Hogyan készítsünk egyoldalas alkalmazást a Razor oldalak használatával a Blazorral

Ebben a cikkben a Blazor Razor oldalainak felhasználásával létrehozunk egyoldalas alkalmazást (SPA), az Entity Framework Core adatbázis első megközelítésének segítségével.

Bevezetés

Az Single Page Application (SPA) olyan webalkalmazás, amely egyetlen HTML oldalt tölt be, és dinamikusan frissíti az oldalt, amikor a felhasználó interakcióba lép az alkalmazással. Létrehozunk egy mintát az alkalmazottak nyilvántartási rendszeréről, és CRUD műveleteket hajtunk végre rajta.

A Visual Studio 2017-t és az SQL Server 2014-et fogjuk használni.

Vessen egy pillantást a végleges jelentkezésre.

Előfeltételek

  • innen telepítse a .NET Core 2.1 Preview 2 SDK-t
  • innen telepítse a Visual Studio 2017 v15.7 vagy újabb verzióját
  • innen telepítse az ASP.NET Core Blazor Language Services kiterjesztést
  • SQL Server 2008 vagy újabb

A Blazor keretrendszert a Visual Studio 2017 v15.7 alatti verziók nem támogatják.

Forráskód

Szerezze be a forráskódot a GitHub-ból.

A táblázat létrehozása

DB táblát fogunk használni az alkalmazottak összes nyilvántartásának tárolására.

Nyissa meg az SQL Server szolgáltatást, és a következő szkript segítségével hozza létre a Employeetáblázatot.

CREATE TABLE Employee ( EmployeeID int IDENTITY(1,1) PRIMARY KEY, Name varchar(20) NOT NULL , City varchar(20) NOT NULL , Department varchar(20) NOT NULL , Gender varchar(6) NOT NULL )

Hozza létre a Blazor webalkalmazást

Nyissa meg a Visual Studio alkalmazást, és válassza a „Fájl”> „Új”> „Projekt” lehetőséget.

A projekt kiválasztása után megnyílik az „Új projekt” párbeszédpanel. A bal oldali panelen válassza a „.NET Core” elemet a Visual C # menüben. Ezután válassza ki az „ASP.NET Core Web Application” lehetőséget a rendelkezésre álló projekttípusok közül. Tegye a projekt nevét „BlazorSPA” névreés nyomja meg az „OK” gombot.

Az „OK” gombra kattintás után megnyílik egy új párbeszédpanel, amelyben a projekt sablonjának kiválasztását kéri. A sablonablak bal felső sarkában két legördülő menü látható. Válassza a „.NET Core” és az „ASP.NET Core 2.0” lehetőséget ezekből a legördülő listákból. Ezután válassza ki a „Blazor (ASP.NET Core hosted)” sablont, és nyomja meg az „OK” gombot.

Most elkészül a Blazor megoldásunk. Megfigyelheti a mappaszerkezetet a Solution Explorerben, az alábbi képen látható módon.

Megfigyelheti, hogy három projektfájlt hoztunk létre a megoldás belsejében.

  1. BlazorSPA.Client - rendelkezik az ügyféloldali kóddal, és tartalmazza a böngészőben megjelenített oldalakat.
  2. BlazorSPA.Server - rendelkezik olyan szerveroldali kódokkal, mint a DB-vel kapcsolatos műveletek és a webes API.
  3. BlazorSPA.Shared - tartalmazza a megosztott kódot, amelyhez kliens és szerver is hozzáférhet. Ez tartalmazza a modellosztályainkat.

A modell állványozása az alkalmazáshoz

A modellek létrehozásához az Entity Framework alapadatbázis első megközelítést alkalmazzuk. A „BlazorSPA.Shared” projektben létrehozzuk modellosztályunkat, hogy az mind az ügyfél, mind a szerver projekt számára elérhető legyen.

Keresse meg az „Eszközök”> „NuGet Package Manager”> „Package Manager Console” elemeket. Az „Alapértelmezett projekt” legördülő menüből válassza a „BlazorSPA.Shared” lehetőséget. Lásd az alábbi képet:

Először telepítjük a célzott adatbázis-szolgáltató csomagját, amely ebben az esetben az SQL Server. Futtassa a következő parancsot:

Install-Package Microsoft.EntityFrameworkCore.SqlServer

Mivel az Entity Framework Tools segítségével modellt készítünk a meglévő adatbázisból, telepítjük az tools csomagot is. Futtassa a következő parancsot:

Install-Package Microsoft.EntityFrameworkCore.Tools

Miután telepítette mindkét csomagot, a következő paranccsal állítjuk össze modellünket az adatbázis táblákból:

Scaffold-DbContext "Your connection string here" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Tables Employee

Ne felejtsen el saját kapcsolati karakterláncot elhelyezni (belül “”). A parancs sikeres végrehajtása után megfigyelheti a „Modellek” mappa létrehozását. Két osztályfájlt tartalmaz, a „myTestDBContext.cs”és az „Employee.cs”. Ezért sikeresen állványoztuk modelljeinket az Entity Framework magadatbázis első megközelítéssel.

Ekkor a Modellek mappa a következő felépítésű lesz:

Az alkalmazáshoz való adatelérési réteg létrehozása

Kattintson a jobb gombbal a „BlazorSPA.Server” projektre, majd válassza az „Hozzáadás”> „Új mappa” lehetőséget, és nevezze el a mappát „DataAccess” néven. Osztályunkat úgy fogjuk felvenni, hogy csak ebben a mappában belül kezelje az adatbázishoz kapcsolódó műveleteket.

Kattintson a jobb gombbal a „DataAccess” mappára, és válassza az „Hozzáadás”> „Osztály” lehetőséget. Nevezze el osztályát „EmployeeDataAccessLayer.cs” néven.

Nyissa meg az “EmployeeDataAccessLayer.cs” fájltand put the following code into it:

using BlazorSPA.Shared.Models;using Microsoft.EntityFrameworkCore;using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace BlazorSPA.Server.DataAccess{ public class EmployeeDataAccessLayer { myTestDBContext db = new myTestDBContext(); //To Get all employees details public IEnumerable GetAllEmployees() { try { return db.Employee.ToList(); } catch { throw; } } //To Add new employee record public void AddEmployee(Employee employee) { try { db.Employee.Add(employee); db.SaveChanges(); } catch { throw; } } //To Update the records of a particluar employee public void UpdateEmployee(Employee employee) { try { db.Entry(employee).State = EntityState.Modified; db.SaveChanges(); } catch { throw; } } //Get the details of a particular employee public Employee GetEmployeeData(int id) { try { Employee employee = db.Employee.Find(id); return employee; } catch { throw; } } //To Delete the record of a particular employee public void DeleteEmployee(int id) { try { Employee emp = db.Employee.Find(id); db.Employee.Remove(emp); db.SaveChanges(); } catch { throw; } } }}

Here we have defined methods to handle database operations. GetAllEmployees will fetch all the employee data from the Employee Table. Similarly, AddEmployee will create a new employee record, and UpdateEmployee will update the record of an existing employee. GetEmployeeData will fetch the record of the employee corresponding to the employee ID passed to it, and DeleteEmployee will delete the employee record corresponding to the employee ID passed to it.

Adding the web API controller to the application

Right click on the “BlazorSPA.Server/Controllers” folder and select “Add” > “New Item”. An “Add New Item” dialog box will open. Select “ASP.NET” from the left panel, then select “API Controller Class” from the templates panel, and put the name as “EmployeeController.cs”. Click “Add”.

This will create our API EmployeeControllerclass.

We will call the methods of theEmployeeDataAccessLayerclass to fetch data and pass on the data to the client side.

Open “EmployeeController.cs”file and put the following code into it:

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using BlazorSPA.Server.DataAccess;using BlazorSPA.Shared.Models;using Microsoft.AspNetCore.Mvc;namespace BlazorSPA.Server.Controllers{ public class EmployeeController : Controller { EmployeeDataAccessLayer objemployee = new EmployeeDataAccessLayer(); [HttpGet] [Route("api/Employee/Index")] public IEnumerable Index() { return objemployee.GetAllEmployees(); } [HttpPost] [Route("api/Employee/Create")] public void Create([FromBody] Employee employee) { if (ModelState.IsValid) objemployee.AddEmployee(employee); } [HttpGet] [Route("api/Employee/Details/{id}")] public Employee Details(int id) { return objemployee.GetEmployeeData(id); } [HttpPut] [Route("api/Employee/Edit")] public void Edit([FromBody]Employee employee) { if (ModelState.IsValid) objemployee.UpdateEmployee(employee); } [HttpDelete] [Route("api/Employee/Delete/{id}")] public void Delete(int id) { objemployee.DeleteEmployee(id); } }}

At this point of time, our “BlazorSPA.Server” project has the following structure.

We are done with our backend logic. Therefore, we will now proceed to code our client side.

Adding the Razor page to the application

We will add the Razor page into the “BlazorSPA.Client/Pages” folder. By default, we have “Counter” and “Fetch Data” pages provided in our application. These default pages will not affect our application but, for the sake of this tutorial, we will delete the “fetchdata”and “counter” pages from the “BlazorSPA.Client/Pages” folder.

