How to implement Modal Dialog in Angular 2 and above

Your common child modal component will be as below

import {Component,Input, ViewChild} from '@angular/core';
import { ModalDirective } from 'ngx-bootstrap';

@Component({
  selector: 'common-modal',
  template: `
   <div bsModal #childModal="bs-modal" class="modal fade" tabindex="-1" role="dialog" aria-labelledby="mySmallModalLabel" aria-hidden="true">
  <div class="modal-dialog modal-sm">
    <div class="modal-content">
      <div class="modal-header">
        <h4 class="modal-title pull-left">{{title}}</h4>
        <button type="button" class="close pull-right" aria-label="Close" (click)="hideChildModal()">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <ng-content select=".modal-body"> </ng-content>
      </div>

      <div class="modal-footer">
        <div class="pull-left">
          <button class="btn btn-default" (click)="hide()"> Cancel </button>
        </div>
      </div>
    </div>
  </div>
</div>
  `,
})
export class CommonModalComponent {
   @ViewChild('childModal') public childModal:ModalDirective;
   @Input() title:string;
  constructor() {
  }
  show(){
    this.childModal.show();
  }
  hide(){
    this.childModal.hide();
  }
}

Using the child component in your parent component will look as below

import {Component, ViewChild, NgModule,ViewContainerRef} from '@angular/core'
import { BrowserModule } from '@angular/platform-browser';
import { ModalDirective,ModalModule } from 'ngx-bootstrap';
import {CommonModalComponent} from './child.modal';
@Component({
  selector: 'my-app',
  template: `
    <button type="button" class="btn btn-primary" (click)="childModal.show()">Open modal</button>
    <common-modal  #childModal [title]="'common modal'"> 
    <div class="modal-body">
    Hi heloo </div>
    </common-modal> 

  `,
})
export class AppComponent {
  @ViewChild('childModal') childModal :CommonModalComponent;
  constructor(private viewContainerRef: ViewContainerRef) {
  }

}

Using the above code you can have a separate common modal dialog which can be reused, so that your header & footer remains the same and you can use Content-Projection to use change the body of the modal dialog.

LIVE DEMO

The below answer is in reference to the latest ng-bootstrap

Component Controller

import { TemplateRef, ViewChild } from '@angular/core';
import { NgbModal } from '@ng-bootstrap/ng-bootstrap';

@Component({
  selector: 'app-app-registration',
  templateUrl: './app-registration.component.html',
  styleUrls: ['./app-registration.component.css']
})

export class AppRegistrationComponent implements OnInit {

  @ViewChild('editModal') editModal : TemplateRef<any>; // Note: TemplateRef

  constructor(private modalService: NgbModal) { }

  openModal(){
    this.modalService.open(this.editModal);
  }

}

Component HTML

<ng-template #editModal let-modal>

<div class="modal-header">
  <h4 class="modal-title" id="modal-basic-title">Edit Form</h4>
  <button type="button" class="close" aria-label="Close" (click)="modal.dismiss()">
    <span aria-hidden="true">&times;</span>
  </button>
</div>

<div class="modal-body">
  <!-- YOUR FORM DATA -->
</div>

<div class="modal-footer">
  <button type="button" class="btn btn-outline-dark" (click)="modal.close()">Save</button>
</div>

</ng-template>

app.module.ts

import {NgbModule} from '@ng-bootstrap/ng-bootstrap';

@NgModule({
  declarations: [
    ...
  ],
  imports: [
    ...

    NgbModule

  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }