在 ASP.NET Core MVC Web 应用程序中出现构造函数错误？

Question

I keep getting the error below when trying to pass my IEnumerable to the view.

I'm really puzzled in what is it, the return type of GetCandidates is IEnumerable<Candidate> .

InvalidOperationException: A suitable constructor for type 'System.Collections.Generic.ICollection`1[Models.Candidate]' could not be located. Ensure the type is concrete and all parameters of a public constructor are either registered as services or passed as arguments. Also ensure no extraneous arguments are provided.

My Candidate model class:

public class Candidate
{
    public Guid candidateId { get; set; }
    public string fullName { get; set; }
    public bool seen { get;set; }
    public bool status { get; set; }

    public IEnumerable<Experience> experience { get; set; }
}

My registered services:

builder.Services.AddHttpClient();
builder.Services.AddTransient<IApiService, ApiService>();
// other code //

My Index.cshtml view:

@page
@using Models

@model ICollection<Candidate>

@{
    ViewData["Title"] = "Home page";
}

//other code//

Answer 1

You need firstly learn how to get started in Razor Pages:

https://docs.microsoft.com/en-us/aspnet/core/razor-pages/?view=aspnetcore-6.0&tabs=visual-studio#razor-pages

Razor Pages do not use @model ModelName ,it uses @model <PageName>Model ,which is different from MVC.

Change your Index.cshtml like below:

@page

@model IndexModel

@{
    ViewData["Title"] = "Home page";
}
@foreach(var item in Model.Candidate)
{
    @item.fullName
}

The Index.cshtml.cs like below:

public class IndexModel : PageModel
{

    public List<Candidate> Candidate { get; set; }

    public void OnGet()
    {
        //for easy testing, I just hard-coded...
        Candidate = new List<Candidate>()
        {
            new Candidate(){fullName="aa"},
            new Candidate(){fullName="aa1"},
            new Candidate(){fullName="aa2"}
        };
        
    }
}