Spring Angular CRUD Application

In this section, we are going to develop a CRUD (create-read-update-delete) web application. This application contains the student form that includes the CRUD features like add, view, delete, and update student. In this integration, we are using Spring Boot to handle the backend part and Angular to handle the frontend part.

Working of Application

Once we deployed our application on the server, a student form generates at the web browser.
The form facilitates to add and view students.
On clicking add student link, the page redirects to create student form where we can add a student by filling the required details and submit them.
Using view student link, we can fetch the details of the existing student. Here, each student also contains update and delete link.
So, we can update the details of the student and also delete them from the database.
Once completed, provide the URL http://localhost:4200/ at the web browser.

Tools to be used

Use any IDE to develop the Spring and Hibernate project. It may be STS/Eclipse/Netbeans. Here, we are using STS (Spring Tool Suite).
MySQL for the database.
Use any IDE to develop the Angular project. It may be Visual Studio Code/Sublime. Here, we are using Visual Studio Code.
Server: Apache Tomcat/JBoss/Glassfish/Weblogic/Websphere.

Technologies we used

Here, we are using the following technologies:

SpringBoot 2
Hibernate 5
Angular 6
MYSQL

Create Database

Let's create a database indigo. There is no need to create a table as Hibernate automatically created it.

Spring Module

Let's see the directory structure of Spring Boot we need to follow:

To develop a CRUD application, follow the below steps: -

Add dependencies to pom.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.4.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.main</groupId>
	<artifactId>Student</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>Student</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
	
		<dependency>
		    <groupId>org.springframework.boot</groupId>
		    <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
		</dependency>
	
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

Create the configuration class
Instead of XML, we perform annotation-based configuration. So, we create a class Config.java and specify the required configuration in it. However, there is one more configuration class StudentApplication.java. This class is provided by Spring Boot automatically.q

Config.java

package config;

import java.util.Properties;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScans;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.view.InternalResourceViewResolver;


@Configuration
@EnableTransactionManagement
@EnableAutoConfiguration(exclude = { HibernateJpaAutoConfiguration.class})
@ComponentScans(value = { @ComponentScan("boot.entry"),
	      @ComponentScan("Model"),
	      @ComponentScan("Controller"),
	      @ComponentScan("DAO"),
	      @ComponentScan("Miscallaneous"),
	      @ComponentScan("Service")})
public class Config {

	 @Value("${db.driver}")
	    private String DB_DRIVER;

	    @Value("${db.password}")
	    private String DB_PASSWORD;

	    @Value("${db.url}")
	    private String DB_URL;

	    @Value("${db.username}")
	    private String DB_USERNAME;

	    @Value("${hibernate.dialect}")
	    private String HIBERNATE_DIALECT;

	    @Value("${hibernate.show_sql}")
	    private String HIBERNATE_SHOW_SQL;

	    @Value("${hibernate.hbm2ddl.auto}")
	    private String HIBERNATE_HBM2DDL_AUTO;

	    @Value("${entitymanager.packagesToScan}")
	    private String ENTITYMANAGER_PACKAGES_TO_SCAN;

	    @Bean
	    public LocalSessionFactoryBean sessionFactory() {
	        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
	        sessionFactory.setDataSource(dataSource());
	        sessionFactory.setPackagesToScan(ENTITYMANAGER_PACKAGES_TO_SCAN);
	        Properties hibernateProperties = new Properties();
	        hibernateProperties.put("hibernate.dialect", HIBERNATE_DIALECT);
	        hibernateProperties.put("hibernate.show_sql", HIBERNATE_SHOW_SQL);
	        hibernateProperties.put("hibernate.hbm2ddl.auto", HIBERNATE_HBM2DDL_AUTO);
	        sessionFactory.setHibernateProperties(hibernateProperties);
	        return sessionFactory;
	    }

	    @Bean
	    public DataSource dataSource() {
	        DriverManagerDataSource dataSource = new DriverManagerDataSource();
	        dataSource.setDriverClassName(DB_DRIVER);
	        dataSource.setUrl(DB_URL);
	        dataSource.setUsername(DB_USERNAME);
	        dataSource.setPassword(DB_PASSWORD);
	        return dataSource;
	    }

