ASP.NET

public class HomeController : Controller
{
        public ActionResult Index(int? id)
        {
        }
}

routes.MapRoute(
    name: "Test",
    url: "MyUrl/{action}/{id}/{controller}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

public static async Task SeedAsync(IMongoDatabase _database)
{
    var websiteStates = _database.GetCollection<WEBSITE_STATES>("Website_States");

    // Check and see if we have any website users
    double totalDocuments = websiteStates.CountDocuments(FilterDefinition<WEBSITE_STATES>.Empty);
    if (totalDocuments == 0)
    {

        var websiteCountries = _database.GetCollection<WEBSITE_COUNTRIES>("Website_Countries");
        try
        {<br />
            foreach (var country in websiteCountries.FindSync(_ => true).ToListAsync().Result)
            {
                switch (country.ShortName)
                {
                    // United States
                    case "US":

                        // A
                        ObjectId US_AL_Id = ObjectId.GenerateNewId();
                        var state_AL = new WEBSITE_STATES() { Id = US_AL_Id, DisplayId = US_AL_Id.ToString(), CountryId = country.DisplayId,        CountryCode = country.ShortName, LongName = "Alabama", ShortName = "AL", Enabled = true };
                        await websiteStates.InsertOneAsync(state_AL);

// Let See if we can inject the States collection into Countries/States
var filter_US = Builders<WEBSITE_COUNTRIES>.Filter.Eq(s => s.ShortName, country.ShortName.ToUpper());
var update_US = Builders<WEBSITE_COUNTRIES>.Update.Set(s => s.States, states_US);
await websiteCountries.UpdateOneAsync(filter_US, update_US);

{
    "_id" : ObjectId("5b8434defb1e6524f8cc0554"),
    "DisplayId" : "5b8434defb1e6524f8cc0554",
    "LongName" : "United States",
    "ShortName" : "US",
    "States" : [ 
        {
            "_id" : ObjectId("5b8434dffb1e6524f8cc0582"),
            "Name" : "Alabama",
            "Abbr" : "AL"
        }, 
        {
            "_id" : ObjectId("5b8434dffb1e6524f8cc0583"),
            "Name" : "Alaska",
            "Abbr" : "AK"
        }, 
        {
            "_id" : ObjectId("5b8434dffb1e6524f8cc0583"),
            "Name" : "Arizona",
            "Abbr" : "AZ"
        }, 
        {
            "_id" : ObjectId("5b8434dffb1e6524f8cc0585"),
            "Name" : "Arkansas",
            "Abbr" : "AR"
        }, 

public void ConfigureServices(IServiceCollection services)
{
	services.AddMvc();
	services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

public class MyCustomHelper : IMyCustomHelper 
{
	private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly IUrlHelperFactory _urlHelperFactory;
 
	public MyCustomHelper(IHttpContextAccessor httpContextAccessor, IUrlHelperFactory urlHelperFactory)
	{
		_httpContextAccessor = httpContextAccessor;
        _urlHelperFactory = urlHelperFactory;
	}
 
	public string GetUrl()
	{
		var context = _httpContextAccessor.HttpContext;
		IUrlHelper urlHelper = urlHelperFactory.GetUrlHelper(context);
                //do stuff here
	}
}

1. Where should I put ConfigureServices method?
2. My current MVC5 custom helper like following:
   public static class HtmlHelperExt
   {
   
   public static IHtmlString CHGridTable<tmodel>(this HtmlHelper<tmodel> htmlHelper, DataTable dt, object htmlAttributes = null)
   {
   UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);
   string urlEdit = url.RouteUrl("Default");
   ......
   }
   ......//many other custom helpers
   }
   
   How can I inject the IActionContextAccessor and use it in my custom helper CHGridTable and other helpers?
3. How can I use the ContextAccessor to get info for the code lines below:
   UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);
   string urlEdit = url.RouteUrl("Default");

JimFeng wrote:

I'm new to ASP.NET Core and still have following questions:

1. Where should I put ConfigureServices method?

JimFeng wrote:

How can I inject the IActionContextAccessor and use it in my custom helper CHGridTable and other helpers?

public static class HtmlHelperExt{
    private static IHttpContextAccessor _httpContextAccessor;
    private static IUrlHelperFactory _urlHelperFactory;
    public static void SetHttpContextAccessor(IHttpContextAccessor  accessor, IUrlHelperFactory urlHelperFactory) {
        _httpContextAccessor = accessor;
        _urlHelperFactory = urlHelperFactory;
    }

    public static IHtmlString CHGridTable<tmodel>(this HtmlHelper<tmodel> htmlHelper, DataTable dt, object htmlAttributes = null)
    {
            var urlHelper = _urlHelperFactory.GetUrlHelper(_httpContextAccessor.HttpContext);
            string urlEdit = urlHelper.RouteUrl("Default");
            //rest of the stuff here
    }
}

public void ConfigureServices(IServiceCollection service) {

    services.AddMvc();

    //this would have been done by the framework any way after this method call;
    //in this case you call the BuildServiceProvider manually to be able to use it
    var serviceProvider = services.BuildServiceProvider();

    //here is where you set you accessor and url helper factory
    var accessor = serviceProvider.GetService<IHttpContextAccessor>()
    var userHelperFactory = serviceProvider.GetService<IUrlHelperFactory>()
    HtmlHelperExt.SetHttpContextAccessor(accessor,userHelperFactory);

  
}

var urlHelper = _urlHelperFactory.GetUrlHelper(_httpContextAccessor.HttpContext);

Argument 1: cannot convert from 'Microsoft.AspNetCore.Http.HttpContext' to 'Microsoft.AspNetCore.Mvc.ActionContext'

private static IActionContextAccessor _actionContextAccessor;
private static IUrlHelperFactory _urlHelperFactory;
public static void SetHttpContextAccessor(IActionContextAccessor accessor, IUrlHelperFactory urlHelperFactory) {
    _actionContextAccessor = accessor;
    _urlHelperFactory = urlHelperFactory;
}

var urlHelper = _urlHelperFactory.GetUrlHelper(_actionContextAccessor.ActionContext);

var accessor = serviceProvider.GetService<IActionContextAccessor>()
var userHelperFactory = serviceProvider.GetService<IUrlHelperFactory>()
HtmlHelperExt.SetHttpContextAccessor(accessor,userHelperFactory);