Etag support.

src/Squidex/Areas/Api/Controllers/Apps/AppsController.cs

@@ -14,6 +14,7 @@ using Squidex.Areas.Api.Controllers.Apps.Models;
 using Squidex.Domain.Apps.Entities;
 using Squidex.Domain.Apps.Entities.Apps.Commands;
 using Squidex.Domain.Apps.Entities.Apps.Services;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.Commands;
 using Squidex.Infrastructure.Security;
 using Squidex.Pipeline;
@@ -62,6 +63,8 @@ namespace Squidex.Areas.Api.Controllers.Apps
 
             var response = entities.Select(a => AppDto.FromApp(a, subject, appPlansProvider)).ToList();
 
+            Response.Headers["Etag"] = string.Join(";", response.Select(x => $"{x.Id}{x.Version}")).Sha256Base64();
+
             return Ok(response);
         }
 

src/Squidex/Areas/Api/Controllers/Assets/Models/AssetDto.cs

@@ -12,10 +12,11 @@ using NodaTime;
 using Squidex.Domain.Apps.Entities.Assets;
 using Squidex.Infrastructure;
 using Squidex.Infrastructure.Reflection;
+using Squidex.Pipeline;
 
 namespace Squidex.Areas.Api.Controllers.Assets.Models
 {
-    public sealed class AssetDto
+    public sealed class AssetDto : IGenerateEtag
     {
         /// <summary>
         /// The id of the asset.
@@ -97,6 +98,11 @@ namespace Squidex.Areas.Api.Controllers.Assets.Models
         /// </summary>
         public long Version { get; set; }
 
+        public string GenerateETag()
+        {
+            return $"{Id}{Version}";
+        }
+
         public static AssetDto FromAsset(IAssetEntity asset)
         {
             return SimpleMapper.Map(asset, new AssetDto { FileType = asset.FileName.FileType() });

src/Squidex/Areas/Api/Controllers/Assets/Models/AssetsDto.cs

@@ -9,10 +9,11 @@ using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using Squidex.Domain.Apps.Entities.Assets;
 using Squidex.Infrastructure;
+using Squidex.Pipeline;
 
 namespace Squidex.Areas.Api.Controllers.Assets.Models
 {
-    public sealed class AssetsDto
+    public sealed class AssetsDto : IGenerateEtag
     {
         /// <summary>
         /// The assets.
@@ -25,6 +26,11 @@ namespace Squidex.Areas.Api.Controllers.Assets.Models
         /// </summary>
         public long Total { get; set; }
 
+        public string GenerateETag()
+        {
+            return string.Join(";", Items?.Select(x => x.GenerateETag()) ?? Enumerable.Empty<string>()).Sha256Base64();
+        }
+
         public static AssetsDto FromAssets(IResultList<IAssetEntity> assets)
         {
             return new AssetsDto { Total = assets.Total, Items = assets.Select(AssetDto.FromAsset).ToArray() };

src/Squidex/Areas/Api/Controllers/Contents/Models/ContentDto.cs

@@ -16,10 +16,11 @@ using Squidex.Domain.Apps.Entities.Contents.Commands;
 using Squidex.Infrastructure;
 using Squidex.Infrastructure.Commands;
 using Squidex.Infrastructure.Reflection;
+using Squidex.Pipeline;
 
 namespace Squidex.Areas.Api.Controllers.Contents.Models
 {
-    public sealed class ContentDto
+    public sealed class ContentDto : IGenerateEtag
     {
         /// <summary>
         /// The if of the content item.
@@ -79,6 +80,11 @@ namespace Squidex.Areas.Api.Controllers.Contents.Models
         /// </summary>
         public long Version { get; set; }
 
+        public string GenerateETag()
+        {
+            return $"{Id}{Version}";
+        }
+
         public static ContentDto FromCommand(CreateContent command, EntityCreatedResult<NamedContentData> result)
         {
             var now = SystemClock.Instance.GetCurrentInstant();

src/Squidex/Areas/Api/Controllers/Contents/Models/ContentsDto.cs

@@ -5,9 +5,13 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
+using System.Linq;
+using Squidex.Infrastructure;
+using Squidex.Pipeline;
+
 namespace Squidex.Areas.Api.Controllers.Contents.Models
 {
-    public sealed class ContentsDto
+    public sealed class ContentsDto : IGenerateEtag
     {
         /// <summary>
         /// The total number of content items.
@@ -18,5 +22,10 @@ namespace Squidex.Areas.Api.Controllers.Contents.Models
         /// The content items.
         /// </summary>
         public ContentDto[] Items { get; set; }
+
+        public string GenerateETag()
+        {
+            return string.Join(";", Items?.Select(x => x.GenerateETag()) ?? Enumerable.Empty<string>()).Sha256Base64();
+        }
     }
 }

src/Squidex/Areas/Frontend/Middlewares/WebpackMiddleware.cs

@@ -27,18 +27,18 @@ namespace Squidex.Areas.Frontend.Middlewares
 
         public async Task Invoke(HttpContext context)
         {
-            var buffer = new MemoryStream();
+            var responseBuffer = new MemoryStream();
-            var body = context.Response.Body;
+            var responseBody = context.Response.Body;
 
-            context.Response.Body = buffer;
+            context.Response.Body = responseBuffer;
 
             await next(context);
 
-            buffer.Seek(0, SeekOrigin.Begin);
+            responseBuffer.Seek(0, SeekOrigin.Begin);
 
             if (context.Response.StatusCode == 200 && IsIndex(context) && IsHtml(context))
             {
-                using (var reader = new StreamReader(buffer))
+                using (var reader = new StreamReader(responseBuffer))
                 {
                     var response = await reader.ReadToEndAsync();
 
@@ -56,17 +56,17 @@ namespace Squidex.Areas.Frontend.Middlewares
 
                             context.Response.Headers["Content-Length"] = memoryStream.Length.ToString();
 
-                            await memoryStream.CopyToAsync(body);
+                            await memoryStream.CopyToAsync(responseBody);
                         }
                     }
                 }
             }
             else if (context.Response.StatusCode != 304)
             {
-                await buffer.CopyToAsync(body);
+                await responseBuffer.CopyToAsync(responseBody);
             }
 
-            context.Response.Body = body;
+            context.Response.Body = responseBody;
         }
 
         private static string InjectStyles(string response)

src/Squidex/Config/Web/WebServices.cs

@@ -33,7 +33,11 @@ namespace Squidex.Config.Web
             services.AddSingletonAs<RequestLogPerformanceMiddleware>()
                 .AsSelf();
 
-            services.AddMvc().AddMySerializers();
+            services.AddMvc(options =>
+            {
+                options.Filters.Add<ETagFilter>();
+            }).AddMySerializers();
+
             services.AddCors();
             services.AddRouting();
         }

src/Squidex/Pipeline/ETagFilter.cs

@@ -0,0 +1,44 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+
+namespace Squidex.Pipeline
+{
+    public sealed class ETagFilter : IAsyncActionFilter
+    {
+        public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
+        {
+            var resultContext = await next();
+
+            var httpContext = context.HttpContext;
+
+            if (!httpContext.Response.Headers.TryGetValue("Etag", out _) && resultContext.Result is ObjectResult obj && obj.Value is IGenerateEtag g)
+            {
+                var calculatedEtag = g.GenerateETag();
+
+                if (!string.IsNullOrWhiteSpace(calculatedEtag))
+                {
+                    httpContext.Response.Headers.Add("Etag", calculatedEtag);
+                }
+            }
+
+            if (httpContext.Request.Method == "GET" &&
+                httpContext.Request.Headers.TryGetValue("If-None-Match", out var noneMatch) &&
+                httpContext.Response.StatusCode == 200 &&
+                httpContext.Response.Headers.TryGetValue("Etag", out var etag) &&
+                !string.IsNullOrWhiteSpace(noneMatch) &&
+                !string.IsNullOrWhiteSpace(etag) &&
+                string.Equals(etag, noneMatch, System.StringComparison.Ordinal))
+            {
+                resultContext.Result = new StatusCodeResult(304);
+            }
+        }
+    }
+}

src/Squidex/Pipeline/IGenerateEtag.cs

@@ -0,0 +1,14 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+namespace Squidex.Pipeline
+{
+    public interface IGenerateEtag
+    {
+        string GenerateETag();
+    }
+}