	    @Bean
	    public HibernateTransactionManager transactionManager() {
	        HibernateTransactionManager txManager = new HibernateTransactionManager();
	        txManager.setSessionFactory(sessionFactory().getObject());
	        return txManager;
	    }
	    
	    @Bean
	    public InternalResourceViewResolver jspViewResolver() {
	        InternalResourceViewResolver resolver= new InternalResourceViewResolver();
	        resolver.setPrefix("/views/");
	        resolver.setSuffix(".jsp");
	        return resolver;
	    } 
	   
	   
	   
	}

StudentApplication.java

package config;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class StudentApplication {

	public static void main(String[] args) {
		SpringApplication.run(StudentApplication.class, args);
	}

}

Create the entity class
Here, we are creating an Entity/POJO (Plain Old Java Object) class.

Student.java

package Model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="student")
public class Student {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int student_id;
	private String student_name;
	private String student_email;
	private String student_branch;
	public int getStudent_id() {
		return student_id;
	}
	public void setStudent_id(int student_id) {
		this.student_id = student_id;
	}
	public String getStudent_name() {
		return student_name;
	}
	public void setStudent_name(String student_name) {
		this.student_name = student_name;
	}
	public String getStudent_email() {
		return student_email;
	}
	public void setStudent_email(String student_email) {
		this.student_email = student_email;
	}
	public String getStudent_branch() {
		return student_branch;
	}
	public void setStudent_branch(String student_branch) {
		this.student_branch = student_branch;
	}

	
}

Create the DAO interface
Here, we are creating the DAO interface to perform database related operations.

Student_DAO.java

package DAO;

import java.util.List;

import Model.Student;

public interface Student_DAO {

	public boolean saveStudent(Student student);
	public List<Student> getStudents();
	public boolean deleteStudent(Student student);
	public List<Student> getStudentByID(Student student);
	public boolean updateStudent(Student student);
}

Create the DAO interface implementation class

Student_DAO_Imp.java

package DAO;

import java.util.List;


import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;


import Model.Student;

@Repository
public class Student_DAO_Imp  implements Student_DAO{

	@Autowired
	private SessionFactory sessionFactory;
	
	@Override
	public boolean saveStudent(Student student) {
		boolean status=false;
		try {
			sessionFactory.getCurrentSession().save(student);
			status=true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return status;
	}

	@Override
	public List<Student> getStudents() {
		Session currentSession = sessionFactory.getCurrentSession();
		Query<Student> query=currentSession.createQuery("from Student", Student.class);
		List<Student> list=query.getResultList();
		return list;
	}

	@Override
	public boolean deleteStudent(Student student) {
		boolean status=false;
		try {
			sessionFactory.getCurrentSession().delete(student);
			status=true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return status;
	}

	@Override
	public List<Student> getStudentByID(Student student) {
		Session currentSession = sessionFactory.getCurrentSession();
		Query<Student> query=currentSession.createQuery("from Student where student_id=:student_id", Student.class);
		query.setParameter("student_id", student.getStudent_id());
		List<Student> list=query.getResultList();
		return list;
	}

	@Override
	public boolean updateStudent(Student student) {
		boolean status=false;
		try {
			sessionFactory.getCurrentSession().update(student);
			status=true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return status;
	}
	
	

}

Create the service layer interface

Here, we are creating a service layer interface that acts as a bridge between DAO and Entity classes.

