Revert "Remove old 2.0 PrincipalExtensions which are no longer needed"

This reverts commit 1c26e8f5fa.

src/Microsoft.AspNet.Identity/IUserClaimsPrincipalFactory.cs

@@ -17,6 +17,7 @@ namespace Microsoft.AspNet.Identity
         /// Creates a <see cref="ClaimsPrincipal"/> from an user asynchronously.
         /// </summary>
         /// <param name="user">The user to create a <see cref="ClaimsPrincipal"/> from.</param>
+        /// <param name="authenticationType">The name of the authentication method the <paramref name="user"/> was sourced from.</param>
         /// <returns>The <see cref="Task"/> that represents the asynchronous creation operation, containing the created <see cref="ClaimsPrincipal"/>.</returns>
         Task<ClaimsPrincipal> CreateAsync(TUser user);
     }

src/Microsoft.AspNet.Identity/PrincipalExtensions.cs

@@ -11,6 +11,36 @@ namespace System.Security.Claims
     /// </summary>
     public static class PrincipalExtensions
     {
+        /// <summary>
+        /// Returns the Name claim value if present otherwise returns null.
+        /// </summary>
+        /// <param name="principal">The <see cref="ClaimsPrincipal"/> instance this method extends.</param>
+        /// <returns>The Name claim value, or null if the claim is not present.</returns>
+        /// <remarks>The Name claim is identified by <see cref="ClaimsIdentity.DefaultNameClaimType"/>.</remarks>
+        public static string GetUserName(this ClaimsPrincipal principal)
+        {
+            if (principal == null)
+            {
+                throw new ArgumentNullException(nameof(principal));
+            }
+            return principal.FindFirstValue(ClaimsIdentity.DefaultNameClaimType);
+        }
+
+        /// <summary>
+        /// Returns the User ID claim value if present otherwise returns null.
+        /// </summary>
+        /// <param name="principal">The <see cref="ClaimsPrincipal"/> instance this method extends.</param>
+        /// <returns>The User ID claim value, or null if the claim is not present.</returns>
+        /// <remarks>The User ID claim is identified by <see cref="ClaimTypes.NameIdentifier"/>.</remarks>
+        public static string GetUserId(this ClaimsPrincipal principal)
+        {
+            if (principal == null)
+            {
+                throw new ArgumentNullException(nameof(principal));
+            }
+            return principal.FindFirstValue(ClaimTypes.NameIdentifier);
+        }
+
         /// <summary>
         /// Returns true if the principal has an identity with the application cookie identity
         /// </summary>
@@ -22,7 +52,7 @@ namespace System.Security.Claims
             {
                 throw new ArgumentNullException(nameof(principal));
             }
-            return principal.Identities != null && 
+            return principal?.Identities != null && 
                 principal.Identities.Any(i => i.AuthenticationType == IdentityCookieOptions.ApplicationCookieAuthenticationType);
         }
 

src/Microsoft.AspNet.Identity/SecurityStampValidator.cs

@@ -26,7 +26,7 @@ namespace Microsoft.AspNet.Identity
         public virtual async Task ValidateAsync(CookieValidatePrincipalContext context)
         {
             var manager = context.HttpContext.RequestServices.GetRequiredService<SignInManager<TUser>>();
-            var userId = context.Principal.FindFirstValue(manager.Options.ClaimsIdentity.UserIdClaimType);
+            var userId = context.Principal.GetUserId();
             var user = await manager.ValidateSecurityStampAsync(context.Principal, userId);
             if (user != null)
             {

test/Microsoft.AspNet.Identity.Test/PrincipalExtensionsTest.cs

@@ -15,9 +15,19 @@ namespace Microsoft.AspNet.Identity.Test
         public void IdentityNullCheckTest()
         {
             ClaimsPrincipal p = null;
+            Assert.Throws<ArgumentNullException>("principal", () => p.GetUserId());
+            Assert.Throws<ArgumentNullException>("principal", () => p.GetUserName());
             Assert.Throws<ArgumentNullException>("principal", () => p.FindFirstValue(null));
         }
 
+        [Fact]
+        public void UserNameAndIdTest()
+        {
+            var p = CreateTestExternalIdentity();
+            Assert.Equal("NameIdentifier", p.GetUserId());
+            Assert.Equal("Name", p.GetUserName());
+        }
+
         [Fact]
         public void IdentityExtensionsFindFirstValueNullIfUnknownTest()
         {

test/Microsoft.AspNet.Identity.Test/SecurityStampValidatorTest.cs

@@ -40,14 +40,13 @@ namespace Microsoft.AspNet.Identity.Test
             var userManager = MockHelpers.MockUserManager<TestUser>();
             var claimsManager = new Mock<IUserClaimsPrincipalFactory<TestUser>>();
             var identityOptions = new IdentityOptions { SecurityStampValidationInterval = TimeSpan.Zero };
-            identityOptions.ClaimsIdentity.UserIdClaimType = "IdClaim";
             var options = new Mock<IOptions<IdentityOptions>>();
             options.Setup(a => a.Value).Returns(identityOptions);
             var httpContext = new Mock<HttpContext>();
             var contextAccessor = new Mock<IHttpContextAccessor>();
             contextAccessor.Setup(a => a.HttpContext).Returns(httpContext.Object);
             var id = new ClaimsIdentity(identityOptions.Cookies.ApplicationCookieAuthenticationScheme);
-            id.AddClaim(new Claim(identityOptions.ClaimsIdentity.UserIdClaimType, user.Id));
+            id.AddClaim(new Claim(ClaimTypes.NameIdentifier, user.Id));
             var principal = new ClaimsPrincipal(id);
 
             var properties = new AuthenticationProperties { IssuedUtc = DateTimeOffset.UtcNow, IsPersistent = isPersistent };