C# IView.RenderAsync方法代码示例

        /// <summary>
        /// Asynchronously renders the specified <paramref name="view"/> to the response body.
        /// </summary>
        /// <param name="view">The <see cref="IView"/> to render.</param>
        /// <param name="actionContext">The <see cref="ActionContext"/> for the current executing action.</param>
        /// <param name="viewData">The <see cref="ViewDataDictionary"/> for the view being rendered.</param>
        /// <param name="tempData">The <see cref="ITempDataDictionary"/> for the view being rendered.</param>
        /// <returns>A <see cref="Task"/> that represents the asynchronous rendering.</returns>
        public static async Task ExecuteAsync(
            IView view,
            ActionContext actionContext,
            ViewDataDictionary viewData,
            ITempDataDictionary tempData,
            HtmlHelperOptions htmlHelperOptions,
            MediaTypeHeaderValue contentType)
        {
            if (view == null)
            {
                throw new ArgumentNullException(nameof(view));
            }

            if (actionContext == null)
            {
                throw new ArgumentNullException(nameof(actionContext));
            }

            if (viewData == null)
            {
                throw new ArgumentNullException(nameof(viewData));
            }

            if (tempData == null)
            {
                throw new ArgumentNullException(nameof(tempData));
            }

            if (htmlHelperOptions == null)
            {
                throw new ArgumentNullException(nameof(htmlHelperOptions));
            }

            var response = actionContext.HttpContext.Response;

            if (contentType != null && contentType.Encoding == null)
            {
                // Do not modify the user supplied content type, so copy it instead
                contentType = contentType.Copy();
                contentType.Encoding = Encoding.UTF8;
            }

            // Priority list for setting content-type:
            //      1. passed in contentType (likely set by the user on the result)
            //      2. response.ContentType (likely set by the user in controller code)
            //      3. ViewExecutor.DefaultContentType (sensible default)
            response.ContentType = contentType?.ToString() ?? response.ContentType ?? DefaultContentType.ToString();

            using (var writer = new HttpResponseStreamWriter(response.Body, contentType?.Encoding ?? DefaultContentType.Encoding))
            {
                var viewContext = new ViewContext(
                    actionContext,
                    view,
                    viewData,
                    tempData,
                    writer,
                    htmlHelperOptions);

                await view.RenderAsync(viewContext);
                // Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
                // response. In the absence of this line, the buffer gets synchronously written to the response
                // as part of the Dispose which has a perf impact.
                await writer.FlushAsync();
            }
        }

        /// <summary>
        /// Executes a view asynchronously.
        /// </summary>
        /// <param name="actionContext">The <see cref="ActionContext"/> associated with the current request.</param>
        /// <param name="view">The <see cref="IView"/>.</param>
        /// <param name="viewData">The <see cref="ViewDataDictionary"/>.</param>
        /// <param name="tempData">The <see cref="ITempDataDictionary"/>.</param>
        /// <param name="contentType">
        /// The content-type header value to set in the response. If <c>null</c>,
        /// <see cref="DefaultContentType"/> will be used.
        /// </param>
        /// <param name="statusCode">
        /// The HTTP status code to set in the response. May be <c>null</c>.
        /// </param>
        /// <returns>A <see cref="Task"/> which will complete when view execution is completed.</returns>
        public virtual async Task ExecuteAsync(
            ActionContext actionContext,
            IView view,
            ViewDataDictionary viewData,
            ITempDataDictionary tempData,
            string contentType,
            int? statusCode)
        {
            if (actionContext == null)
            {
                throw new ArgumentNullException(nameof(actionContext));
            }

            if (view == null)
            {
                throw new ArgumentNullException(nameof(view));
            }

            if (viewData == null)
            {
                var services = actionContext.HttpContext.RequestServices;
                var metadataProvider = services.GetRequiredService<IModelMetadataProvider>();
                viewData = new ViewDataDictionary(metadataProvider, actionContext.ModelState);
            }

            if (tempData == null)
            {
                tempData = TempDataFactory.GetTempData(actionContext.HttpContext);
            }

            var response = actionContext.HttpContext.Response;

            string resolvedContentType = null;
            Encoding resolvedContentTypeEncoding = null;
            ResponseContentTypeHelper.ResolveContentTypeAndEncoding(
                contentType,
                response.ContentType,
                DefaultContentType,
                out resolvedContentType,
                out resolvedContentTypeEncoding);

            response.ContentType = resolvedContentType;

            if (statusCode != null)
            {
                response.StatusCode = statusCode.Value;
            }

            using (var writer = WriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
            {
                var viewContext = new ViewContext(
                    actionContext,
                    view,
                    viewData,
                    tempData,
                    writer,
                    ViewOptions.HtmlHelperOptions);

                DiagnosticSource.BeforeView(view, viewContext);

                await view.RenderAsync(viewContext);

                DiagnosticSource.AfterView(view, viewContext);

                // Perf: Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
                // response asynchronously. In the absence of this line, the buffer gets synchronously written to the
                // response as part of the Dispose which has a perf impact.
                await writer.FlushAsync();
            }
        }

        /// <summary>
        /// Executes a view asynchronously.
        /// </summary>
        /// <param name="actionContext">The <see cref="ActionContext"/> associated with the current request.</param>
        /// <param name="view">The <see cref="IView"/>.</param>
        /// <param name="viewData">The <see cref="ViewDataDictionary"/>.</param>
        /// <param name="tempData">The <see cref="ITempDataDictionary"/>.</param>
        /// <param name="contentType">
        /// The content-type header value to set in the response. If <c>null</c>, <see cref="DefaultContentType"/> will be used.
        /// </param>
        /// <param name="statusCode">
        /// The HTTP status code to set in the response. May be <c>null</c>.
        /// </param>
        /// <returns>A <see cref="Task"/> which will complete when view execution is completed.</returns>
        public virtual async Task ExecuteAsync(
            ActionContext actionContext,
            IView view,
            ViewDataDictionary viewData,
            ITempDataDictionary tempData,
            MediaTypeHeaderValue contentType,
            int? statusCode)
        {
            if (actionContext == null)
            {
                throw new ArgumentNullException(nameof(actionContext));
            }

            if (view == null)
            {
                throw new ArgumentNullException(nameof(view));
            }

            var services = actionContext.HttpContext.RequestServices;
            if (viewData == null)
            {
                var metadataProvider = services.GetRequiredService<IModelMetadataProvider>();
                viewData = new ViewDataDictionary(metadataProvider);
            }

            if (tempData == null)
            {
                tempData = services.GetRequiredService<ITempDataDictionary>();
            }

            var response = actionContext.HttpContext.Response;

            if (contentType != null && contentType.Encoding == null)
            {
                // Do not modify the user supplied content type, so copy it instead
                contentType = contentType.Copy();
                contentType.Encoding = Encoding.UTF8;
            }

            // Priority list for setting content-type:
            //      1. passed in contentType (likely set by the user on the result)
            //      2. response.ContentType (likely set by the user in controller code)
            //      3. ViewExecutor.DefaultContentType (sensible default)
            response.ContentType = contentType?.ToString() ?? response.ContentType ?? DefaultContentType.ToString();

            if (statusCode != null)
            {
                response.StatusCode = statusCode.Value;
            }

            var encoding = contentType?.Encoding ?? DefaultContentType.Encoding;
            using (var writer = WriterFactory.CreateWriter(response.Body, encoding))
            {
                var viewContext = new ViewContext(
                    actionContext,
                    view,
                    viewData,
                    tempData,
                    writer,
                    ViewOptions.HtmlHelperOptions);
                
                DiagnosticSource.BeforeView(view, viewContext);

                await view.RenderAsync(viewContext);

                DiagnosticSource.AfterView(view, viewContext);

                // Perf: Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
                // response asynchronously. In the absence of this line, the buffer gets synchronously written to the
                // response as part of the Dispose which has a perf impact.
                await writer.FlushAsync();
            }
        }