Add rendering event (#464)

.github/workflows/build.yml

@@ -23,23 +23,17 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Setup .NET 2.1
-      uses: actions/setup-dotnet@v1
-      with:
-        dotnet-version: 2.1.*
-    - name: Setup .NET 3.1
-      uses: actions/setup-dotnet@v1
-      with:
-        dotnet-version: 3.1.*
-    - name: Setup .NET 5.0
-      uses: actions/setup-dotnet@v1
-      with:
-        dotnet-version: 5.0.*
-    - name: Setup .NET 6.0
+
+    - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 6.0.*
+        dotnet-version: | 
+          3.1.x
+          5.0.x
+          6.0.x
+          
     - name: Test
       run: dotnet test --configuration Release
+
     - name: Test - Compiled
       run: dotnet test --configuration Release /p:Compiled=true

Fluid.MvcViewEngine/FluidMvcViewOptions.cs

@@ -1,9 +1,16 @@
 using Fluid.ViewEngine;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using System.Threading.Tasks;
 
 namespace Fluid.MvcViewEngine
 {
     public class FluidMvcViewOptions : FluidViewEngineOptions
     {
-        // Placeholder for future options specific to the MVC view engine
+        public delegate ValueTask RenderingMvcViewDelegate(string path, ViewContext viewContext, TemplateContext context);
+
+        /// <summary>
+        /// Gets or sets the delegate to execute when a view is rendered.
+        /// </summary>
+        public new RenderingMvcViewDelegate RenderingViewAsync { get; set; }
     }
 }

Fluid.MvcViewEngine/FluidRendering.cs

@@ -1,6 +1,7 @@
 using Fluid.ViewEngine;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.Extensions.Options;
 using System.IO;
@@ -32,14 +33,19 @@ public FluidRendering(
         }
 
         private readonly IWebHostEnvironment _hostingEnvironment;
-        private readonly FluidViewEngineOptions _options;
+        private readonly FluidMvcViewOptions _options;
 
-        public async Task RenderAsync(TextWriter writer, string path, object model, ViewDataDictionary viewData, ModelStateDictionary modelState)
+        public async Task RenderAsync(TextWriter writer, string path, ViewContext viewContext)
         {
             var context = new TemplateContext(_options.TemplateOptions);
-            context.SetValue("ViewData", viewData);
-            context.SetValue("ModelState", modelState);
-            context.SetValue("Model", model);
+            context.SetValue("ViewData", viewContext.ViewData);
+            context.SetValue("ModelState", viewContext.ModelState);
+            context.SetValue("Model", viewContext.ViewData.Model);
+
+            if (_options.RenderingViewAsync != null)
+            {
+                await _options.RenderingViewAsync.Invoke(path, viewContext, context);
+            }
 
             await _fluidViewRenderer.RenderViewAsync(writer, path, context);
         }

Fluid.MvcViewEngine/FluidTagHelper.cs

@@ -1,5 +1,7 @@
 using System.IO;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 
 namespace Fluid.MvcViewEngine
@@ -14,6 +16,10 @@ public FluidTagHelper(FluidRendering fluidRendering)
             _fluidRendering = fluidRendering;
         }
 
+        [HtmlAttributeNotBound]
+        [ViewContext]
+        public ViewContext ViewContext { get; set; }
+
         [HtmlAttributeName("model")]
         public object Model { get; set; }
 
@@ -31,7 +37,7 @@ static async Task Awaited(TagHelperOutput o, StringWriter sw, Task t)
 
             using (var sw = new StringWriter())
             {
-                var task = _fluidRendering.RenderAsync(sw, View, Model, null, null);
+                var task = _fluidRendering.RenderAsync(sw, View, ViewContext);
 
                 if (task.IsCompletedSuccessfully)
                 {

Fluid.MvcViewEngine/FluidView.cs

@@ -25,7 +25,7 @@ public string Path
 
         public async Task RenderAsync(ViewContext context)
         {
-            await _fluidRendering.RenderAsync(context.Writer, Path, context.ViewData.Model, context.ViewData, context.ModelState);
+            await _fluidRendering.RenderAsync(context.Writer, Path, context);
         }
     }
 }

Fluid.Tests/MvcViewEngine/ViewEngineTests.cs

@@ -225,10 +225,25 @@ public async Task ShouldNotIncludeViewStartInLayout()
             var sw = new StringWriter();
             await _renderer.RenderViewAsync(sw, "Index.liquid", new TemplateContext());
             await sw.FlushAsync();
-
             Assert.Equal("[Layout][ViewStart][View]", sw.ToString());
         }
 
+        [Fact]
+        public async Task ShouldInvokeRenderingViewAsync()
+        {
+            _options.RenderingViewAsync = (view, context) => { context.SetValue("custom", "hello"); return default; };
+
+            _mockFileProvider.Add("Views/Index.liquid", "{{ custom }}");
+
+            var sw = new StringWriter();
+            await _renderer.RenderViewAsync(sw, "Index.liquid", new TemplateContext());
+            await sw.FlushAsync();
+
+            _options.RenderingViewAsync = null;
+
+            Assert.Equal("hello", sw.ToString());
+        }
+
         [Fact]
         public async Task ShouldApplyViewStartLayoutsRecursively()
         {

Fluid.ViewEngine/FluidViewEngineOptions.cs

@@ -1,6 +1,8 @@
 using Microsoft.Extensions.FileProviders;
+using System;
 using System.Collections.Generic;
 using System.Text.Encodings.Web;
+using System.Threading.Tasks;
 
 namespace Fluid.ViewEngine
 {
@@ -62,5 +64,15 @@ public class FluidViewEngineOptions
         /// Gets or sets whether files should be reloaded automatically when changed. Default is <code>true</code>;
         /// </summary>
         public bool TrackFileChanges { get; set; } = true;
+
+        /// <summary>
+        /// <para>Represents the method that will handle the view rendering event.</para>
+        /// </summary>
+        public delegate ValueTask RenderingViewDelegate(string path, TemplateContext context);
+
+        /// <summary>
+        /// Gets or sets the delegate to execute when a view is rendered.
+        /// </summary>
+        public RenderingViewDelegate RenderingViewAsync { get; set; }
     }
 }

Fluid.ViewEngine/FluidViewRenderer.cs

@@ -43,6 +43,11 @@ public virtual async Task RenderViewAsync(TextWriter writer, string relativePath
 
             var template = await GetFluidTemplateAsync(relativePath, _fluidViewEngineOptions.ViewsFileProvider, true);
 
+            if (_fluidViewEngineOptions.RenderingViewAsync != null)
+            {
+                await _fluidViewEngineOptions.RenderingViewAsync.Invoke(relativePath, context);
+            }
+
             // The body is rendered and buffered before the Layout since it can contain fragments 
             // that need to be rendered as part of the Layout.
             // Also the body or its _ViewStarts might contain a Layout tag.
@@ -73,6 +78,11 @@ public virtual async Task RenderPartialAsync(TextWriter writer, string relativeP
             // Substitute View Path
             context.AmbientValues[Constants.ViewPathIndex] = relativePath;
 
+            if (_fluidViewEngineOptions.RenderingViewAsync != null)
+            {
+                await _fluidViewEngineOptions.RenderingViewAsync.Invoke(relativePath, context);
+            }
+
             var template = await GetFluidTemplateAsync(relativePath, _fluidViewEngineOptions.PartialsFileProvider, false);
 
             await template.RenderAsync(writer, _fluidViewEngineOptions.TextEncoder, context);