asp.net core mvc @Html.Action

1、创建 静态类 HtmlHelperViewExtensions，其命名空间为  Microsoft.AspNetCore.Mvc.Rendering。这样我们直接用@Html直接可以 使用Action方法了。

{
    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));
                }
            }
        }
    }
}

2、 在Startup中的 ConfigureServices 方法添加：

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor();

services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();

（备注：因为net core 默认不将IHttpContextAccessor，IActionContextAccessor 依赖注入，所以需要手动进行依赖注入）

3、在页面中，我们就可以直接用 @Html.Action()方法 直接请求 控制器的方法了。

作者：大坤儿
链接：https://www.jianshu.com/p/f44a19960549