Student_Service.java

package Service;

import java.util.List;
import Model.Student;

public interface Student_Service {

	
	public boolean saveStudent(Student student);
	public List<Student> getStudents();
	public boolean deleteStudent(Student student);
	public List<Student> getStudentByID(Student student);
	public boolean updateStudent(Student student);
}

Create the service layer implementation class

Student_Service_Imp.java

package Service;

import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import DAO.Student_DAO;
import Model.Student;

@Service
@Transactional
public class Student_Service_Imp implements Student_Service {
 
	@Autowired
	private Student_DAO studentdao;
	
	@Override
	public boolean saveStudent(Student student) {
		return studentdao.saveStudent(student);
	}

	@Override
	public List<Student> getStudents() {
		return studentdao.getStudents();
	}

	@Override
	public boolean deleteStudent(Student student) {
		return studentdao.deleteStudent(student);
	}

	@Override
	public List<Student> getStudentByID(Student student) {
		return studentdao.getStudentByID(student);
	}

	@Override
	public boolean updateStudent(Student student) {
		return studentdao.updateStudent(student);
	}

}

Create the controller class

Controller.java

package Controller;

import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import Model.Student;
import Service.Student_Service;

@RestController
@CrossOrigin(origins="http://localhost:4200")
@RequestMapping(value="/api")
public class Controller {
	
	@Autowired
	private Student_Service studentservice;
	
	@PostMapping("save-student")
	public boolean saveStudent(@RequestBody Student student) {
		 return studentservice.saveStudent(student);
		
	}
	
	@GetMapping("students-list")
	public List<Student> allstudents() {
		 return studentservice.getStudents();
		
	}
	
	@DeleteMapping("delete-student/{student_id}")
	public boolean deleteStudent(@PathVariable("student_id") int student_id,Student student) {
		student.setStudent_id(student_id);
		return studentservice.deleteStudent(student);
	}

	@GetMapping("student/{student_id}")
	public List<Student> allstudentByID(@PathVariable("student_id") int student_id,Student student) {
		 student.setStudent_id(student_id);
		 return studentservice.getStudentByID(student);
		
	}
	
	@PostMapping("update-student/{student_id}")
	public boolean updateStudent(@RequestBody Student student,@PathVariable("student_id") int student_id) {
		student.setStudent_id(student_id);
		return studentservice.updateStudent(student);
	}
}

Edit application.properties file
Here, we are editing the application.properties file present inside the src/main/resources folder. The following file contains the configuration properties.

application.properties

# Database
db.driver= com.mysql.jdbc.Driver
db.url= jdbc:mysql://localhost:3306/indigo
db.username=root
db.password=

# Hibernate
hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.show_sql=true
hibernate.hbm2ddl.auto=update
entitymanager.packagesToScan=Model

Angular Module

Let's see the directory structure of Angular we need to follow:

Create an Angular project

Let's create an Angular project by using the following command:

ng new Angular

Here, Angular is the name of the project.

Install Bootstrap CSS framework

Use the following command to install bootstrap in the project.

npm install [email protected] --save

Now, include the following code in the style.css file.

Install Angular-DataTable

Use the following command to install angular datatable in the project.

npm install angular-datatable --save

It is required to include DataTableModule in imports array of app.module.ts file.

Generate Components
Open the project in visual studio and then use the following command to generate Angular components:
ng g c AddStudent
ng g c StudentList

Let's also create a service class by using the following command: -

ng g s Student

Edit the app.module.ts file
- Import Routing - Here, we are importing routing file (app-routing.module.ts) and include it in imports array.
- Import ReactiveFormsModule - Here, we are importing ReactiveFormsModule for reactive forms and specify it in imports array.
- Import HttpModule - Here, we are importing HttpModule for server requests and specifying it in imports array.
- Register Service class - Here, we are mentioning the service class in provider's array.

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import {DataTablesModule} from 'angular-datatables';
import { StudentListComponent } from './student-list/student-list.component';
import { AddStudentComponent } from './add-student/add-student.component';

@NgModule({
  declarations: [
    AppComponent,
    StudentListComponent,
    AddStudentComponent,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    ReactiveFormsModule,
    HttpClientModule,
    DataTablesModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Edit the app-routing.module.ts file

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { StudentListComponent } from './student-list/student-list.component';
import { AddStudentComponent } from './add-student/add-student.component';

const routes: Routes = [
  { path: '', redirectTo: 'view-student', pathMatch: 'full' },
  { path: 'view-student', component: StudentListComponent },
  { path: 'add-student', component: AddStudentComponent },
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Edit the app.component.html file

