Asp.net Core中的@Html.Action
在哪里?我可以看到@Html.ActionLink
但不像以前那样直接调用Action。
它被ViewComponents取代了吗?
是的,ViewComponents将是这样做的新方式,但它们与@Html.Action
之前的做法并不完全相同...例如,在MVC5和之前,调用'child actions'也会执行任何过滤器(例如,如果控制器在它们上面装饰了过滤器)给它们作为常规动作的外观......但是对于ViewComponents并不是这样,它们是在实际请求的上下文中执行的......
有关视图组件的更多信息:https://docs.microsoft.com/en-us/aspnet/core/mvc/views/view-components
ViewComponents很棒,但对于Ajax来说并不是那么好。
如果你真的错过了@ Html.RenderAction方法,那么这是我为AspNetCore一起进行的快速实现。
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.Internal;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Routing;
namespace Microsoft.AspNetCore.Mvc.Rendering {
public static class HtmlHelperViewExtensions
{
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, object parameters = null)
{
var controller = (string)helper.ViewContext.RouteData.Values["controller"];
return RenderAction(helper, action, controller, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, object parameters = null)
{
var area = (string)helper.ViewContext.RouteData.Values["area"];
return RenderAction(helper, action, controller, area, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
if (action == null)
throw new ArgumentNullException("action");
if (controller == null)
throw new ArgumentNullException("controller");
if (area == null)
throw new ArgumentNullException("area");
var task = RenderActionAsync(helper, action, controller, area, parameters);
return task.Result;
}
private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
// fetching required services for invocation
var currentHttpContext = helper.ViewContext?.HttpContext;
var httpContextFactory = GetServiceOrFail<IHttpContextFactory>(currentHttpContext);
var actionInvokerFactory = GetServiceOrFail<IActionInvokerFactory>(currentHttpContext);
var actionSelector = GetServiceOrFail<IActionSelectorDecisionTreeProvider>(currentHttpContext);
// creating new action invocation context
var routeData = new RouteData();
var routeParams = new RouteValueDictionary(parameters ?? new { });
var routeValues = new RouteValueDictionary(new { area = area, controller = controller, action = action });
var newHttpContext = httpContextFactory.Create(currentHttpContext.Features);
newHttpContext.Response.Body = new MemoryStream();
foreach (var router in helper.ViewContext.RouteData.Routers)
routeData.PushState(router, null, null);
routeData.PushState(null, routeValues, null);
routeData.PushState(null, routeParams, null);
var actionDescriptor = actionSelector.DecisionTree.Select(routeValues).First();
var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);
// invoke action and retreive the response body
var invoker = actionInvokerFactory.CreateInvoker(actionContext);
string content = null;
await invoker.InvokeAsync().ContinueWith(task => {
if (task.IsFaulted)
{
content = task.Exception.Message;
}
else if (task.IsCompleted)
{
newHttpContext.Response.Body.Position = 0;
using (var reader = new StreamReader(newHttpContext.Response.Body))
content = reader.ReadToEnd();
}
});
return new HtmlString(content);
}
private static TService GetServiceOrFail<TService>(HttpContext httpContext)
{
if (httpContext == null)
throw new ArgumentNullException(nameof(httpContext));
var service = httpContext.RequestServices.GetService(typeof(TService));
if (service == null)
throw new InvalidOperationException($"Could not locate service: {nameof(TService)}");
return (TService)service;
}
}
}
您可以使用以下方法之一从视图中调用:
@Html.RenderAction("action", "controller", "area", new { id = 1})
@Html.RenderAction("action", "controller", new { id = 1})
@Html.RenderAction("action", new { id = 1})
注意:
如果未提供,控制器名称和可选的区域名称将默认为ActionContext中的相应值。
更新:从2.2.2开始HttpContextAccessor将上下文保留在一个对象中(据说可以防止内部请求混淆)并且它会影响当前的解决方案......所以你需要为IHttpContextAccessor(一个旧版本)提供以下实现并注册它作为一个单身人士:
public class HttpContextAccessor : IHttpContextAccessor
{
private static AsyncLocal<HttpContext> _httpContextCurrent = new AsyncLocal<HttpContext>();
HttpContext IHttpContextAccessor.HttpContext { get => _httpContextCurrent.Value; set => _httpContextCurrent.Value = value; }
}
对于asp.net核心2
using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.IO;
using System.Threading.Tasks;
namespace Microsoft.AspNetCore.Mvc.Rendering
{
public static class HtmlHelperViewExtensions
{
public static IHtmlContent Action(this IHtmlHelper helper, string action, object parameters = null)
{
var controller = (string)helper.ViewContext.RouteData.Values["controller"];
return Action(helper, action, controller, parameters);
}
public static IHtmlContent Action(this IHtmlHelper helper, string action, string controller, object parameters = null)
{
var area = (string)helper.ViewContext.RouteData.Values["area"];
return Action(helper, action, controller, area, parameters);
}
public static IHtmlContent Action(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
if (action == null)
throw new ArgumentNullException("action");
if (controller == null)
throw new ArgumentNullException("controller");
var task = RenderActionAsync(helper, action, controller, area, parameters);
return task.Result;
}
private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
// fetching required services for invocation
var serviceProvider = helper.ViewContext.HttpContext.RequestServices;
var actionContextAccessor = helper.ViewContext.HttpContext.RequestServices.GetRequiredService<IActionContextAccessor>();
var httpContextAccessor = helper.ViewContext.HttpContext.RequestServices.GetRequiredService<IHttpContextAccessor>();
var actionSelector = serviceProvider.GetRequiredService<IActionSelector>();
// creating new action invocation context
var routeData = new RouteData();
foreach (var router in helper.ViewContext.RouteData.Routers)
{
routeData.PushState(router, null, null);
}
routeData.PushState(null, new RouteValueDictionary(new { controller = controller, action = action, area = area }), null);
routeData.PushState(null, new RouteValueDictionary(parameters ?? new { }), null);
//get the actiondescriptor
RouteContext routeContext = new RouteContext(helper.ViewContext.HttpContext) { RouteData = routeData };
var candidates = actionSelector.SelectCandidates(routeContext);
var actionDescriptor = actionSelector.SelectBestCandidate(routeContext, candidates);
var originalActionContext = actionContextAccessor.ActionContext;
var originalhttpContext = httpContextAccessor.HttpContext;
try
{
var newHttpContext = serviceProvider.GetRequiredService<IHttpContextFactory>().Create(helper.ViewContext.HttpContext.Features);
if (newHttpContext.Items.ContainsKey(typeof(IUrlHelper)))
{
newHttpContext.Items.Remove(typeof(IUrlHelper));
}
newHttpContext.Response.Body = new MemoryStream();
var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);
actionContextAccessor.ActionContext = actionContext;
var invoker = serviceProvider.GetRequiredService<IActionInvokerFactory>().CreateInvoker(actionContext);
await invoker.InvokeAsync();
newHttpContext.Response.Body.Position = 0;
using (var reader = new StreamReader(newHttpContext.Response.Body))
{
return new HtmlString(reader.ReadToEnd());
}
}
catch (Exception ex)
{
return new HtmlString(ex.Message);
}
finally
{
actionContextAccessor.ActionContext = originalActionContext;
httpContextAccessor.HttpContext = originalhttpContext;
if (helper.ViewContext.HttpContext.Items.ContainsKey(typeof(IUrlHelper)))
{
helper.ViewContext.HttpContext.Items.Remove(typeof(IUrlHelper));
}
}
}
}
}
它基于白羊座的反应。我纠正了没有编译2.0的内容,我添加了几个调整。当前的httpcontext和当前的actioncontext有2个美化的静态值。 httpcontext的一个在IHttpContextFactory.Create
中设置,我在代码中为actioncontext设置了一个。请注意,根据您使用的功能,IActionContextAccessor
和IHttpContextAccessor
默认情况下可能未注册,因此您可能需要在启动时添加它们:
services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
HttpContext只是HttpContext.Features
的一个包装器,所以如果你改变一个中的东西,它也会在另一个中改变...我在try / catch的finally中重置我所知道的。
我从Items缓存中删除了IUrlHelper
,因为即使构建urlHelper的actionContext不同(IUrlHelperFactory.GetUrlHelper
),该值也将被重用。
Asp.net核心2.0假设你不会这样做,很有可能还有其他缓存的东西,所以我建议在使用它时要小心,如果你不需要,就不要这样做。
对于Net Core 2.0
using Microsoft.AspNetCore.Mvc.Infrastructure;
更换
// var actionSelector = GetServiceOrFail<IActionSelectorDecisionTreeProvider>(currentHttpContext);
var actionSelector = GetServiceOrFail<IActionDescriptorCollectionProvider>(currentHttpContext);
和
// var actionDescriptor = actionSelector.DecisionTree.Select(routeValues).First();
var actionDescriptor = actionSelector.ActionDescriptors.Items.Where(i => i.RouteValues["Controller"] == controller && i.RouteValues["Action"] == action).First();
由于IActionSelectorDecisionTreeProvider已从较新版本中删除,因此Aries for Helper Extension的解决方法对Net Core 2.0来说不再适用。请参阅以下链接。
https://github.com/Microsoft/aspnet-api-versioning/issues/154
对于Yepeekai提供的asp.net core 2解决方案,请在Startup.cs中添加以下内容:
services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();
默认情况下,2.0中不再注册。
我使用此页面上的人员代码来获得正确的结果。
https://stackoverflow.com/a/39951006/6778726
https://stackoverflow.com/a/46859170/6778726
例如,在旧类中,执行以下代码时,显示错误
@Html.RenderAction("About", "Home")
以下代码已修复:
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Routing;
namespace Microsoft.AspNetCore.Mvc.Rendering
{
public static class HtmlHelperViewExtensions
{
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, object parameters = null)
{
var controller = (string)helper.ViewContext.RouteData.Values["controller"];
return RenderAction(helper, action, controller, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, object parameters = null)
{
var area = (string)helper.ViewContext.RouteData.Values["area"];
return RenderAction(helper, action, controller, area, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
if (action == null)
throw new ArgumentNullException(nameof(controller));
if (controller == null)
throw new ArgumentNullException(nameof(action));
var task = RenderActionAsync(helper, action, controller, area, parameters);
return task.Result;
}
private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
// fetching required services for invocation
var currentHttpContext = helper.ViewContext.HttpContext;
var httpContextFactory = GetServiceOrFail<IHttpContextFactory>(currentHttpContext);
var actionInvokerFactory = GetServiceOrFail<IActionInvokerFactory>(currentHttpContext);
var actionSelector = GetServiceOrFail<IActionDescriptorCollectionProvider>(currentHttpContext);
// creating new action invocation context
var routeData = new RouteData();
var routeParams = new RouteValueDictionary(parameters ?? new { });
var routeValues = new RouteValueDictionary(new { area, controller, action });
var newHttpContext = httpContextFactory.Create(currentHttpContext.Features);
newHttpContext.Response.Body = new MemoryStream();
foreach (var router in helper.ViewContext.RouteData.Routers)
routeData.PushState(router, null, null);
routeData.PushState(null, routeValues, null);
routeData.PushState(null, routeParams, null);
var actionDescriptor = actionSelector.ActionDescriptors.Items.First(i => i.RouteValues["Controller"] == controller && i.RouteValues["Action"] == action);
var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);
// invoke action and retreive the response body
var invoker = actionInvokerFactory.CreateInvoker(actionContext);
string content = null;
await invoker.InvokeAsync().ContinueWith(task =>
{
if (task.IsFaulted)
{
content = task.Exception.Message;
}
else if (task.IsCompleted)
{
newHttpContext.Response.Body.Position = 0;
using (var reader = new StreamReader(newHttpContext.Response.Body))
content = reader.ReadToEnd();
}
});
return new HtmlString(content);
}
private static TService GetServiceOrFail<TService>(HttpContext httpContext)
{
if (httpContext == null)
throw new ArgumentNullException(nameof(httpContext));
var service = httpContext.RequestServices.GetService(typeof(TService));
if (service == null)
throw new InvalidOperationException($"Could not locate service: {nameof(TService)}");
return (TService)service;
}
}
}
以下示例已成功测试:
@Html.RenderAction("About")
@Html.RenderAction("About", "Home")
@Html.RenderAction("About", new { data1 = "test1", data2 = "test2" })
@Html.RenderAction("About", "Home", new { data1 = "test1", data2 = "test2" })