Right click on the “BlazorSPA.Client/Pages” folder and then select “Add” > “New Item”. An “Add New Item” dialog box will open. Select “ASP.NET Core” from the left panel, then select “Razor Page” from the templates panel and name it “EmployeeData.cshtml”. Click “Add”.

This will add an “EmployeeData.cshtml” page to our “BlazorSPA.Client/Pages” folder. This Razor page will have two files, “EmployeeData.cshtml”andEmployeeData.cshtml.cs”.

Now we will add code to these pages.

EmployeeData.cshtml.cs

Open “EmployeeData.cshtml.cs”and put the following code into it:

using System;using System.Collections.Generic;using System.Linq;using System.Net.Http;using System.Threading.Tasks;using BlazorSPA.Shared.Models;using Microsoft.AspNetCore.Blazor;using Microsoft.AspNetCore.Blazor.Components;using Microsoft.AspNetCore.Blazor.Services;namespace BlazorSPA.Client.Pages{ public class EmployeeDataModel : BlazorComponent { [Inject] protected HttpClient Http { get; set; } [Inject] protected IUriHelper UriHelper { get; set; } [Parameter] protected string paramEmpID { get; set; } = "0"; [Parameter] protected string action { get; set; } protected List empList = new List(); protected Employee emp = new Employee(); protected string title { get; set; } protected override async Task OnParametersSetAsync() { if (action == "fetch") { await FetchEmployee(); this.StateHasChanged(); } else if (action == "create") { title = "Add Employee"; emp = new Employee(); } else if (paramEmpID != "0") { if (action == "edit") { title = "Edit Employee"; } else if (action == "delete") { title = "Delete Employee"; } emp = await Http.GetJsonAsync("/api/Employee/Details/" + Convert.ToInt32(paramEmpID)); } } protected async Task FetchEmployee() { title = "Employee Data"; empList = await Http.GetJsonAsync
    
     ("api/Employee/Index"); } protected async Task CreateEmployee() { if (emp.EmployeeId != 0) { await Http.SendJsonAsync(HttpMethod.Put, "api/Employee/Edit", emp); } else { await Http.SendJsonAsync(HttpMethod.Post, "/api/Employee/Create", emp); } UriHelper.NavigateTo("/employee/fetch"); } protected async Task DeleteEmployee() { await Http.DeleteAsync("api/Employee/Delete/" + Convert.ToInt32(paramEmpID)); UriHelper.NavigateTo("/employee/fetch"); } protected void Cancel() { title = "Employee Data"; UriHelper.NavigateTo("/employee/fetch"); } }}
    

Let us understand this code. We have defined a class EmployeeDataModelthat will hold all our methods that we will use in the “EmployeeData.cshtml”page.

We are injecting the HttpClient service to enable web API call and the IUriHelper service to enable URL redirection. After this, we have defined our parameter attributes — paramEmpID and action. These parameters are used in “EmployeeData.cshtml” to define the routes for our page. We have also declared a property title to display the heading to specify the current action that is being performed on the page.

The OnParametersSetAsync method is invoked every time the URL parameters are set for the page. We will check the value of parameter action to identify the current operation on the page.

If the action is set to fetch, then we will invoke the FetchEmployee method to fetch the updated list of employees from the database and refresh the UI using the StateHasChanged method.

We will check if the action attribute of parameter is set to create, then we will set the title of the page to “Add Employee” and create a new object of type Employee. If the paramEmpID is not “0”, then it is either an edit action or a delete action. We will set the title property accordingly and then invoke our web API method to fetch the data for the employee ID as set in the paramEmpID property.

The method FetchEmployee will set the title to “Employee Data” and fetch all the employee data by invoking our web API method.

The CreateEmployee method will check if it is invoked to add a new employee record, or to edit an existing employee record. If the EmployeeId property is set, then it is an edit request and we will send a PUT request to the web API. If EmployeeId is not set, then it is a create request and we will send a POST request to web API. We will set the title property according to the corresponding value of action, and then invoke our web API method to fetch the data for the employee ID as set in the paramEmpIDproperty.

The DeleteEmployee method will delete the employee record for the employee ID as set in the paramEmpID property. After deletion, the user is redirected to the “/employee/fetch” page.

In the Cancel method, we will set the title property to “Employee Data” and redirect the user to “/employee/fetch” page.

EmployeeData.cshtml

Open the “EmployeeData.cshtml” page and put the following code into it:

@page "/employee/{action}/{paramEmpID}"@page "/employee/{action}"@inherits EmployeeDataModel

@title

@if (action == "fetch"){

Create New

}@if (action == "create" || action == "edit"){
Name Department
Gender -- Select Gender -- Male Female City
await CreateEmployee())" value="Save" />
}else if (action == "delete"){
Name @emp.Name
Gender @emp.Gender
Department @emp.Department
City @emp.City
await DeleteEmployee())" value="Delete" /> }@if (empList == null){

Loading...

