Tag: Dependency Injection

Categories
ASP.NET Core

Service Injection into View in ASP.NET Core

Service Injection into View in ASP.NET Core

This blog is about how dependency is injected directly into view. Let us look at it using a small example.

The following is a ColorListService class that returns a list of strings.

Note

Put all your services in a separate folder called Services. So this will help you maintain a project structure

ColorListService.cs

public class ColorListService
{
    public List<string> GetColors()
    {
        return new List<string>() { “Red”, “Blue”, “Green”, “Yellow”, “Violet” };
    }
}

Before you can use a service, you must register for the service. See ASP.NET Service Scope for more information

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<ColorListService>();
    services.AddControllersWithViews();
}

The following is a view code. Here the ColorListService is injected using @Inject Directive. Finally a list of colors is listed using foreach.

ServiceDemo.cshtml

@{
    Layout = null;
    ViewData[“Title”] = “Service Injection into View”;
}

@inject SampleMVCApplication.Services.ColorListService  colors

<h4>Service Injection into View in ASP.NET Core</h4>

@foreach (string item in colors.GetColors())
{
    <div>@item</div>
}

Below is a HomeController code. It has a ServiceDemo() action which will render a ServiceDemo view.

HomeController.cs

public class HomeController : Controller
{
    public IActionResult ServiceDemo()
    {
         return View();
    }
}

The following is the output of the above code

Service Injection into View

This blog explains how to inject the service directly into the view with a small example.

If you have any questions, please leave a comment below.

Categories
ASP.NET Core

Populating Dropdown using Dependency Injection into View in ASP.NET Core

Dependency Injection

This blog explains how to load a drop-down list in View using a dependency injection, without passing the value from the controller. So that it will reduce the request to the controller. Let us see how to achieve this.

In this blog I have explained two types of drop-down list loading methods. The first one is a list of classes,  the second one is a list of strings. The following are Metals and OptionServices classes. The OptionServices provide a list of colors and a list of metal information (metal name and symbol)

 public class Metals
 {
  public string MetalName { get; set; }
  public string Symbol { get; set; }
 }

 public class OptionServices
 {
  public List<Metals> ListMetals()
  {
    return new List<Metals>()
    {
     new Metals(){ MetalName= “Gold”, Symbol=”Au” },
     new Metals(){ MetalName= “Platinum”, Symbol=”Pt” },
     new Metals(){ MetalName= “Silver”, Symbol=”Ag” }
    };
  }

  public List<string> ListColors()
  {
    return new List<string>() { “Red”, “Blue”, “Green”, “Yellow”, “Violet” };
  }
 }

To use the service, you must register the service in the ConfigureServices  method in the Startup.cs file.

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<OptionServices>();
    services.AddControllersWithViews();
}

The one below is the view code. Here I have injected the OptionServices  into view and loaded it into the dropdown list

PopulateDropDown.cshtml

@using SampleMVCWebApplication.Services
@inject OptionServices  Options

<h4>Populate Drop Down List</h4>

Select a Metal: @Html.DropDownList(“metal”, Options.ListMetals().Select(c => new SelectListItem() { Text = c.MetalName, Value = c.Symbol }))

<br />
<br />

Select a Color: @Html.DropDownList(“color”, Options.ListColors().Select(c => new SelectListItem() { Text = c, Value = c }))

The following is a controller code. We do not need to pass any values here to load the drop-down list

public class HomeController : Controller
{
    public IActionResult PopulateDropDown()
    {
        return View();
    }
}

The following is an output of the above code.

Populating-Dropdown

This article explains how to load the dropdown using service with a small example.

If you have any questions about this please leave a comment below.