.html",
...
})

export class AppComponent
{
}

      4.index.html This file actually declares the selector of the root component which we have declared above.

This relation can be depicted with the following image

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Select multiple columns in a LINQ query

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LINQ is useful for querying as we can query different various data sources such as XML documents,SQL databases, CSV Files, JSON documents etc. , using C# or any other .NET language.

LINQ provides two different ways to write queries:

  • Declarative query syntax which is SQL like syntax.It’s important to understand that the declarative syntax is also converted to extension method syntax at compile time.
  • Query operators  which are defined as extension methods in the System.Linq namespace. Examples of these are Where,Select and OrderBy.

We can select values from a data source such as a c# list using Select operation in LINQ.Select operation also allows us to select multiple columns in a Linq query.

Select multiple columns in a LINQ query

Selecting List items using  LINQ where clause

Suppose we have a List of items and we want to search for some values in the list. We can easily do that using the LINQ select operator.
For example, if we have a list of Employee classes declared as:


 var employeesLst = new List<Employee> { new Employee { Name = "emp1", Id = "1",Dept="Accounts" },
 new Employee { Name = "emp2", Id = "2",Dept="Finance" },
 new Employee { Name = "emp3", Id = "3",Dept="Finance" },
};

then we can filter the employees based on the Id, using the declarative syntax as:


 var selectedLst=from item in employeesLst
 where item.Id=2
 select item.Name;

The equivalent method chaining syntax , using LINQ extension methods is:

employeesLst.Where(item=>item.Id=2).Select(item=>item.Name);

But if now we want to select multiple Dept and Name fields then we can not use this since this will be invalid syntax in LINQ:


var selectedLst=from item in employeesLst
select item.Id,item.Name;

Remember Select is a projection operation.Projection operations are used to transform an object into a new object containing properties which are required.

Select multiple columns in a LINQ query

Since in this scenario we require properties which are not contained by any existing object, we can use the anonymous type using the following syntax:


 var selectedLst=from item in employeesLst
 where item.Id=2
 select new { item.Id, item.Name };

Anonymous type is used to define a type that contains just read-only properties, using object initializer syntax. It is a convenient way to define a type you don’t need to reuse in multiple places. Since we don’t need to use the properties defined by the anonymous type outside our LINQ query, so we use the anonymous type here. But anonymous type can not contain any other type of members such as methods or constructors.

Select multiple columns using extension methods and lambdas

We can write the above query using extension methods and lambdas as:


 employeesLst.Where(x.Id > 5)
 .Select(x=>new {
  item.Id, item.Name
  });

To order the values by a specific column you can use the OrderBy method and pass the column you want to order upon as a lambda:

employeesLst.Where(x.Id >5)
.Select(x=>new {
  item.Id, item.Name
  }).OrderBy(x => x.Id);

If you want to convert the returned values to a list you can use the ToList method:

mployeesLst.Where(x.Id >5)
.Select(x=>new {
item.Id, item.Name
}).OrderBy(x => x.Id).ToList();
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