}else{ @foreach (var emp in empList)
ID Name Gender Department City
@emp.EmployeeId @emp.Name @emp.Gender @emp.Department @emp.City Edit
}

At the top, we have defined the routes for our page. There are two routes defined:

  1. /employee/{action}/{paramEmpID} : This will accept the action name along with employee ID. This route is invoked when we perform an Edit or Deleteoperation. When we call an edit or delete action on a particular employee’s data, the employee ID is also passed as the URL parameter.
  2. /employee/{action} : This will only accept the action name. This route is invoked when we create a new employee’s data, or we fetch the records of all the employees.

We are also inheriting theEmployeeDataModel class, which is defined in the “EmployeeData.cshtml.cs” file. This will allow us to use the methods defined in the EmployeeDataModel class.

After this, we are setting the title that will be displayed on our page. The title is dynamic and changes as per the action that is being executed currently on the page.

We will show the “Create New” link only if the action is fetch. If the action is create or edit then the “Create New” link will be hidden and we will display the form to get the user input. Inside the form, we have also defined the two buttons “Save” and “Cancel”. Clicking on “Save” will invoke the CreateEmployee method whereas clicking on “Cancel” will invoke the Cancel method.

If the action is delete then a table will be displayed with the data of the employee on which the delete action is invoked. We are also displaying two buttons — “Delete” and “Cancel”. Clicking on the “Delete” button will invoke the DeleteEmployee method, and clicking on “Cancel” will invoke the Cancel method.

At the end, we have a table to display all the employee data from the database. Each employee record will also have two action links: “Edit” to edit the employee record and “Delete” to delete the employee record. This table is always displayed on the page, and we will update it after performing every action.

Adding the link to the Navigation menu

The last step is to add the link to our “EmployeeData” page in the navigation menu. Open the “BlazorSPA.Client/Shared/NavMenu.cshtml” page and put the following code into it:

 BlazorSPA 
    
  • Home
  • Employee data
@functions { bool collapseNavMenu = true; void ToggleNavMenu() { collapseNavMenu = !collapseNavMenu; }}

Hence, we have successfully created an SPA using Blazor, with the help of the Entity Framework Core database first approach.

Execution demo

Launch the application.

A web page will open as shown in the image below. The navigation menu on the left is showing the navigation link for the Employee data page.

Clicking on the “Employee data” link will redirect to the “Employee Data” view. Here you can see all the employee data on the page. Notice the URL has “employee/fetch” appended to it.

We have not added any data, hence it is empty. Click on “CreateNew” to open the “Add Employee” form to add new employee data. Notice the URL has “employee/create” appended to it:

After inserting data in all the fields, click on the “Save” button. The new employee record will be created, and the Employee data table will get refreshed.

If we want to edit an existing employee record, then click on the “Edit” action link. It will open Edit view as shown below. Here we can change the employee data. Notice that we have passed the employee ID in the URL parameter.

Here we have changed the City of employee Swati from Mumbai to Kolkatta. Click on “Save” to refresh the employee data table to view the updated changes as highlighted in the image below:

Now we will perform a Delete operation on the employee named Dhiraj. Click on the “Delete” action link, which will open the Delete view asking for a confirmation to delete. Notice that we have passed the employee ID in the URL parameter.

Once we click on the “Delete” button, it will delete the employee record and the employee data table will be refreshed. Here, we can see that the employee with name Dhiraj has been removed from our record.

Deploying the application

To learn how to deploy a Blazor application using IIS, refer to Deploying A Blazor Application On IIS.

Conclusion

We have created a Single Page Application with Razor pages in Blazor using the Entity Framework Core database first approach with the help of Visual Studio 2017 and SQL Server 2014. We have also performed the CRUD operations on our application.

Please get the source code from GitHub and play around to get a better understanding.

Get my book Blazor Quick Start Guide to learn more about Blazor.

You can also read this article at C# Corner

You can check my other articles on Blazor here.

See Also

  • ASP.NET Core — Getting Started With Blazor
  • ASP.NET Core — CRUD Using Blazor And Entity Framework Core
  • Cascading DropDownList In Blazor Using EF Core
  • Razor Page Web Application With ASP.NET Core Using ADO.NET
  • ASP.NET Core — CRUD Using Angular 5 And Entity Framework Core
  • ASP.NET Core — CRUD With React.js And Entity Framework Core

Originally published at //ankitsharmablogs.com/