If you are using .net web api and again and again you build your's project and run that you will see that your's runs on different port after running you will be get following error in console window

Error: No ‘Access-Control-Allow-Origin’ Header is Present – Origin ‘localhost:…’ is therefore not allowed access.

this is very comman issue which can stuck  the developer in web api 

you can remove this by just configure the Global.asax file in Application_BeginRequest section  

by the following code in which we just configure the header section of the service

protected void Application_BeginRequest(object sender, EventArgs e){

HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin","*"")

}

How to dynamically add and remove the validators from angular reactive forms?

For the Angular Developer most of the computer and learner want to know how to dynamically add and remove the validation in reactive Forms:

So the Angular provide the 3 set of the methods which can be used for this.

1. setValidators()
2. clearValidators()
3. updateValueAndValidity()

setValidators: setting the validation on the control on which you want to apply on this

clearValidators: If user want to remove the existing validations from the control then he

can use this method.

updateValueAndValidity: this method is always use when you set or clear the validation in

angular reactive forms.

for applying all the above method first we find the control in our typescript file by

following way

suppose on my component here is the HTML part of the phone control

<label class="radio-inline">

<input type="radio" value="phone" (click)="onContactPreferenceChange('phone')" formControlName="contactPreference" >Phone

</label>

Now on the ts file we will find the phone control by following way

const phoneControl = this.employeeForm.get('phone');

after this according to our need we can add or clear the validation from the control.

How to find out how many data are in the colums are in the upper case in sql server

In Most of the interview, Interviewer asked write down a query to find out the how many rows have upper case data.

so here is the answer to crack this question in the interview.

select * from T(table_name)
  where fld(coloum_name) = upper(fld) collate SQL_Latin1_General_CP1_CS_AS

You can force to check the case sensitive collation.

what is best way to deal with set a value in ReactiveForm?

Most of the angular developer say the which is the best way to set a value of reactive form
1. setvalue() or patchValue()

In my opinion patchValue() is the best way to initialize the reactive form because if accidently developer miss to assign a value of field in reactive form user get the error with dealing with setValue() method.
on the other hand if we deal with patchValue() user can not get any type of error if he accidently miss to assign any fileld in the form.

Problem: Must supply a value for form control with name 'say xyz'

Most of the angular developer face the above problem when they are dealing with Reactive forms

"Must supply a value for form control with name /......"

this is because we donot provide the all field value that are in the reactive form and we are using the setValue method in angular.

this problem can be solved by two ways.
1. you can provide the value of all form control that you are using with reactive form.
2. or in your's case you want to provide the value for the some set of formcontrol then instead of using setValue() we can use patchValue() for loading the data

Problem: Can't bind to 'formGroup' since it isn't a known property of 'form'.

Can't bind to 'formGroup' since it isn't a known property of 'form'.


Most comman problem in angular is : 'Can't bind to 'formGroup' since it isn't a known property of 'form'.'

this is because formGroup and formControl directive are provided by angular reactiveform

and probably you did not include this is your's angular app. so first you include this in your's angular app so that this error is gone

so include the reactive form directive in your's app.component.module by following way

import { ReactiveFormsModule } from "@angular/forms";

and also include this in imports array so your's

app.module.ts would we look like this

import { BrowserModule } from '@angular/platform-browser';

import { NgModule } from '@angular/core';

import { ReactiveFormsModule } from "@angular/forms";

import { AppRoutingModule } from './app-routing.module';

import { AppComponent } from './app.component';

import { CreateEmployeeComponent } from './employee/create-employee.component';

import { ListEmployeesComponent } from './employee/list-employees.component';

@NgModule({

declarations: [

AppComponent,

CreateEmployeeComponent,

ListEmployeesComponent

],

imports: [

BrowserModule,

AppRoutingModule

],

providers: [],

bootstrap: [AppComponent]

})

export class AppModule { }

and also include the FormGroup and FormControl in your's component.ts
in my case it is create-employee.component.ts
have a look

import { Component, OnInit } from '@angular/core';

import { FormGroup, FormControl } from "@angular/forms";

@Component({

selector: 'app-create-employee',

templateUrl: './create-employee.component.html',

styleUrls: ['./create-employee.component.css']

})

export class CreateEmployeeComponent implements OnInit {

employeeForm: FormGroup;

constructor() { }

ngOnInit() {

this.employeeForm = new FormGroup({

fullName: new FormControl(),

email: new FormControl()

})

}

onSubmit(): void {

console.log(this.employeeForm.value);

}

}

Now i can hope that your's error should be gone. enjoy......

can we use cookie concept in angular

Yes we can use the cookies in angular also angular cookies is much similiar as Angular 1.x but in angular 2,4 and 6 there is one extraa method is DeleteAll.
Angular uses the following method for cookie

1.      Check – This method is used to check the cookie existing or not.

2.      Get - This method returns the value of given cookie name.

3.      GetAll - This method returns a value object with all the cookies

4.      Set – This method is used to set the cookies with a name.

5.      Delete – This method used to delete the cookie with the given name

6.      deleteAll – This method is used to delete all the cookies

7.      and so on