Add PrepareShapeTable.

Lombiq.HelpfulLibraries.OrchardCore/DependencyInjection/ServiceCollectionExtensions.cs

@@ -5,6 +5,9 @@
 using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
+using OrchardCore.Admin;
+using OrchardCore.DisplayManagement.Descriptors;
+using OrchardCore.DisplayManagement.Theming;
 using OrchardCore.Modules;
 using System;
 using System.Threading.Tasks;
@@ -46,4 +49,24 @@ public static IServiceCollection AddInlineStartup(
         Func<IApplicationBuilder, IEndpointRouteBuilder, IServiceProvider, ValueTask>? configureAsync = null,
         int order = 0) =>
         services.AddSingleton<IStartup>(new InlineStartup(configureServices, configure, configureAsync, order));
+
+    /// <summary>
+    /// Registers an <see cref="IStartup"/> implementation that prepares the shape table for the current site and admin
+    /// themes. The <see cref="IStartup.Order"/> is the maximum possible value, ensuring that this will be executed
+    /// right before the site starts serving.
+    /// </summary>
+    public static IServiceCollection PrepareShapeTable(this IServiceCollection services) =>
+        services.AddInlineStartup(
+            configureAsync: async (_, _, serviceProvider) =>
+            {
+                var shapeTableManager = serviceProvider.GetRequiredService<IShapeTableManager>();
+
+                var siteTheme = await serviceProvider.GetRequiredService<IThemeManager>().GetThemeAsync();
+                var adminTheme = await serviceProvider.GetRequiredService<IAdminThemeService>().GetAdminThemeAsync();
+
+                await shapeTableManager.GetShapeTableAsync(themeId: null);
+                await shapeTableManager.GetShapeTableAsync(siteTheme.Id);
+                await shapeTableManager.GetShapeTableAsync(adminTheme.Id);
+            },
+            order: int.MaxValue);
 }