    <div  class="container-fluid">
    <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
        <ul class="navbar-nav">
          <li class="nav-item ">
            <a routerLink="view-student" class="nav-link" class="btn btn-primary active" role="button" >View Student</a>
          </li>�
          <li class="nav-item">
            <a  routerLink="add-student" class="nav-link" class="btn btn-primary active" role="button" >Add Student</a>
          </li>          
        </ul>
      </nav>   
        <router-outlet></router-outlet>
    </div>

Create the Student.ts class

Let's create a class by using the following command: -

ng g class Student

Now, specify the required fields within the Student class.

export class Student {

    student_id:number;
    student_name:String;
    student_email:String;
    student_branch:String;
}

The purpose of this class is to map the specified fields with the fields of Spring entity class.

Edit the student.service.ts file

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})

export class StudentService {

  private baseUrl = 'http://localhost:8080/api/';

  constructor(private http:HttpClient) { }

  getStudentList(): Observable<any> {
    return this.http.get(`${this.baseUrl}`+'students-list');
  }

  createStudent(student: object): Observable<object> {
    return this.http.post(`${this.baseUrl}`+'save-student', student);
  }

  deleteStudent(id: number): Observable<any> {
    return this.http.delete(`${this.baseUrl}/delete-student/${id}`, { responseType: 'text' });
  }

  getStudent(id: number): Observable<Object> {
    return this.http.get(`${this.baseUrl}/student/${id}`);
  }

  updateStudent(id: number, value: any): Observable<Object> {
    return this.http.post(`${this.baseUrl}/update-student/${id}`, value);
  }
  
}

Edit the add-student.component.ts file

import { Component, OnInit } from '@angular/core';
import { StudentService } from '../student.service';
import {FormControl,FormGroup,Validators} from '@angular/forms';
import { Student } from '../student';
@Component({
  selector: 'app-add-student',
  templateUrl: './add-student.component.html',
  styleUrls: ['./add-student.component.css']
})
export class AddStudentComponent implements OnInit {

  constructor(private studentservice:StudentService) { }

  student : Student=new Student();
  submitted = false;

  ngOnInit() {
    this.submitted=false;
  }

  studentsaveform=new FormGroup({
    student_name:new FormControl('' , [Validators.required , Validators.minLength(5) ] ),
    student_email:new FormControl('',[Validators.required,Validators.email]),
    student_branch:new FormControl()
  });

  saveStudent(saveStudent){
    this.student=new Student();   
    this.student.student_name=this.StudentName.value;
    this.student.student_email=this.StudentEmail.value;
    this.student.student_branch=this.StudentBranch.value;
    this.submitted = true;
    this.save();
  }

  

  save() {
    this.studentservice.createStudent(this.student)
      .subscribe(data => console.log(data), error => console.log(error));
    this.student = new Student();
  }

  get StudentName(){
    return this.studentsaveform.get('student_name');
  }

  get StudentEmail(){
    return this.studentsaveform.get('student_email');
  }

  get StudentBranch(){
    return this.studentsaveform.get('student_branch');
  }

  addStudentForm(){
    this.submitted=false;
    this.studentsaveform.reset();
  }
}

Edit the add-student.component.html file

<h3>Create Student</h3>
<div class="row">
  <div class="col-sm-4"></div>
  <div class="col-sm-4" >
    <div [hidden]="submitted" style="width: 400px;">
      <form [formGroup]="studentsaveform" #savestudent (ngSubmit)="saveStudent(saveStudent)">
          <div class="form-group">
              <label for="name">Student Name</label>
              <input type="text" class="form-control"  formControlName="student_name" data-toggle="tooltip" 
                 data-placement="right" title="Enter Student Name" >
              <div class="alert alert-danger" *ngIf = "(StudentName.touched) && (StudentName.invalid)" 
                style="margin-top: 5px;">
                  <span *ngIf="StudentName.errors.required">Student Name is Required</span>
                    <span *ngIf = "StudentName.errors.minlength"> 
                        MinLength Error 
                    </span>                   
                </div>
          </div>
  
