Merge remote-tracking branch 'origin/release/5.0-preview8' into merge/release/5.0-preview8-to-master

src/Mvc/Mvc.Core/src/Builder/ControllerEndpointRouteBuilderExtensions.cs

@@ -473,6 +473,36 @@ namespace Microsoft.AspNetCore.Builder
                 throw new ArgumentNullException(nameof(endpoints));
             }
 
+            MapDynamicControllerRoute<TTransformer>(endpoints, pattern, state: null);
+        }
+
+        /// <summary>
+        /// Adds a specialized <see cref="RouteEndpoint"/> to the <see cref="IEndpointRouteBuilder"/> that will
+        /// attempt to select a controller action using the route values produced by <typeparamref name="TTransformer"/>.
+        /// </summary>
+        /// <param name="endpoints">The <see cref="IEndpointRouteBuilder"/> to add the route to.</param>
+        /// <param name="pattern">The URL pattern of the route.</param>
+        /// <param name="state">A state object to provide to the <typeparamref name="TTransformer" /> instance.</param>
+        /// <typeparam name="TTransformer">The type of a <see cref="DynamicRouteValueTransformer"/>.</typeparam>
+        /// <remarks>
+        /// <para>
+        /// This method allows the registration of a <see cref="RouteEndpoint"/> and <see cref="DynamicRouteValueTransformer"/>
+        /// that combine to dynamically select a controller action using custom logic.
+        /// </para>
+        /// <para>
+        /// The instance of <typeparamref name="TTransformer"/> will be retrieved from the dependency injection container.
+        /// Register <typeparamref name="TTransformer"/> as transient in <c>ConfigureServices</c>. Using the transient lifetime
+        /// is required when using <paramref name="state" />.
+        /// </para>
+        /// </remarks>
+        public static void MapDynamicControllerRoute<TTransformer>(this IEndpointRouteBuilder endpoints, string pattern, object state)
+            where TTransformer : DynamicRouteValueTransformer
+        {
+            if (endpoints == null)
+            {
+                throw new ArgumentNullException(nameof(endpoints));
+            }
+
             EnsureControllerServices(endpoints);
 
             // Called for side-effect to make sure that the data source is registered.
@@ -486,7 +516,7 @@ namespace Microsoft.AspNetCore.Builder
                 })
                 .Add(b =>
                 {
-                    b.Metadata.Add(new DynamicControllerRouteValueTransformerMetadata(typeof(TTransformer)));
+                    b.Metadata.Add(new DynamicControllerRouteValueTransformerMetadata(typeof(TTransformer), state));
                 });
         }
 

src/Mvc/Mvc.Core/src/Resources.resx

@@ -519,4 +519,7 @@
   <data name="ValidationVisitor_ContainerCannotBeSpecified" xml:space="preserve">
     <value>A container cannot be specified when the ModelMetada is of kind '{0}'.</value>
   </data>
-</root>
+  <data name="StateShouldBeNullForRouteValueTransformers" xml:space="preserve">
+    <value>Transformer '{0}' was retrieved from dependency injection with a state value. State can only be specified when the dynamic route is mapped using MapDynamicControllerRoute's state argument together with transient lifetime transformer. Ensure that '{0}' doesn't set its own state and that the transformer is registered with a transient lifetime in dependency injection.</value>
+  </data>
+</root>

src/Mvc/Mvc.Core/src/Routing/DynamicControllerEndpointMatcherPolicy.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Core;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Matching;
 using Microsoft.Extensions.DependencyInjection;
@@ -97,13 +98,21 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                 // no realistic way this could happen.
                 var dynamicControllerMetadata = endpoint.Metadata.GetMetadata<DynamicControllerMetadata>();
                 var transformerMetadata = endpoint.Metadata.GetMetadata<DynamicControllerRouteValueTransformerMetadata>();
+
+                DynamicRouteValueTransformer transformer = null;
                 if (dynamicControllerMetadata != null)
                 {
                     dynamicValues = dynamicControllerMetadata.Values;
                 }
                 else if (transformerMetadata != null)
                 {
-                    var transformer = (DynamicRouteValueTransformer)httpContext.RequestServices.GetRequiredService(transformerMetadata.SelectorType);
+                    transformer = (DynamicRouteValueTransformer)httpContext.RequestServices.GetRequiredService(transformerMetadata.SelectorType);
+                    if (transformer.State != null)
+                    {
+                        throw new InvalidOperationException(Resources.FormatStateShouldBeNullForRouteValueTransformers(transformerMetadata.SelectorType.Name));
+                    }
+                    transformer.State = transformerMetadata.State;
+
                     dynamicValues = await transformer.TransformAsync(httpContext, originalValues);
                 }
                 else
@@ -146,6 +155,16 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                     }
                 }
 
+                if (transformer != null)
+                {
+                    endpoints = await transformer.FilterAsync(httpContext, values, endpoints);
+                    if (endpoints.Count == 0)
+                    {
+                        candidates.ReplaceEndpoint(i, null, null);
+                        continue;
+                    }
+                }
+
                 // Update the route values
                 candidates.ReplaceEndpoint(i, endpoint, values);
 

src/Mvc/Mvc.Core/src/Routing/DynamicControllerRouteValueTransformerMetadata.cs

@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 {
     internal class DynamicControllerRouteValueTransformerMetadata : IDynamicEndpointMetadata
     {
-        public DynamicControllerRouteValueTransformerMetadata(Type selectorType)
+        public DynamicControllerRouteValueTransformerMetadata(Type selectorType, object state)
         {
             if (selectorType == null)
             {
@@ -23,10 +23,13 @@ namespace Microsoft.AspNetCore.Mvc.Routing
             }
 
             SelectorType = selectorType;
+            State = state;
         }
 
         public bool IsDynamic => true;
 
         public Type SelectorType { get; }
+
+        public object State { get; }
     }
 }

src/Mvc/Mvc.Core/src/Routing/DynamicRouteValueTransformer.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
@@ -20,17 +21,40 @@ namespace Microsoft.AspNetCore.Mvc.Routing
     /// <para>
     /// The route values returned from a <see cref="TransformAsync(HttpContext, RouteValueDictionary)"/> implementation
     /// will be used to select an action based on matching of the route values. All actions that match the route values
-    /// will be considered as candidates, and may be further disambiguated by <see cref="IEndpointSelectorPolicy" />
+    /// will be considered as candidates, and may be further disambiguated by 
-    /// implementations such as <see cref="HttpMethodMatcherPolicy" />.
+    /// <see cref="FilterAsync(HttpContext, RouteValueDictionary, IReadOnlyList{Endpoint})" /> as well as 
+    /// <see cref="IEndpointSelectorPolicy" /> implementations such as <see cref="HttpMethodMatcherPolicy" />.
+    /// </para>
+    /// <para>
+    /// Operations on a <see cref="DynamicRouteValueTransformer" /> instance will be called for each dynamic endpoint
+    /// in the following sequence:
+    /// 
+    /// <list type="bullet">
+    ///   <item><description><see cref="State" /> is set</description></item>
+    ///   <item><description><see cref="TransformAsync(HttpContext, RouteValueDictionary)"/></description></item>
+    ///   <item><description><see cref="FilterAsync(HttpContext, RouteValueDictionary, IReadOnlyList{Endpoint})" /></description></item>
+    /// </list>
+    /// 
+    /// Implementations that are registered with the service collection as transient may safely use class
+    /// members to persist state across these operations.
     /// </para>
     /// <para>
     /// Implementations <see cref="DynamicRouteValueTransformer" /> should be registered with the service
     /// collection as type <see cref="DynamicRouteValueTransformer" />. Implementations can use any service
-    /// lifetime.
+    /// lifetime. Implementations that make use of <see cref="State" /> must be registered as transient.
     /// </para>
     /// </remarks>
     public abstract class DynamicRouteValueTransformer
     {
+        /// <summary>
+        /// Gets or sets a state value. An arbitrary value passed to the transformer from where it was registered.
+        /// </summary>
+        /// <remarks>
+        /// Implementations that make use of <see cref="State" /> must be registered as transient with the service
+        /// collection.
+        /// </remarks>
+        public object State { get; set; }
+
         /// <summary>
         /// Creates a set of transformed route values that will be used to select an action.
         /// </summary>
@@ -38,5 +62,32 @@ namespace Microsoft.AspNetCore.Mvc.Routing
         /// <param name="values">The route values associated with the current match. Implementations should not modify <paramref name="values"/>.</param>
         /// <returns>A task which asynchronously returns a set of route values.</returns>
         public abstract ValueTask<RouteValueDictionary> TransformAsync(HttpContext httpContext, RouteValueDictionary values);
+
+        /// <summary>
+        /// Filters the set of endpoints that were chosen as a result of lookup based on the route values returned by 
+        /// <see cref="TransformAsync(HttpContext, RouteValueDictionary)" />. 
+        /// </summary>
+        /// <param name="httpContext">The <see cref="HttpContext" /> associated with the current request.</param>
+        /// <param name="values">The route values returned from <see cref="TransformAsync(HttpContext, RouteValueDictionary)" />.</param>
+        /// <param name="endpoints">
+        /// The endpoints that were chosen as a result of lookup based on the route values returned by
+        /// <see cref="TransformAsync(HttpContext, RouteValueDictionary)" />.
+        /// </param>
+        /// <returns>Asynchronously returns a list of endpoints to apply to the matches collection.</returns>
+        /// <remarks>
+        /// <para>
+        /// Implementations of <see cref="FilterAsync(HttpContext, RouteValueDictionary, IReadOnlyList{Endpoint})" /> may further
+        /// refine the list of endpoints chosen based on route value matching by returning a new list of endpoints based on 
+        /// <paramref name="endpoints" />.
+        /// </para>
+        /// <para>
+        /// <see cref="FilterAsync(HttpContext, RouteValueDictionary, IReadOnlyList{Endpoint})" /> will not be called in the case
+        /// where zero endpoints were matched based on route values.
+        /// </para>
+        /// </remarks>
+        public virtual ValueTask<IReadOnlyList<Endpoint>> FilterAsync(HttpContext httpContext, RouteValueDictionary values, IReadOnlyList<Endpoint> endpoints)
+        {
+            return new ValueTask<IReadOnlyList<Endpoint>>(endpoints);
+        }
     }
 }

src/Mvc/Mvc.Core/test/Routing/DynamicControllerEndpointMatcherPolicyTest.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -58,7 +58,7 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                 _ => Task.CompletedTask,
                 new EndpointMetadataCollection(new object[]
                 {
-                    new DynamicControllerRouteValueTransformerMetadata(typeof(CustomTransformer)),
+                    new DynamicControllerRouteValueTransformerMetadata(typeof(CustomTransformer), State),
                 }),
                 "dynamic");
 
@@ -68,10 +68,11 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
             var services = new ServiceCollection();
             services.AddRouting();
-            services.AddScoped<CustomTransformer>(s =>
+            services.AddTransient<CustomTransformer>(s =>
             {
                 var transformer = new CustomTransformer();
-                transformer.Transform = (c, values) => Transform(c, values);
+                transformer.Transform = (c, values, state) => Transform(c, values, state);
+                transformer.Filter = (c, values, state, candidates) => Filter(c, values, state, candidates);
                 return transformer;
             });
             Services = services.BuildServiceProvider();
@@ -91,7 +92,11 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
         private IServiceProvider Services { get; }
 
-        private Func<HttpContext, RouteValueDictionary, ValueTask<RouteValueDictionary>> Transform { get; set; }
+        private Func<HttpContext, RouteValueDictionary, object, ValueTask<RouteValueDictionary>> Transform { get; set; }
+
+        private Func<HttpContext, RouteValueDictionary, object, IReadOnlyList<Endpoint>, ValueTask<IReadOnlyList<Endpoint>>> Filter { get; set; } = (_, __, ___, e) => new ValueTask<IReadOnlyList<Endpoint>>(e);
+
+        private object State { get; } = new object();
 
         [Fact]
         public async Task ApplyAsync_NoMatch()
@@ -106,7 +111,7 @@ namespace Microsoft.AspNetCore.Mvc.Routing
             var candidates = new CandidateSet(endpoints, values, scores);
             candidates.SetValidity(0, false);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 throw new InvalidOperationException();
             };
@@ -135,7 +140,7 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary());
             };
@@ -166,7 +171,7 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
                 {
@@ -200,6 +205,37 @@ namespace Microsoft.AspNetCore.Mvc.Routing
             Assert.True(candidates.IsValidCandidate(0));
         }
 
+        [Fact]
+        public async Task ApplyAsync_ThrowsForTransformerWithInvalidLifetime()
+        {
+            // Arrange
+            var policy = new DynamicControllerEndpointMatcherPolicy(Selector, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    controller = "Home",
+                    action = "Index",
+                    state
+                }));
+            };
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = new ServiceCollection().AddScoped(sp => new CustomTransformer { State = "Invalid" }).BuildServiceProvider(),
+            };
+
+            // Act & Assert
+            await Assert.ThrowsAsync<InvalidOperationException>(() => policy.ApplyAsync(httpContext, candidates));
+        }
+
         [Fact]
         public async Task ApplyAsync_HasMatchFindsEndpoint_WithRouteValues()
         {
@@ -212,12 +248,13 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
                 {
                     controller = "Home",
                     action = "Index",
+                    state
                 }));
             };
 
@@ -242,15 +279,164 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                 {
                     Assert.Equal("controller", kvp.Key);
                     Assert.Equal("Home", kvp.Value);
-                }, 
+                },
                 kvp =>
                 {
                     Assert.Equal("slug", kvp.Key);
                     Assert.Equal("test", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("state", kvp.Key);
+                    Assert.Same(State, kvp.Value);
                 });
             Assert.True(candidates.IsValidCandidate(0));
         }
 
+        [Fact]
+        public async Task ApplyAsync_CanDiscardFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicControllerEndpointMatcherPolicy(Selector, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    controller = "Home",
+                    action = "Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) =>
+            {
+                return new ValueTask<IReadOnlyList<Endpoint>>(Array.Empty<Endpoint>());
+            };
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.False(candidates.IsValidCandidate(0));
+        }
+
+        [Fact]
+        public async Task ApplyAsync_CanReplaceFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicControllerEndpointMatcherPolicy(Selector, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    controller = "Home",
+                    action = "Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) => new ValueTask<IReadOnlyList<Endpoint>>(new[]
+            {
+                new Endpoint((ctx) => Task.CompletedTask, new EndpointMetadataCollection(Array.Empty<object>()), "ReplacedEndpoint")
+            });
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.Collection(
+                candidates[0].Values.OrderBy(kvp => kvp.Key),
+                kvp =>
+                {
+                    Assert.Equal("action", kvp.Key);
+                    Assert.Equal("Index", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("controller", kvp.Key);
+                    Assert.Equal("Home", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("slug", kvp.Key);
+                    Assert.Equal("test", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("state", kvp.Key);
+                    Assert.Same(State, kvp.Value);
+                });
+            Assert.Equal("ReplacedEndpoint", candidates[0].Endpoint.DisplayName);
+            Assert.True(candidates.IsValidCandidate(0));
+        }
+
+        [Fact]
+        public async Task ApplyAsync_CanExpandTheListOfFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicControllerEndpointMatcherPolicy(Selector, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    controller = "Home",
+                    action = "Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) => new ValueTask<IReadOnlyList<Endpoint>>(new[]
+            {
+                ControllerEndpoints[1], ControllerEndpoints[2]
+            });
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.Equal(2, candidates.Count);
+            Assert.True(candidates.IsValidCandidate(0));
+            Assert.True(candidates.IsValidCandidate(1));
+            Assert.Same(ControllerEndpoints[1], candidates[0].Endpoint);
+            Assert.Same(ControllerEndpoints[2], candidates[1].Endpoint);
+        }
+
         private class TestDynamicControllerEndpointSelector : DynamicControllerEndpointSelector
         {
             public TestDynamicControllerEndpointSelector(EndpointDataSource dataSource)
@@ -261,11 +447,18 @@ namespace Microsoft.AspNetCore.Mvc.Routing
 
         private class CustomTransformer : DynamicRouteValueTransformer
         {
-            public Func<HttpContext, RouteValueDictionary, ValueTask<RouteValueDictionary>> Transform { get; set; }
+            public Func<HttpContext, RouteValueDictionary, object, ValueTask<RouteValueDictionary>> Transform { get; set; }
+
+            public Func<HttpContext, RouteValueDictionary, object, IReadOnlyList<Endpoint>, ValueTask<IReadOnlyList<Endpoint>>> Filter { get; set; }
 
             public override ValueTask<RouteValueDictionary> TransformAsync(HttpContext httpContext, RouteValueDictionary values)
             {
-                return Transform(httpContext, values);
+                return Transform(httpContext, values, State);
+            }
+
+            public override ValueTask<IReadOnlyList<Endpoint>> FilterAsync(HttpContext httpContext, RouteValueDictionary values, IReadOnlyList<Endpoint> endpoints)
+            {
+                return Filter(httpContext, values, State, endpoints);
             }
         }
     }

src/Mvc/Mvc.RazorPages/src/Builder/RazorPagesEndpointRouteBuilderExtensions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -299,6 +299,30 @@ namespace Microsoft.AspNetCore.Builder
         /// </remarks>
         public static void MapDynamicPageRoute<TTransformer>(this IEndpointRouteBuilder endpoints, string pattern)
             where TTransformer : DynamicRouteValueTransformer
+        {
+            MapDynamicPageRoute<TTransformer>(endpoints, pattern, state: null);
+        }
+
+        /// <summary>
+        /// Adds a specialized <see cref="RouteEndpoint"/> to the <see cref="IEndpointRouteBuilder"/> that will
+        /// attempt to select a page using the route values produced by <typeparamref name="TTransformer"/>.
+        /// </summary>
+        /// <param name="endpoints">The <see cref="IEndpointRouteBuilder"/> to add the route to.</param>
+        /// <param name="pattern">The URL pattern of the route.</param>
+        /// <param name="state">A state object to provide to the <typeparamref name="TTransformer" /> instance.</param>
+        /// <typeparam name="TTransformer">The type of a <see cref="DynamicRouteValueTransformer"/>.</typeparam>
+        /// <remarks>
+        /// <para>
+        /// This method allows the registration of a <see cref="RouteEndpoint"/> and <see cref="DynamicRouteValueTransformer"/>
+        /// that combine to dynamically select a page using custom logic.
+        /// </para>
+        /// <para>
+        /// The instance of <typeparamref name="TTransformer"/> will be retrieved from the dependency injection container.
+        /// Register <typeparamref name="TTransformer"/> with the desired service lifetime in <c>ConfigureServices</c>.
+        /// </para>
+        /// </remarks>
+        public static void MapDynamicPageRoute<TTransformer>(this IEndpointRouteBuilder endpoints, string pattern, object state)
+            where TTransformer : DynamicRouteValueTransformer
         {
             if (endpoints == null)
             {
@@ -316,14 +340,14 @@ namespace Microsoft.AspNetCore.Builder
             GetOrCreateDataSource(endpoints).CreateInertEndpoints = true;
 
