petTemplate = @You have a pet named @item.Name.
;
var pets = new object[]
{
new { Name = "Rin Tin Tin" },
new { Name = "Mr. Bigglesworth" },
new { Name = "K-9" }
};
}
@foreach (var pet in pets)
{
@petTemplate(pet)
}
@{
class ListPackage
{
public string[] ListItems { get; set; }
public string Style { get; set; }
}
Func template = @
@foreach (var listItem in item.ListItems)
{
- @listItem
}
;
}
@template(new ListPackage { ListItems = new[] { "A","B","C" }, Style = "pretty" })
@{
void Template(string[] listItems, string style)
{
foreach (var listItem in listItems)
{
- @listItem
}
}
}
@{ Template(new[] { "A","B","C" }, "pretty" ); }
[HttpGet]
[Route("get-edustandards")]
public virtual IActionResult GetEdustandards()
{
var model =
from level1 in _context.Levels
.Include(x => x.Slave_Directions)
.ThenInclude(x => x.Slave_Standards)
where !level1.IsDisabled
orderby level1.Group
select new
{
level1.Group,
level1.Title,
Directions =
from direction1 in level1.Slave_Directions
where !direction1.IsDisabledEdu
orderby direction1.Code
select new
{
direction1.Code,
direction1.Title,
Standards =
from standard1 in direction1.Slave_Standards
where !standard1.IsDisabledStandard
orderby standard1.Year
select new
{
standard1.Title,
standard1.Url,
standard1.Year
}
}
};
if (model == null)
return NotFound();
return Ok(model);
}
public IActionResult JsonTest()
{
return Json(new { Foo = 1, Goo = true, Koo = "Test" });
}
https://edi.wang/post/2018/10/31/migrating-old-aspnet-applications-to-net-core
6. Custom Http Headers
In classic ASP.NET, you could add custom http headers to each response via Web.Config like this
In .NET Core, if you need to host your application without Windows, you can’t use Web.config. So, you can do it via a third party NuGet package: NetEscapades.AspNetCore.SecurityHeaders
app.UseSecurityHeaders(new HeaderPolicyCollection()
.AddCustomHeader("X-UA-Compatible", "IE=edge")
.AddCustomHeader("X-Developed-By", "Edi Wang")
);
7. Get Client IP Address and HttpContext
In classic ASP.NET we used to get client IP Address by Request.UserHostAddress. But this does not apply to ASP.NET Core 2.x. We need a different way to retrieve HTTP Request information.
Define a variable in your MVC controller
private IHttpContextAccessor _accessor;
DI into the controller's constructor
public SomeController(IHttpContextAccessor accessor)
{
_accessor = accessor;
}
Retrive the IP Address
_accessor.HttpContext.Connection.RemoteIpAddress.ToString()
This is how it is done.
If your ASP.NET Core project is created with the default MVC template, you should have the DI for HttpContextAcccessor in Startup.cs
services.AddHttpContextAccessor();
services.TryAddSingleton();
The RemoteIpAddress is in type of IPAddress, not string. It contains IPv4, IPv6 and other information, it is not like the classic ASP.NET, which will be more useful to us.
If you want to access this information in Razor Views (cshtml). Just use @inject to DI into the view:
@inject Microsoft.AspNetCore.Http.IHttpContextAccessor HttpContextAccessor
and then use it in your razor page:
Client IP: @HttpContextAccessor.HttpContext.Connection.RemoteIpAddress.ToString()
12. Session and Cookie
Session is not enabled by default in ASP.NET Core, you must manually add the Session support.
services.AddDistributedMemoryCache();
services.AddSession(options =>
{
options.IdleTimeout = TimeSpan.FromMinutes(20);
options.Cookie.HttpOnly = true;
});
and
app.UseSession();
To get and set values:
HttpContext.Session.SetString("CaptchaCode", result.CaptchaCode);
HttpContext.Session.GetString("CaptchaCode");
To clear values:
context.Session.Remove("CaptchaCode");
Check more at https://docs.microsoft.com/en-us/aspnet/core/fundamentals/app-state?view=aspnetcore-2.1
16. Anti-Forgery Token
The anti-forgery token has a few improvements. First, you can customize cookie and field names now.
services.AddAntiforgery(options =>
{
options.Cookie.Name = "X-CSRF-TOKEN-MOONGLADE";
options.FormFieldName = "CSRF-TOKEN-MOONGLADE-FORM";
});
Second, you no longer need to manually add this code to every form.
@Html.AntiForgeryToken()
If you are using the new form tag helper, the anti-forgery field will be automatically added when your view is rendered to the client:
But you will still need to add [ValidateAntiForgeryToken] attribute to the corresponding Action.
However, there’s another way to Automatically validate anti-forgery tokens for every POST actions.
services.AddMvc(options =>
options.Filters.Add(new AutoValidateAntiforgeryTokenAttribute()));
Or you can do this to a specific Controller.
[Authorize]
[AutoValidateAntiforgeryToken]
public class ManageController : Controller
18. API Behavior Differences
Some code from classic ASP.NET will compile without error, but it does not guarantee runtime success. For example, this code from ASP.NET in .NET Framework will throw exception in ASP.NET Core:
var buffer = new byte[context.Request.Body.Length];
context.Request.Body.Read(buffer, 0, buffer.Length);
var xml = Encoding.Default.GetString(buffer);
It will result in
System.NotSupportedException: Specified method is not supported.
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpRequestStream.get_Length()
And we need to use a different way to do it in .NET Core:
var xml = await new StreamReader(context.Request.Body, Encoding.Default).ReadToEndAsync();
19. Watch out for the GDPR problem
ASP.NET Core 2.1 by default added the GDPR support, which can make some problems for us. You can check https://docs.microsoft.com/en-us/aspnet/core/security/gdpr?view=aspnetcore-2.1 for details.
The major problem is that Cookie won’t work until user accepts the GDPR policy. You need to check what cookie is essential for your website to work even the user hasn’t accept the GDPR policy and set them to IsEssential.
This is an example in my blog system:
private void SetPostTrackingCookie(CookieNames cookieName, string id)
{
var options = new CookieOptions
{
Expires = DateTime.UtcNow.AddDays(1),
SameSite = SameSiteMode.Strict,
Secure = Request.IsHttps,
// Mark as essential to pass GDPR
// https://docs.microsoft.com/en-us/aspnet/core/security/gdpr?view=aspnetcore-2.1
IsEssential = true
};
Response.Cookies.Append(cookieName.ToString(), id, options);
}
Another problem is if you are using Session, then you must make user accept GDPR policy, or it won’t work, because Session relies on Cookie to store the SessionID to client side.