          <div class="form-group">
              <label for="name">Student Email</label>
              <input type="text" class="form-control" formControlName="student_email" 
                data-toggle="tooltip" data-placement="right" title="Enter Student Email">
                <div class="alert alert-danger" *ngIf = "(StudentEmail.touched) && (StudentEmail.invalid)" 
                style="margin-top: 5px;">
                  <span *ngIf="StudentEmail.errors.required">Student Email is Required</span>
                    <span *ngIf = "StudentEmail.errors.email"> 
                        Invalid Email Format 
                    </span>                   
                </div>
          </div>
  
          <div class="form-group">
              <label for="branch">Student Branch</label>
                <select class="form-control" formControlName="student_branch" data-toggle="tooltip" 
                      data-placement="right" title="Select Student Branch">
                    <option value="null">--Select Branch--</option>
                  <option value="B-Tech">B-Tech</option>
                  <option value="BCA">BCA</option>
                  <option value="MCA">MCA</option>
                  <option value="M-Tech">M-Tech</option>
                </select>
          </div>
  
          <button type="submit" class="btn btn-success">Submit</button>
      </form>
  </div>
  </div>
  <div class="col-sm-4"></div>
</div>
<div class="row">
  <div class="col-sm-4"></div>
  <div class="col-sm-4">
      <div [hidden]="!submitted">
         <h4>Student Added SuccessFully!</h4>
         <button (click)="addStudentForm()" class='btn btn-primary'>Add More Student</button>
      </div>      
  </div>
  <div class="col-sm-4"></div>
</div>

On clicking Add Student, the following page generates:

Now, fill the required details and submit them to add student.

Edit the student-list.component.ts file

import { Component, OnInit } from '@angular/core';
import { StudentService } from '../student.service';
import { Student } from '../student';
import { Observable,Subject } from "rxjs";

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

@Component({
  selector: 'app-student-list',
  templateUrl: './student-list.component.html',
  styleUrls: ['./student-list.component.css']
})
export class StudentListComponent implements OnInit {

 constructor(private studentservice:StudentService) { }

  studentsArray: any[] = [];
  dtOptions: DataTables.Settings = {};
  dtTrigger: Subject<any>= new Subject();

  students: Observable<Student[]>;
  student : Student=new Student();
  deleteMessage=false;
  studentlist:any;
  isupdated = false;    
 

  ngOnInit() {
    this.isupdated=false;
    this.dtOptions = {
      pageLength: 6,
      stateSave:true,
      lengthMenu:[[6, 16, 20, -1], [6, 16, 20, "All"]],
      processing: true
    };   
    this.studentservice.getStudentList().subscribe(data =>{
    this.students =data;
    this.dtTrigger.next();
    })
  }
  
  deleteStudent(id: number) {
    this.studentservice.deleteStudent(id)
      .subscribe(
        data => {
          console.log(data);
          this.deleteMessage=true;
          this.studentservice.getStudentList().subscribe(data =>{
            this.students =data
            })
        },
        error => console.log(error));
  }

  updateStudent(id: number){
    this.studentservice.getStudent(id)
      .subscribe(
        data => {
          this.studentlist=data           
        },
        error => console.log(error));
  }

  studentupdateform=new FormGroup({
    student_id:new FormControl(),
    student_name:new FormControl(),
    student_email:new FormControl(),
    student_branch:new FormControl()
  });

  updateStu(updstu){
    this.student=new Student(); 
   this.student.student_id=this.StudentId.value;
   this.student.student_name=this.StudentName.value;
   this.student.student_email=this.StudentEmail.value;
   this.student.student_branch=this.StudentBranch.value;
   console.log(this.StudentBranch.value);
   

   this.studentservice.updateStudent(this.student.student_id,this.student).subscribe(
    data => {     
      this.isupdated=true;
      this.studentservice.getStudentList().subscribe(data =>{
        this.students =data
        })
    },
    error => console.log(error));
  }

  get StudentName(){
    return this.studentupdateform.get('student_name');
  }

  get StudentEmail(){
    return this.studentupdateform.get('student_email');
  }

  get StudentBranch(){
    return this.studentupdateform.get('student_branch');
  }

  get StudentId(){
    return this.studentupdateform.get('student_id');
  }

  changeisUpdate(){
    this.isupdated=false;
  }
}

Edit the student-list.component.html file

<div class="panel panel-default">
  <div class="panel-heading">
      <h1 style="text-align: center">Students</h1><br>
      <div class="row" [hidden]="!deleteMessage">
           
                <div class="col-sm-4"></div>
                <div class="col-sm-4">
                        <div class="alert alert-info alert-dismissible">
                                <button type="button" class="close" data-dismiss="alert">�</button>
                                <strong>Student Data Deleted</strong>
                        </div>
                </div>
                <div class="col-sm-4"></div>
        </div>           
    </div>

  
  <div class="panel-body">
      <table  class="table table-hover table-sm" datatable [dtOptions]="dtOptions"
      [dtTrigger]="dtTrigger"  >
          <thead class="thead-light">
              <tr>
                  <th>Student Name</th>
                  <th>Student Email</th>
                  <th>Student Branch</th>
                  <th>Action</th>
                  
              </tr>
          </thead>
          <tbody>
               <tr *ngFor="let student of students ">
                  <td>{{student.student_name}}</td>
                  <td>{{student.student_email}}</td>
                  <td>{{student.student_branch}}</td>
                  <td><button (click)="deleteStudent(student.student_id)" class='btn btn-primary'><i class="fa fa-futboll-0">Delete</i></button>�
                    <button (click)="updateStudent(student.student_id)" class='btn btn-info'
                    data-toggle="modal" data-target="#myModal">Update</button>
                  </td>
                </tr> 
          </tbody><br>
      </table>
  </div>
</div> 

<div class="modal" id="myModal">
        <div class="modal-dialog">
          <div class="modal-content">
                <form [formGroup]="studentupdateform" #updstu (ngSubmit)="updateStu(updstu)">
            <!-- Modal Header -->
            <div class="modal-header">
              <h4 class="modal-title" style="text-align: center">Update Student</h4>
              
            </div>
            
            <!-- Modal body -->
            <div class="modal-body" *ngFor="let student of studentlist " >
                <div [hidden]="isupdated">

                    <input type="hidden" class="form-control"  formControlName="student_id" [(ngModel)]="student.student_id">
                            <div class="form-group">
                                <label for="name">Student Name</label>
                                <input type="text" class="form-control"  formControlName="student_name" [(ngModel)]="student.student_name"  >
                            </div>
                    
                            <div class="form-group">
                                <label for="name">Student Email</label>
                                <input type="text" class="form-control" formControlName="student_email" [(ngModel)]="student.student_email">
                            </div>
                    
                            <div class="form-group">
                                <label for="name">Student Branch</label>
                                  <select class="form-control" formControlName="student_branch" required>                                   
                                    <option value="B-Tech" [selected]="'B-Tech' == student.student_branch">B-Tech</option>
                                    <option value="BCA" [selected]="'BCA' == student.student_branch">BCA</option>
                                    <option value="MCA" [selected]="'MCA' == student.student_branch" >MCA</option>
                                    <option value="M-Tech" [selected]="'M-Tech' == student.student_branch">M-Tech</option>
                                  </select>                               
                            </div>                   
                  </div>  
                  <div [hidden]="!isupdated">
                      <h4>Student Detail Updated!</h4>
                  </div>        
                    
            </div>
            
            <!-- Modal footer -->
            <div class="modal-footer" >
              <button type="submit" class="btn btn-success" [hidden]="isupdated">Update</button>
              <button type="button" class="btn btn-danger" data-dismiss="modal" (click)="changeisUpdate()">Close</button>
            </div>
            
        </form>
          </div>
        </div>
      </div>

On clicking View Student, the following page generates: