feat: support mapping optional routes automatically

src/Cnblogs.Architecture.Ddd.Cqrs.AspNetCore/CqrsRouteMapper.cs

@@ -1,10 +1,11 @@
 using System.Diagnostics.CodeAnalysis;
-
+using System.Reflection;
+using System.Text.RegularExpressions;
 using Cnblogs.Architecture.Ddd.Cqrs.Abstractions;
-
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.AspNetCore.Routing.Patterns;
 
 namespace Cnblogs.Architecture.Ddd.Cqrs.AspNetCore;
 
@@ -22,35 +23,34 @@ public static class CqrsRouteMapper
     /// </summary>
     /// <param name="app"><see cref="IApplicationBuilder"/></param>
     /// <param name="route">The route template for API.</param>
+    /// <param name="mapNullableRouteParameters">Multiple routes should be mapped when for nullable route parameters.</param>
+    /// <param name="nullRouteParameterPattern">Replace route parameter with given string to represent null.</param>
     /// <typeparam name="T">The type of the query.</typeparam>
     /// <returns></returns>
-    public static IEndpointConventionBuilder MapQuery<T>(
-        this IEndpointRouteBuilder app,
-        [StringSyntax("Route")] string route)
-    {
-        return app.MapQuery(route, ([AsParameters] T query) => query);
-    }
-
-    /// <summary>
-    ///     Map a command API, using different HTTP methods based on prefix. See example for details.
-    /// </summary>
-    /// <param name="app"><see cref="ApplicationBuilder"/></param>
-    /// <param name="route">The route template.</param>
-    /// <typeparam name="T">The type of the command.</typeparam>
     /// <example>
+    /// The following code:
     /// <code>
-    ///     app.MapCommand&lt;CreateItemCommand&gt;("/items"); // Starts with 'Create' or 'Add' - POST
-    ///     app.MapCommand&lt;UpdateItemCommand&gt;("/items/{id:int}") // Starts with 'Update' or 'Replace' - PUT
-    ///     app.MapCommand&lt;DeleteCommand&gt;("/items/{id:int}") // Starts with 'Delete' or 'Remove' - DELETE
-    ///     app.MapCommand&lt;ResetItemCommand&gt;("/items/{id:int}:reset) // Others - PUT
+    ///     app.MapQuery&lt;ItemQuery&gt;("apps/{appName}/instance/{instanceId}/roles", true);
+    /// </code>
+    /// would register following routes:
+    /// <code>
+    /// apps/-/instance/-/roles
+    /// apps/{appName}/instance/-/roles
+    /// apps/-/instance/{instanceId}/roles
+    /// apps/{appName}/instance/{instanceId}/roles
     /// </code>
     /// </example>
-    /// <returns></returns>
-    public static IEndpointConventionBuilder MapCommand<T>(
+    public static IEndpointConventionBuilder MapQuery<T>(
         this IEndpointRouteBuilder app,
-        [StringSyntax("Route")] string route)
+        [StringSyntax("Route")] string route,
+        bool mapNullableRouteParameters = false,
+        string nullRouteParameterPattern = "-")
     {
-        return app.MapCommand(route, ([AsParameters] T command) => command);
+        return app.MapQuery(
+            route,
+            ([AsParameters] T query) => query,
+            mapNullableRouteParameters,
+            nullRouteParameterPattern);
     }
 
     /// <summary>
@@ -59,11 +59,28 @@ public static IEndpointConventionBuilder MapCommand<T>(
     /// <param name="app"><see cref="ApplicationBuilder"/></param>
     /// <param name="route">The route template.</param>
     /// <param name="handler">The delegate that returns a <see cref="IQuery{TView}"/> instance.</param>
+    /// <param name="mapNullableRouteParameters">Multiple routes should be mapped when for nullable route parameters.</param>
+    /// <param name="nullRouteParameterPattern">Replace route parameter with given string to represent null.</param>
     /// <returns></returns>
+    /// <example>
+    /// The following code:
+    /// <code>
+    ///     app.MapQuery("apps/{appName}/instance/{instanceId}/roles", (string? appName, string? instanceId) => new ItemQuery(appName, instanceId), true);
+    /// </code>
+    /// would register following routes:
+    /// <code>
+    /// apps/-/instance/-/roles
+    /// apps/{appName}/instance/-/roles
+    /// apps/-/instance/{instanceId}/roles
+    /// apps/{appName}/instance/{instanceId}/roles
+    /// </code>
+    /// </example>
     public static IEndpointConventionBuilder MapQuery(
         this IEndpointRouteBuilder app,
         [StringSyntax("Route")] string route,
-        Delegate handler)
+        Delegate handler,
+        bool mapNullableRouteParameters = false,
+        string nullRouteParameterPattern = "-")
     {
         var isQuery = handler.Method.ReturnType.GetInterfaces().Where(x => x.IsGenericType)
             .Any(x => QueryTypes.Contains(x.GetGenericTypeDefinition()));
@@ -73,9 +90,69 @@ public static IEndpointConventionBuilder MapQuery(
                 "delegate does not return a query, please make sure it returns object that implement IQuery<> or IListQuery<> or interface that inherit from them");
         }
 
+        if (mapNullableRouteParameters == false)
+        {
+            return app.MapGet(route, handler).AddEndpointFilter<QueryEndpointHandler>();
+        }
+
+        if (string.IsNullOrWhiteSpace(nullRouteParameterPattern))
+        {
+            throw new ArgumentNullException(
+                nameof(nullRouteParameterPattern),
+                "argument must not be null or empty");
+        }
+
+        var parsedRoute = RoutePatternFactory.Parse(route);
+        var context = new NullabilityInfoContext();
+        var nullableRouteProperties = handler.Method.ReturnType.GetProperties()
+            .Where(
+                p => p.GetMethod != null
+                     && p.SetMethod != null
+                     && context.Create(p.GetMethod.ReturnParameter).ReadState == NullabilityState.Nullable)
+            .ToList();
+        var nullableRoutePattern = parsedRoute.Parameters
+            .Where(
+                x => nullableRouteProperties.Any(
+                    y => string.Equals(x.Name, y.Name, StringComparison.OrdinalIgnoreCase)))
+            .ToList();
+        var subsets = GetNotEmptySubsets(nullableRoutePattern);
+        foreach (var subset in subsets)
+        {
+            var newRoute = subset.Aggregate(
+                route,
+                (r, x) =>
+                {
+                    var regex = new Regex("{" + x.Name + "[^}]*?}", RegexOptions.IgnoreCase);
+                    return regex.Replace(r, nullRouteParameterPattern);
+                });
+            app.MapGet(newRoute, handler).AddEndpointFilter<QueryEndpointHandler>();
+        }
+
         return app.MapGet(route, handler).AddEndpointFilter<QueryEndpointHandler>();
     }
 
+    /// <summary>
+    ///     Map a command API, using different HTTP methods based on prefix. See example for details.
+    /// </summary>
+    /// <param name="app"><see cref="ApplicationBuilder"/></param>
+    /// <param name="route">The route template.</param>
+    /// <typeparam name="T">The type of the command.</typeparam>
+    /// <example>
+    /// <code>
+    ///     app.MapCommand&lt;CreateItemCommand&gt;("/items"); // Starts with 'Create' or 'Add' - POST
+    ///     app.MapCommand&lt;UpdateItemCommand&gt;("/items/{id:int}") // Starts with 'Update' or 'Replace' - PUT
+    ///     app.MapCommand&lt;DeleteCommand&gt;("/items/{id:int}") // Starts with 'Delete' or 'Remove' - DELETE
+    ///     app.MapCommand&lt;ResetItemCommand&gt;("/items/{id:int}:reset) // Others - PUT
+    /// </code>
+    /// </example>
+    /// <returns></returns>
+    public static IEndpointConventionBuilder MapCommand<T>(
+        this IEndpointRouteBuilder app,
+        [StringSyntax("Route")] string route)
+    {
+        return app.MapCommand(route, ([AsParameters] T command) => command);
+    }
+
     /// <summary>
     ///     Map a command API, using different method based on type name prefix.
     /// </summary>
@@ -174,4 +251,18 @@ private static void EnsureDelegateReturnTypeIsCommand(Delegate handler)
                 "handler does not return command, check if delegate returns type that implements ICommand<> or ICommand<,>");
         }
     }
+
+    private static List<T[]> GetNotEmptySubsets<T>(ICollection<T> items)
+    {
+        var subsetCount = 1 << items.Count;
+        var results = new List<T[]>(subsetCount);
+        for (var i = 1; i < subsetCount; i++)
+        {
+            var index = i;
+            var subset = items.Where((_, j) => (index & (1 << j)) > 0).ToArray();
+            results.Add(subset);
+        }
+
+        return results;
+    }
 }

test/Cnblogs.Architecture.IntegrationTestProject/Application/Queries/GetStringQuery.cs

@@ -2,4 +2,4 @@
 
 namespace Cnblogs.Architecture.IntegrationTestProject.Application.Queries;
 
-public record GetStringQuery : IQuery<string>;
+public record GetStringQuery(string? AppId = null, int? StringId = null) : IQuery<string>;

test/Cnblogs.Architecture.IntegrationTestProject/Program.cs

@@ -35,6 +35,7 @@
 
 var apis = app.NewVersionedApi();
 var v1 = apis.MapGroup("/api/v{version:apiVersion}").HasApiVersion(1);
+v1.MapQuery<GetStringQuery>("apps/{appId}/strings/{stringId:int}/value", true);
 v1.MapQuery<GetStringQuery>("strings/{id:int}");
 v1.MapQuery<ListStringsQuery>("strings");
 v1.MapCommand("strings", (CreatePayload payload) => new CreateCommand(payload.NeedError));

test/Cnblogs.Architecture.IntegrationTests/CqrsRouteMapperTests.cs

@@ -77,4 +77,23 @@ public async Task DeleteItem_SuccessAsync()
         // Assert
         response.Should().BeSuccessful();
     }
-}
+
+    [Fact]
+    public async Task GetItem_NullableRouteValue_SuccessAsync()
+    {
+        // Arrange
+        var builder = new WebApplicationFactory<Program>();
+
+        // Act
+        var responses = new List<HttpResponseMessage>
+        {
+            await builder.CreateClient().GetAsync("/api/v1/apps/-/strings/-/value"),
+            await builder.CreateClient().GetAsync("/api/v1/apps/-/strings/1/value"),
+            await builder.CreateClient().GetAsync("/api/v1/apps/someApp/strings/-/value"),
+            await builder.CreateClient().GetAsync("/api/v1/apps/someApp/strings/1/value")
+        };
+
+        // Assert
+        responses.Should().Match(x => x.All(y => y.IsSuccessStatusCode));
+    }
+}