             endpoints.Map(
-                pattern, 
+                pattern,
                 context =>
                 {
                     throw new InvalidOperationException("This endpoint is not expected to be executed directly.");
                 })
                 .Add(b =>
                 {
-                    b.Metadata.Add(new DynamicPageRouteValueTransformerMetadata(typeof(TTransformer)));
+                    b.Metadata.Add(new DynamicPageRouteValueTransformerMetadata(typeof(TTransformer), state));
                 });
         }
 

src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageEndpointMatcherPolicy.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -105,13 +105,19 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 // no realistic way this could happen.
                 var dynamicPageMetadata = endpoint.Metadata.GetMetadata<DynamicPageMetadata>();
                 var transformerMetadata = endpoint.Metadata.GetMetadata<DynamicPageRouteValueTransformerMetadata>();
+                DynamicRouteValueTransformer transformer = null;
                 if (dynamicPageMetadata != null)
                 {
                     dynamicValues = dynamicPageMetadata.Values;
                 }
                 else if (transformerMetadata != null)
                 {
-                    var transformer = (DynamicRouteValueTransformer)httpContext.RequestServices.GetRequiredService(transformerMetadata.SelectorType);
+                    transformer = (DynamicRouteValueTransformer)httpContext.RequestServices.GetRequiredService(transformerMetadata.SelectorType);
+                    if (transformer.State != null)
+                    {
+                        throw new InvalidOperationException(Resources.FormatStateShouldBeNullForRouteValueTransformers(transformerMetadata.SelectorType.Name));
+                    }
+                    transformer.State = transformerMetadata.State;
                     dynamicValues = await transformer.TransformAsync(httpContext, originalValues);
                 }
                 else
@@ -154,6 +160,16 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                     }
                 }
 
+                if (transformer != null)
+                {
+                    endpoints = await transformer.FilterAsync(httpContext, values, endpoints);
+                    if (endpoints.Count == 0)
+                    {
+                        candidates.ReplaceEndpoint(i, null, null);
+                        continue;
+                    }
+                }
+
                 // Update the route values
                 candidates.ReplaceEndpoint(i, endpoint, values);
 

src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageRouteValueTransformerMetadata.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -9,7 +9,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 {
     internal class DynamicPageRouteValueTransformerMetadata : IDynamicEndpointMetadata
     {
-        public DynamicPageRouteValueTransformerMetadata(Type selectorType)
+        public DynamicPageRouteValueTransformerMetadata(Type selectorType, object state)
         {
             if (selectorType == null)
             {
@@ -24,10 +24,13 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             }
 
             SelectorType = selectorType;
+            State = state;
         }
 
         public bool IsDynamic => true;
 
+        public object State { get; }
+
         public Type SelectorType { get; }
     }
 }

src/Mvc/Mvc.RazorPages/src/Resources.resx

@@ -153,4 +153,7 @@
   <data name="InvalidActionDescriptorModelType" xml:space="preserve">
     <value>The model type for '{0}' is of type '{1}' which is not assignable to its declared model type '{2}'.</value>
   </data>
-</root>
+  <data name="StateShouldBeNullForRouteValueTransformers" xml:space="preserve">
+    <value>Transformer '{0}' was retrieved from dependency injection with a state value. State can only be specified when the dynamic route is mapped using MapDynamicPageRoute's state argument together with transient lifetime transformer. Ensure that '{0}' doesn't set its own state and that the transformer is registered with a transient lifetime in dependency injection.</value>
+  </data>
+</root>

src/Mvc/Mvc.RazorPages/test/Infrastructure/DynamicPageEndpointMatcherPolicyTest.cs

@@ -1,14 +1,12 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
-using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Matching;
@@ -30,6 +28,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                     {
                         ["page"] = "/Index",
                     },
+                    DisplayName = "/Index",
                 },
                 new PageActionDescriptor()
                 {
@@ -37,6 +36,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                     {
                         ["page"] = "/About",
                     },
+                    DisplayName = "/About"
                 },
             };
 
@@ -50,7 +50,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 _ => Task.CompletedTask,
                 new EndpointMetadataCollection(new object[]
                 {
-                    new DynamicPageRouteValueTransformerMetadata(typeof(CustomTransformer)),
+                    new DynamicPageRouteValueTransformerMetadata(typeof(CustomTransformer), State),
                 }),
                 "dynamic");
 
@@ -60,24 +60,38 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             var services = new ServiceCollection();
             services.AddRouting();
-            services.AddScoped<CustomTransformer>(s =>
+            services.AddTransient<CustomTransformer>(s =>
             {
                 var transformer = new CustomTransformer();
-                transformer.Transform = (c, values) => Transform(c, values);
+                transformer.Transform = (c, values, state) => Transform(c, values, state);
+                transformer.Filter = (c, values, state, endpoints) => Filter(c, values, state, endpoints);
                 return transformer;
             });
             Services = services.BuildServiceProvider();
 
             Comparer = Services.GetRequiredService<EndpointMetadataComparer>();
 
-            LoadedEndpoint = new Endpoint(_ => Task.CompletedTask, EndpointMetadataCollection.Empty, "Loaded");
+            LoadedEndpoints = new[]
+            {
+                new Endpoint(_ => Task.CompletedTask, EndpointMetadataCollection.Empty, "Test1"),
+                new Endpoint(_ => Task.CompletedTask, EndpointMetadataCollection.Empty, "Test2"),
+                new Endpoint(_ => Task.CompletedTask, EndpointMetadataCollection.Empty, "ReplacedLoaded")
+            };
 
             var loader = new Mock<PageLoader>();
             loader
                 .Setup(l => l.LoadAsync(It.IsAny<PageActionDescriptor>()))
-                .Returns(Task.FromResult(new CompiledPageActionDescriptor() { Endpoint = LoadedEndpoint, }));
+                .Returns<PageActionDescriptor>(descriptor => Task.FromResult(new CompiledPageActionDescriptor
+                {
+                    Endpoint = descriptor.DisplayName switch
+                    {
+                        "/Index" => LoadedEndpoints[0],
+                        "/About" => LoadedEndpoints[1],
+                        "/ReplacedEndpoint" => LoadedEndpoints[2],
+                        _ => throw new InvalidOperationException($"Invalid endpoint '{descriptor.DisplayName}'.")
+                    }
+                }));
             Loader = loader.Object;
-            
         }
 
         private EndpointMetadataComparer Comparer { get; }
@@ -88,15 +102,19 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
         private Endpoint DynamicEndpoint { get; }
 
-        private Endpoint LoadedEndpoint { get; }
+        private Endpoint [] LoadedEndpoints { get; }
 
         private PageLoader Loader { get; }
 
         private DynamicPageEndpointSelector Selector { get; }
 
+        private object State { get; }
+
         private IServiceProvider Services { get; }
 
-        private Func<HttpContext, RouteValueDictionary, ValueTask<RouteValueDictionary>> Transform { get; set; }
+        private Func<HttpContext, RouteValueDictionary, object, ValueTask<RouteValueDictionary>> Transform { get; set; }
+
+        private Func<HttpContext, RouteValueDictionary, object, IReadOnlyList<Endpoint>, ValueTask<IReadOnlyList<Endpoint>>> Filter { get; set; } = (_, __, ___, e) => new ValueTask<IReadOnlyList<Endpoint>>(e);
 
         [Fact]
         public async Task ApplyAsync_NoMatch()
@@ -111,7 +129,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             var candidates = new CandidateSet(endpoints, values, scores);
             candidates.SetValidity(0, false);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 throw new InvalidOperationException();
             };
@@ -140,7 +158,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary());
             };
@@ -171,7 +189,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
                 {
@@ -188,7 +206,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             await policy.ApplyAsync(httpContext, candidates);
 
             // Assert
-            Assert.Same(LoadedEndpoint, candidates[0].Endpoint);
+            Assert.Same(LoadedEndpoints[0], candidates[0].Endpoint);
             Assert.Collection(
                 candidates[0].Values.OrderBy(kvp => kvp.Key),
                 kvp =>
@@ -211,11 +229,12 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             var candidates = new CandidateSet(endpoints, values, scores);
 
-            Transform = (c, values) =>
+            Transform = (c, values, state) =>
             {
                 return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
                 {
                     page = "/Index",
+                    state
                 }));
             };
 
@@ -228,7 +247,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             await policy.ApplyAsync(httpContext, candidates);
 
             // Assert
-            Assert.Same(LoadedEndpoint, candidates[0].Endpoint);
+            Assert.Same(LoadedEndpoints[0], candidates[0].Endpoint);
             Assert.Collection(
                 candidates[0].Values.OrderBy(kvp => kvp.Key),
                 kvp =>
@@ -240,10 +259,185 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 {
                     Assert.Equal("slug", kvp.Key);
                     Assert.Equal("test", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("state", kvp.Key);
+                    Assert.Same(State, kvp.Value);
                 });
             Assert.True(candidates.IsValidCandidate(0));
         }
 
+        [Fact]
+        public async Task ApplyAsync_Throws_ForTransformersWithInvalidLifetime()
+        {
+            // Arrange
+            var policy = new DynamicPageEndpointMatcherPolicy(Selector, Loader, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    page = "/Index",
+                    state
+                }));
+            };
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = new ServiceCollection().AddScoped(sp => new CustomTransformer() { State = "Invalid" }).BuildServiceProvider()
+            };
+
+            // Act & Assert
+            await Assert.ThrowsAsync<InvalidOperationException>(() => policy.ApplyAsync(httpContext, candidates));
+        }
+
+        [Fact]
+        public async Task ApplyAsync_CanDiscardFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicPageEndpointMatcherPolicy(Selector, Loader, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    page = "/Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) =>
+            {
+                return new ValueTask<IReadOnlyList<Endpoint>>(Array.Empty<Endpoint>());
+            };
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.False(candidates.IsValidCandidate(0));
+        }
+
+        [Fact]
+        public async Task ApplyAsync_CanReplaceFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicPageEndpointMatcherPolicy(Selector, Loader, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    page = "/Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) => new ValueTask<IReadOnlyList<Endpoint>>(new[]
+            {
+                new Endpoint((ctx) => Task.CompletedTask, new EndpointMetadataCollection(new PageActionDescriptor()
+                {
+                    DisplayName = "/ReplacedEndpoint",
+                }), "ReplacedEndpoint")
+            });
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.Equal(1, candidates.Count);
+            Assert.Collection(
+                candidates[0].Values.OrderBy(kvp => kvp.Key),
+                kvp =>
+                {
+                    Assert.Equal("page", kvp.Key);
+                    Assert.Equal("/Index", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("slug", kvp.Key);
+                    Assert.Equal("test", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("state", kvp.Key);
+                    Assert.Same(State, kvp.Value);
+                });
+            Assert.Equal("ReplacedLoaded", candidates[0].Endpoint.DisplayName);
+            Assert.True(candidates.IsValidCandidate(0));
+        }
+
+        [Fact]
+        public async Task ApplyAsync_CanExpandTheListOfFoundEndpoints()
+        {
+            // Arrange
+            var policy = new DynamicPageEndpointMatcherPolicy(Selector, Loader, Comparer);
+
+            var endpoints = new[] { DynamicEndpoint, };
+            var values = new RouteValueDictionary[] { new RouteValueDictionary(new { slug = "test", }), };
+            var scores = new[] { 0, };
+
+            var candidates = new CandidateSet(endpoints, values, scores);
+
+            Transform = (c, values, state) =>
+            {
+                return new ValueTask<RouteValueDictionary>(new RouteValueDictionary(new
+                {
+                    page = "/Index",
+                    state
+                }));
+            };
+
+            Filter = (c, values, state, endpoints) => new ValueTask<IReadOnlyList<Endpoint>>(new[]
+            {
+                PageEndpoints[0], PageEndpoints[1]
+            });
+
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = Services,
+            };
+
+            // Act
+            await policy.ApplyAsync(httpContext, candidates);
+
+            // Assert
+            Assert.Equal(2, candidates.Count);
+            Assert.True(candidates.IsValidCandidate(0));
+            Assert.True(candidates.IsValidCandidate(1));
+            Assert.Same(LoadedEndpoints[0], candidates[0].Endpoint);
+            Assert.Same(LoadedEndpoints[1], candidates[1].Endpoint);
+        }
+
         private class TestDynamicPageEndpointSelector : DynamicPageEndpointSelector
         {
             public TestDynamicPageEndpointSelector(EndpointDataSource dataSource)
@@ -254,11 +448,18 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
         private class CustomTransformer : DynamicRouteValueTransformer
         {
-            public Func<HttpContext, RouteValueDictionary, ValueTask<RouteValueDictionary>> Transform { get; set; }
+            public Func<HttpContext, RouteValueDictionary, object, ValueTask<RouteValueDictionary>> Transform { get; set; }
+
+            public Func<HttpContext, RouteValueDictionary, object, IReadOnlyList<Endpoint>, ValueTask<IReadOnlyList<Endpoint>>> Filter { get; set; }
+
+            public override ValueTask<IReadOnlyList<Endpoint>> FilterAsync(HttpContext httpContext, RouteValueDictionary values, IReadOnlyList<Endpoint> endpoints)
+            {
+                return Filter(httpContext, values, State, endpoints);
+            }
 
             public override ValueTask<RouteValueDictionary> TransformAsync(HttpContext httpContext, RouteValueDictionary values)
             {
-                return Transform(httpContext, values);
+                return Transform(httpContext, values, State);
             }
         }
     }

src/Mvc/test/Mvc.FunctionalTests/RoutingDynamicTest.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Linq;
@@ -59,7 +59,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
         public async Task DynamicController_CanSelectControllerInArea()
         {
             // Arrange
-            var url = "http://localhost/dynamic/area%3Dadmin,controller%3Ddynamic,action%3Dindex";
+            var url = "http://localhost/v1/dynamic/area%3Dadmin,controller%3Ddynamic,action%3Dindex";
             var request = new HttpRequestMessage(HttpMethod.Get, url);
 
             // Act
@@ -71,11 +71,25 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Equal("Hello from dynamic controller: /link_generation/dynamic/index", content);
         }
 
+        [Fact]
+        public async Task DynamicController_CanFilterResultsBasedOnState()
+        {
+            // Arrange
+            var url = "http://localhost/v2/dynamic/area%3Dadmin,controller%3Ddynamic,action%3Dindex";
+            var request = new HttpRequestMessage(HttpMethod.Get, url);
+
+            // Act
+            var response = await Client.SendAsync(request);
+
+            // Assert
+            Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+        }
+
         [Fact]
         public async Task DynamicController_CanSelectControllerInArea_WithActionConstraints()
         {
             // Arrange
-            var url = "http://localhost/dynamic/area%3Dadmin,controller%3Ddynamic,action%3Dindex";
+            var url = "http://localhost/v1/dynamic/area%3Dadmin,controller%3Ddynamic,action%3Dindex";
             var request = new HttpRequestMessage(HttpMethod.Post, url);
 
             // Act
@@ -91,7 +105,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
         public async Task DynamicPage_CanSelectPage()
         {
             // Arrange
-            var url = "http://localhost/dynamicpage/page%3D%2FDynamicPage";
+            var url = "http://localhost/v1/dynamicpage/page%3D%2FDynamicPage";
             var request = new HttpRequestMessage(HttpMethod.Get, url);
 
             // Act
@@ -103,6 +117,21 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Equal("Hello from dynamic page: /DynamicPage", content);
         }
 
+        [Fact]
+        public async Task DynamicPage_CanFilterBasedOnState()
+        {
+            // Arrange
+            var url = "http://localhost/v2/dynamicpage/page%3D%2FDynamicPage";
+            var request = new HttpRequestMessage(HttpMethod.Get, url);
+
+            // Act
+            var response = await Client.SendAsync(request);
+            var content = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+        }
+
         [Fact]
         public async Task AppWithDynamicRouteAndMapRazorPages_CanRouteToRazorPage()
         {

src/Mvc/test/WebSites/RoutingWebSite/DynamicVersion.cs

@@ -0,0 +1,10 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace RoutingWebSite
+{
+    public class DynamicVersion
+    {
+        public string Version { get; set; }
+    }
+}

src/Mvc/test/WebSites/RoutingWebSite/StartupForDynamic.cs

@@ -1,6 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
@@ -21,7 +23,7 @@ namespace RoutingWebSite
                 .AddNewtonsoftJson()
                 .SetCompatibilityVersion(CompatibilityVersion.Latest);
 
-            services.AddSingleton<Transformer>();
+            services.AddTransient<Transformer>();
 
             // Used by some controllers defined in this project.
             services.Configure<RouteOptions>(options => options.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer));
@@ -32,8 +34,10 @@ namespace RoutingWebSite
             app.UseRouting();
             app.UseEndpoints(endpoints =>
             {
-                endpoints.MapDynamicControllerRoute<Transformer>("dynamic/{**slug}");
+                endpoints.MapDynamicControllerRoute<Transformer>("v1/dynamic/{**slug}", new DynamicVersion { Version = "V1" });
-                endpoints.MapDynamicPageRoute<Transformer>("dynamicpage/{**slug}");
+                endpoints.MapDynamicControllerRoute<Transformer>("v2/dynamic/{**slug}", new DynamicVersion { Version = "V2" });
+                endpoints.MapDynamicPageRoute<Transformer>("v1/dynamicpage/{**slug}", new DynamicVersion { Version = "V1" });
+                endpoints.MapDynamicPageRoute<Transformer>("v2/dynamicpage/{**slug}", new DynamicVersion { Version = "V2" });
 
                 endpoints.MapControllerRoute("link", "link_generation/{controller}/{action}/{id?}");
 
@@ -59,8 +63,21 @@ namespace RoutingWebSite
                     results[split[0]] = split[1];
                 }
 
+                results["version"] = ((DynamicVersion)State).Version;
+
                 return new ValueTask<RouteValueDictionary>(results);
             }
+
+            public override ValueTask<IReadOnlyList<Endpoint>> FilterAsync(HttpContext httpContext, RouteValueDictionary values, IReadOnlyList<Endpoint> endpoints)
+            {
+                var version = ((DynamicVersion)State).Version;
+                if (version == "V2" && version == (string)values["version"])
+                {
+                    // For v1 routes this transformer will work fine, for v2 routes, it will filter them.
+                    return new ValueTask<IReadOnlyList<Endpoint>>(Array.Empty<Endpoint>());
+                }
+                return base.FilterAsync(httpContext, values, endpoints);
+            }
         }
     }
 }

src/Mvc/test/WebSites/RoutingWebSite/StartupForDynamicAndRazorPages.cs

@@ -20,7 +20,7 @@ namespace RoutingWebSite
                 .AddMvc()
                 .SetCompatibilityVersion(CompatibilityVersion.Latest);
 
-            services.AddSingleton<Transformer>();
+            services.AddTransient<Transformer>();
 
             // Used by some controllers defined in this project.
             services.Configure<RouteOptions>(options => options.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer));