c# - net - razor语法




在.NET Core中在MVC之外使用Razor (4)

我想将Razor用作我在.NET Core中编写的.NET控制台应用程序中的模板引擎。

我遇到的独立Razor引擎(RazorEngine,RazorTemplates)都需要完整的.NET。 我正在寻找一种适用于.NET Core的解决方案。


我花了几天时间摆弄剃须刀灯,但是它有很多缺陷,例如没有html helper(@ Html。*)或url helper,以及其他一些怪癖。

这是一种封装在mvc应用程序外部使用的解决方案。 它确实需要对aspnet core和mvc的程序包引用,但是它们很容易添加到服务或控制台应用程序中。 无需控制器或Web服务器。 RenderToStringAsync是用于将视图呈现为字符串的调用方法。

好处是您可以像在.net核心Web项目中一样编写视图。 您可以使用相同的@Html以及其他辅助函数和方法。

您可以使用自己的自定义提供程序在razor视图选项设置中替换或添加到物理文件提供程序,以从数据库,Web服务调用等加载视图。在Windows和Linux上使用.net core 2.2测试。

请注意,您的.csproj文件必须将其作为第一行:

<Project Sdk="Microsoft.NET.Sdk.Web">
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Dynamic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Internal;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.ObjectPool;

namespace RazorRendererNamespace
{
    /// <summary>
    /// Renders razor pages with the absolute minimum setup of MVC, easy to use in console application, does not require any other classes or setup.
    /// </summary>
    public class RazorRenderer : ILoggerFactory, ILogger
    {
        private class ViewRenderService : IDisposable, ITempDataProvider, IServiceProvider
        {
            private static readonly System.Net.IPAddress localIPAddress = System.Net.IPAddress.Parse("127.0.0.1");

            private readonly Dictionary<string, object> tempData = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
            private readonly IRazorViewEngine _viewEngine;
            private readonly ITempDataProvider _tempDataProvider;
            private readonly IServiceProvider _serviceProvider;
            private readonly IHttpContextAccessor _httpContextAccessor;

            public ViewRenderService(IRazorViewEngine viewEngine,
                IHttpContextAccessor httpContextAccessor,
                ITempDataProvider tempDataProvider,
                IServiceProvider serviceProvider)
            {
                _viewEngine = viewEngine;
                _httpContextAccessor = httpContextAccessor;
                _tempDataProvider = tempDataProvider ?? this;
                _serviceProvider = serviceProvider ?? this;
            }

            public void Dispose()
            {

            }

            public async Task<string> RenderToStringAsync<TModel>(string viewName, TModel model, ExpandoObject viewBag = null, bool isMainPage = false)
            {
                HttpContext httpContext;
                if (_httpContextAccessor?.HttpContext != null)
                {
                    httpContext = _httpContextAccessor.HttpContext;
                }
                else
                {
                    DefaultHttpContext defaultContext = new DefaultHttpContext { RequestServices = _serviceProvider };
                    defaultContext.Connection.RemoteIpAddress = localIPAddress;
                    httpContext = defaultContext;
                }
                var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
                using (var sw = new StringWriter())
                {
                    var viewResult = _viewEngine.FindView(actionContext, viewName, isMainPage);

                    if (viewResult.View == null)
                    {
                        viewResult = _viewEngine.GetView("~/", viewName, isMainPage);
                    }

                    if (viewResult.View == null)
                    {
                        return null;
                    }

                    var viewDictionary = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary())
                    {
                        Model = model
                    };
                    if (viewBag != null)
                    {
                        foreach (KeyValuePair<string, object> kv in (viewBag as IDictionary<string, object>))
                        {
                            viewDictionary.Add(kv.Key, kv.Value);
                        }
                    }
                    var viewContext = new ViewContext(
                        actionContext,
                        viewResult.View,
                        viewDictionary,
                        new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
                        sw,
                        new HtmlHelperOptions()
                    );

                    await viewResult.View.RenderAsync(viewContext);
                    return sw.ToString();
                }
            }

            object IServiceProvider.GetService(Type serviceType)
            {
                return null;
            }

            IDictionary<string, object> ITempDataProvider.LoadTempData(HttpContext context)
            {
                return tempData;
            }

            void ITempDataProvider.SaveTempData(HttpContext context, IDictionary<string, object> values)
            {
            }
        }

        private readonly string rootPath;
        private readonly ServiceCollection services;
        private readonly ServiceProvider serviceProvider;
        private readonly ViewRenderService viewRenderer;

        public RazorRenderer(string rootPath)
        {
            this.rootPath = rootPath;
            services = new ServiceCollection();
            ConfigureDefaultServices(services);
            serviceProvider = services.BuildServiceProvider();
            viewRenderer = new ViewRenderService(serviceProvider.GetRequiredService<IRazorViewEngine>(), null, null, serviceProvider);
        }

        private void ConfigureDefaultServices(IServiceCollection services)
        {
            var environment = new HostingEnvironment
            {
                WebRootFileProvider = new PhysicalFileProvider(rootPath),
                ApplicationName = typeof(RazorRenderer).Assembly.GetName().Name,
                ContentRootPath = rootPath,
                WebRootPath = rootPath,
                EnvironmentName = "DEVELOPMENT",
                ContentRootFileProvider = new PhysicalFileProvider(rootPath)
            };
            services.AddSingleton<IHostingEnvironment>(environment);
            services.Configure<RazorViewEngineOptions>(options =>
            {
                options.FileProviders.Clear();
                options.FileProviders.Add(new PhysicalFileProvider(rootPath));
            });
            services.AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>();
            services.AddSingleton<ILoggerFactory>(this);
            var diagnosticSource = new DiagnosticListener(environment.ApplicationName);
            services.AddSingleton<DiagnosticSource>(diagnosticSource);
            services.AddMvc();
        }

        public void Dispose()
        {
        }

        public Task<string> RenderToStringAsync<TModel>(string viewName, TModel model, ExpandoObject viewBag = null, bool isMainPage = false)
        {
            return viewRenderer.RenderToStringAsync(viewName, model, viewBag, isMainPage);
        }

        void ILoggerFactory.AddProvider(ILoggerProvider provider)
        {

        }

        IDisposable ILogger.BeginScope<TState>(TState state)
        {
            throw new NotImplementedException();
        }

        ILogger ILoggerFactory.CreateLogger(string categoryName)
        {
            return this;
        }

        bool ILogger.IsEnabled(Microsoft.Extensions.Logging.LogLevel logLevel)
        {
            return false;
        }

        void ILogger.Log<TState>(Microsoft.Extensions.Logging.LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
        {
        }
    }
}

最近,我创建了一个名为 RazorLight 的库。

它没有多余的依赖性,例如ASP.NET MVC部件,可以在控制台应用程序中使用。 目前,它仅支持.NET Core(NetStandard1.6)-但这正是您所需要的。

这是一个简短的示例:

IRazorLightEngine engine = EngineFactory.CreatePhysical("Path-to-your-views");

// Files and strong models
string resultFromFile = engine.Parse("Test.cshtml", new Model("SomeData")); 

// Strings and anonymous models
string stringResult = engine.ParseString("Hello @Model.Name", new { Name = "John" }); 

这是一个类,可让Nate的答案在ASP.NET Core 2.0项目中充当范围服务。

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;

namespace YourNamespace.Services
{
    public class ViewRender : IViewRender
    {
        private readonly IRazorViewEngine _viewEngine;
        private readonly ITempDataProvider _tempDataProvider;
        private readonly IServiceProvider _serviceProvider;

        public ViewRender(
            IRazorViewEngine viewEngine,
            ITempDataProvider tempDataProvider,
            IServiceProvider serviceProvider)
        {
            _viewEngine = viewEngine;
            _tempDataProvider = tempDataProvider;
            _serviceProvider = serviceProvider;
        }

        public async Task<string> RenderAsync(string name)
        {
            return await RenderAsync<object>(name, null);
        }

        public async Task<string> RenderAsync<TModel>(string name, TModel model)
        {
            var actionContext = GetActionContext();

            var viewEngineResult = _viewEngine.FindView(actionContext, name, false);

            if (!viewEngineResult.Success)
            {
                throw new InvalidOperationException(string.Format("Couldn't find view '{0}'", name));
            }

            var view = viewEngineResult.View;

            using (var output = new StringWriter())
            {
                var viewContext = new ViewContext(
                    actionContext,
                    view,
                    new ViewDataDictionary<TModel>(
                        metadataProvider: new EmptyModelMetadataProvider(),
                        modelState: new ModelStateDictionary())
                    {
                        Model = model
                    },
                    new TempDataDictionary(
                        actionContext.HttpContext,
                        _tempDataProvider),
                    output,
                    new HtmlHelperOptions());

                await view.RenderAsync(viewContext);

                return output.ToString();
            }
        }

        private ActionContext GetActionContext()
        {
            var httpContext = new DefaultHttpContext {RequestServices = _serviceProvider};
            return new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
        }
    }

    public interface IViewRender
    {
        Task<string> RenderAsync(string name);

        Task<string> RenderAsync<TModel>(string name, TModel model);
    }
}

在Startup.cs中

public void ConfigureServices(IServiceCollection services)
{
     services.AddScoped<IViewRender, ViewRender>();
}

在控制器中

public class VenuesController : Controller
{
    private readonly IViewRender _viewRender;

    public VenuesController(IViewRender viewRender)
    {
        _viewRender = viewRender;
    }

    public async Task<IActionResult> Edit()
    {
        string html = await _viewRender.RenderAsync("Emails/VenuePublished", venue.Name);
        return Ok();
    }
}

aspnet/Entropy/samples/Mvc.RenderViewToString 有一个.NET Core 1.0的工作示例。 由于这可能会改变或消失,因此我将在这里详细说明我在自己的应用程序中使用的方法。

Tl; dr -Razor在MVC之外效果很好! 尽管我将在下面演示一个简单的示例,但是这种方法可以处理更复杂的渲染方案,例如局部视图,以及将对象注入视图。

核心服务如下所示:

RazorViewToStringRenderer.cs

using System;
using System.IO;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;

namespace RenderRazorToString
{
    public class RazorViewToStringRenderer
    {
        private readonly IRazorViewEngine _viewEngine;
        private readonly ITempDataProvider _tempDataProvider;
        private readonly IServiceProvider _serviceProvider;

        public RazorViewToStringRenderer(
            IRazorViewEngine viewEngine,
            ITempDataProvider tempDataProvider,
            IServiceProvider serviceProvider)
        {
            _viewEngine = viewEngine;
            _tempDataProvider = tempDataProvider;
            _serviceProvider = serviceProvider;
        }

        public async Task<string> RenderViewToString<TModel>(string name, TModel model)
        {
            var actionContext = GetActionContext();

            var viewEngineResult = _viewEngine.FindView(actionContext, name, false);

            if (!viewEngineResult.Success)
            {
                throw new InvalidOperationException(string.Format("Couldn't find view '{0}'", name));
            }

            var view = viewEngineResult.View;

            using (var output = new StringWriter())
            {
                var viewContext = new ViewContext(
                    actionContext,
                    view,
                    new ViewDataDictionary<TModel>(
                        metadataProvider: new EmptyModelMetadataProvider(),
                        modelState: new ModelStateDictionary())
                    {
                        Model = model
                    },
                    new TempDataDictionary(
                        actionContext.HttpContext,
                        _tempDataProvider),
                    output,
                    new HtmlHelperOptions());

                await view.RenderAsync(viewContext);

                return output.ToString();
            }
        }

        private ActionContext GetActionContext()
        {
            var httpContext = new DefaultHttpContext
            {
                RequestServices = _serviceProvider
            };

            return new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
        }
    }
}

一个简单的测试控制台应用程序只需初始化服务(以及一些支持服务),然后调用它:

Program.cs中

using System;
using System.Diagnostics;
using System.IO;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Internal;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.ObjectPool;
using Microsoft.Extensions.PlatformAbstractions;

namespace RenderRazorToString
{
    public class Program
    {
        public static void Main()
        {
            // Initialize the necessary services
            var services = new ServiceCollection();
            ConfigureDefaultServices(services);
            var provider = services.BuildServiceProvider();

            var renderer = provider.GetRequiredService<RazorViewToStringRenderer>();

            // Build a model and render a view
            var model = new EmailViewModel
            {
                UserName = "User",
                SenderName = "Sender"
            };
            var emailContent = renderer.RenderViewToString("EmailTemplate", model).GetAwaiter().GetResult();

            Console.WriteLine(emailContent);
            Console.ReadLine();
        }

        private static void ConfigureDefaultServices(IServiceCollection services)
        {
            var applicationEnvironment = PlatformServices.Default.Application;
            services.AddSingleton(applicationEnvironment);

            var appDirectory = Directory.GetCurrentDirectory();

            var environment = new HostingEnvironment
            {
                WebRootFileProvider = new PhysicalFileProvider(appDirectory),
                ApplicationName = "RenderRazorToString"
            };
            services.AddSingleton<IHostingEnvironment>(environment);

            services.Configure<RazorViewEngineOptions>(options =>
            {
                options.FileProviders.Clear();
                options.FileProviders.Add(new PhysicalFileProvider(appDirectory));
            });

            services.AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>();

            var diagnosticSource = new DiagnosticListener("Microsoft.AspNetCore");
            services.AddSingleton<DiagnosticSource>(diagnosticSource);

            services.AddLogging();
            services.AddMvc();
            services.AddSingleton<RazorViewToStringRenderer>();
        }
    }
}

假设您有一个视图模型类:

EmailViewModel.cs

namespace RenderRazorToString
{
    public class EmailViewModel
    {
        public string UserName { get; set; }

        public string SenderName { get; set; }
    }
}

以及布局和查看文件:

查看/ _Layout.cshtml

<!DOCTYPE html>

<html>
<body>
    <div>
        @RenderBody()
    </div>
    <footer>
Thanks,<br />
@Model.SenderName
    </footer>
</body>
</html>

查看/ EmailTemplate.cshtml

@model RenderRazorToString.EmailViewModel
@{ 
    Layout = "_EmailLayout";
}

Hello @Model.UserName,

<p>
    This is a generic email about something.<br />
    <br />
</p>




.net-core