Count calls to method with Dependency Injection

Mr.Jones Published at Dev

Mr.Jones

I'm trying to learn about dependency injection. I'm using .net 6.0 Razor Pages and I want to "count", the number of times a method is called via dependency injection. My Index is as following:

public class IndexModel : PageModel
{
    public ICounter _counter;

    public IndexModel(ICounter counter)
    {
        _counter = counter;
    }
    public int Count { get; set; }
    public void OnPostInfo()
    {
        Count = _counter.Calls(Count);
    }
}

My "counter" class, is as following

public int Number { get; set; }
public int Calls(int Number)
{
    return Number += 1 ;
}

And my interface

public interface ICounter
{
   int Calls(int Number);     
}

My Program.cs class

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages();
builder.Services.AddSingleton<ICounter, Counter>();

My View.

<div class="card">
    <div class="card-body">
        @Model.Count
    </div>
</div>
<div class="row">
    <form asp-page-handler="Info" method="post">
        <button class="btn btn-default">Push to count</button>
    </form>
</div>

It's added as an Transient in Program.cs. The site is updated via a button, and that "works", but it only updates to 1. But then it stops. It doesn't continue to "2, 3, 4" etc when i push the button that uses the OnPostInfo method.

What am i missing here?

Rena

Actually it is not caused by lifetime. It dues to the Count value is not passed to the backend, so backend will always get the int default value 0 for Count.

You need set a hidden input or route parameter to pass the Count.

First way to set a hidden input:

View:

<div class="card">
    <div class="card-body">
        @Model.Count
    </div>
</div>
<div class="row">
    <form asp-page-handler="Info" method="post">
        <input hidden asp-for="Count" value="@Model.Count" /> <!--set the hidden input-->
        <button class="btn btn-default">Push to count</button>
    </form>
</div>

PageModel:

public class IndexModel : PageModel
{
    public ICounter _counter;

    public IndexModel(ICounter counter)
    {

        _counter = counter;
    }
    [BindProperty]  //add this attribute to get the Count value
    public int Count { get; set; }
    public void OnPostInfo()
    {
        Count = _counter.Calls(Count);
    }
}

The second way to set a route parameter:

View:

<div class="card">
    <div class="card-body">
        @Model.Count
    </div>
</div>
<div class="row">                  <!--add asp-route-countNum -->
    <form asp-page-handler="Info" asp-route-countNum="@Model.Count" method="post">
        <button class="btn btn-default">Push to count</button>
    </form>
</div>

PageModel:

public class IndexModel : PageModel
{
    public ICounter _counter;

    public IndexModel(ICounter counter)
    {

        _counter = counter;
    }

    public int Count { get; set; }
    public void OnPostInfo(int countNum)   //add parameter here
    {
        Count = _counter.Calls(countNum);   //change here... 
    }
}

Result:

Collected from the Internet

Please contact [email protected] to delete if infringement.

edited at2021-11-27

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