我在我的_Layout.cshtml中定义了这个部分
@RenderSection("Scripts", false)
我可以很容易地从视图中使用它:
@section Scripts {
@*Stuff comes here*@
}
我正在努力解决的问题是如何从局部视图将一些内容注入到这个部分中。
让我们假设这是我的视图页面:
@section Scripts {
<script>
//code comes here
</script>
}
<div>
poo bar poo
</div>
<div>
@Html.Partial("_myPartial")
</div>
我需要在脚本部分中从_myPartial partial视图中注入一些内容。
我该怎么做呢?
当前回答
你可以使用这些扩展方法:(保存为PartialWithScript.cs)
namespace System.Web.Mvc.Html
{
public static class PartialWithScript
{
public static void RenderPartialWithScript(this HtmlHelper htmlHelper, string partialViewName)
{
if (htmlHelper.ViewBag.ScriptPartials == null)
{
htmlHelper.ViewBag.ScriptPartials = new List<string>();
}
if (!htmlHelper.ViewBag.ScriptPartials.Contains(partialViewName))
{
htmlHelper.ViewBag.ScriptPartials.Add(partialViewName);
}
htmlHelper.ViewBag.ScriptPartialHtml = true;
htmlHelper.RenderPartial(partialViewName);
}
public static void RenderPartialScripts(this HtmlHelper htmlHelper)
{
if (htmlHelper.ViewBag.ScriptPartials != null)
{
htmlHelper.ViewBag.ScriptPartialHtml = false;
foreach (string partial in htmlHelper.ViewBag.ScriptPartials)
{
htmlHelper.RenderPartial(partial);
}
}
}
}
}
像这样使用:
示例partial:(_MyPartial.cshtml) 把html放在if里，js放在else里。
@if (ViewBag.ScriptPartialHtml ?? true)
<p>I has htmls</p>
}
else {
<script type="text/javascript">
alert('I has javascripts');
</script>
}
在你的_Layout中。cshtml，或者任何你想要渲染的部分脚本的地方，放置以下(一次):它将只在当前页面的这个位置渲染所有部分的javascript。
@{ Html.RenderPartialScripts(); }
然后使用您的部分，只需这样做:它将只呈现该位置的html。
@{Html.RenderPartialWithScript("~/Views/MyController/_MyPartial.cshtml");}
其他回答
我解决这个完全不同的路线(因为我很着急，不想实现一个新的HtmlHelper):
我用一个大的if-else语句包装了我的Partial View:
@if ((bool)ViewData["ShouldRenderScripts"] == true){
// Scripts
}else{
// Html
}
然后，我用自定义ViewData调用了两次Partial:
@Html.Partial("MyPartialView", Model,
new ViewDataDictionary { { "ShouldRenderScripts", false } })
@section scripts{
@Html.Partial("MyPartialView", Model,
new ViewDataDictionary { { "ShouldRenderScripts", true } })
}
从这个线程中的解决方案，我提出了以下可能过于复杂的解决方案，让你延迟渲染任何html(脚本)在一个using块。
使用
创建section
Typical scenario: In a partial view, only include the block one time no matter how many times the partial view is repeated in the page: @using (Html.Delayed(isOnlyOne: "some unique name for this section")) { <script> someInlineScript(); </script> } In a partial view, include the block for every time the partial is used: @using (Html.Delayed()) { <b>show me multiple times, @Model.Whatever</b> } In a partial view, only include the block once no matter how many times the partial is repeated, but later render it specifically by name when-i-call-you: @using (Html.Delayed("when-i-call-you", isOnlyOne: "different unique name")) { <b>show me once by name</b> <span>@Model.First().Value</span> }
渲染“sections”
(即在父视图中显示延迟的部分)
@Html.RenderDelayed(); // writes unnamed sections (#1 and #2, excluding #3)
@Html.RenderDelayed("when-i-call-you", false); // writes the specified block, and ignore the `isOnlyOne` setting so we can dump it again
@Html.RenderDelayed("when-i-call-you"); // render the specified block by name
@Html.RenderDelayed("when-i-call-you"); // since it was "popped" in the last call, won't render anything due to `isOnlyOne` provided in `Html.Delayed`
CODE
public static class HtmlRenderExtensions {
/// <summary>
/// Delegate script/resource/etc injection until the end of the page
/// <para>@via https://stackoverflow.com/a/14127332/1037948 and http://jadnb.wordpress.com/2011/02/16/rendering-scripts-from-partial-views-at-the-end-in-mvc/ </para>
/// </summary>
private class DelayedInjectionBlock : IDisposable {
/// <summary>
/// Unique internal storage key
/// </summary>
private const string CACHE_KEY = "DCCF8C78-2E36-4567-B0CF-FE052ACCE309"; // "DelayedInjectionBlocks";
/// <summary>
/// Internal storage identifier for remembering unique/isOnlyOne items
/// </summary>
private const string UNIQUE_IDENTIFIER_KEY = CACHE_KEY;
/// <summary>
/// What to use as internal storage identifier if no identifier provided (since we can't use null as key)
/// </summary>
private const string EMPTY_IDENTIFIER = "";
/// <summary>
/// Retrieve a context-aware list of cached output delegates from the given helper; uses the helper's context rather than singleton HttpContext.Current.Items
/// </summary>
/// <param name="helper">the helper from which we use the context</param>
/// <param name="identifier">optional unique sub-identifier for a given injection block</param>
/// <returns>list of delayed-execution callbacks to render internal content</returns>
public static Queue<string> GetQueue(HtmlHelper helper, string identifier = null) {
return _GetOrSet(helper, new Queue<string>(), identifier ?? EMPTY_IDENTIFIER);
}
/// <summary>
/// Retrieve a context-aware list of cached output delegates from the given helper; uses the helper's context rather than singleton HttpContext.Current.Items
/// </summary>
/// <param name="helper">the helper from which we use the context</param>
/// <param name="defaultValue">the default value to return if the cached item isn't found or isn't the expected type; can also be used to set with an arbitrary value</param>
/// <param name="identifier">optional unique sub-identifier for a given injection block</param>
/// <returns>list of delayed-execution callbacks to render internal content</returns>
private static T _GetOrSet<T>(HtmlHelper helper, T defaultValue, string identifier = EMPTY_IDENTIFIER) where T : class {
var storage = GetStorage(helper);
// return the stored item, or set it if it does not exist
return (T) (storage.ContainsKey(identifier) ? storage[identifier] : (storage[identifier] = defaultValue));
}
/// <summary>
/// Get the storage, but if it doesn't exist or isn't the expected type, then create a new "bucket"
/// </summary>
/// <param name="helper"></param>
/// <returns></returns>
public static Dictionary<string, object> GetStorage(HtmlHelper helper) {
var storage = helper.ViewContext.HttpContext.Items[CACHE_KEY] as Dictionary<string, object>;
if (storage == null) helper.ViewContext.HttpContext.Items[CACHE_KEY] = (storage = new Dictionary<string, object>());
return storage;
}
private readonly HtmlHelper helper;
private readonly string identifier;
private readonly string isOnlyOne;
/// <summary>
/// Create a new using block from the given helper (used for trapping appropriate context)
/// </summary>
/// <param name="helper">the helper from which we use the context</param>
/// <param name="identifier">optional unique identifier to specify one or many injection blocks</param>
/// <param name="isOnlyOne">extra identifier used to ensure that this item is only added once; if provided, content should only appear once in the page (i.e. only the first block called for this identifier is used)</param>
public DelayedInjectionBlock(HtmlHelper helper, string identifier = null, string isOnlyOne = null) {
this.helper = helper;
// start a new writing context
((WebViewPage)this.helper.ViewDataContainer).OutputStack.Push(new StringWriter());
this.identifier = identifier ?? EMPTY_IDENTIFIER;
this.isOnlyOne = isOnlyOne;
}
/// <summary>
/// Append the internal content to the context's cached list of output delegates
/// </summary>
public void Dispose() {
// render the internal content of the injection block helper
// make sure to pop from the stack rather than just render from the Writer
// so it will remove it from regular rendering
var content = ((WebViewPage)this.helper.ViewDataContainer).OutputStack;
var renderedContent = content.Count == 0 ? string.Empty : content.Pop().ToString();
// if we only want one, remove the existing
var queue = GetQueue(this.helper, this.identifier);
// get the index of the existing item from the alternate storage
var existingIdentifiers = _GetOrSet(this.helper, new Dictionary<string, int>(), UNIQUE_IDENTIFIER_KEY);
// only save the result if this isn't meant to be unique, or
// if it's supposed to be unique and we haven't encountered this identifier before
if( null == this.isOnlyOne || !existingIdentifiers.ContainsKey(this.isOnlyOne) ) {
// remove the new writing context we created for this block
// and save the output to the queue for later
queue.Enqueue(renderedContent);
// only remember this if supposed to
if(null != this.isOnlyOne) existingIdentifiers[this.isOnlyOne] = queue.Count; // save the index, so we could remove it directly (if we want to use the last instance of the block rather than the first)
}
}
}
/// <summary>
/// <para>Start a delayed-execution block of output -- this will be rendered/printed on the next call to <see cref="RenderDelayed"/>.</para>
/// <para>
/// <example>
/// Print once in "default block" (usually rendered at end via <code>@Html.RenderDelayed()</code>). Code:
/// <code>
/// @using (Html.Delayed()) {
/// <b>show at later</b>
/// <span>@Model.Name</span>
/// etc
/// }
/// </code>
/// </example>
/// </para>
/// <para>
/// <example>
/// Print once (i.e. if within a looped partial), using identified block via <code>@Html.RenderDelayed("one-time")</code>. Code:
/// <code>
/// @using (Html.Delayed("one-time", isOnlyOne: "one-time")) {
/// <b>show me once</b>
/// <span>@Model.First().Value</span>
/// }
/// </code>
/// </example>
/// </para>
/// </summary>
/// <param name="helper">the helper from which we use the context</param>
/// <param name="injectionBlockId">optional unique identifier to specify one or many injection blocks</param>
/// <param name="isOnlyOne">extra identifier used to ensure that this item is only added once; if provided, content should only appear once in the page (i.e. only the first block called for this identifier is used)</param>
/// <returns>using block to wrap delayed output</returns>
public static IDisposable Delayed(this HtmlHelper helper, string injectionBlockId = null, string isOnlyOne = null) {
return new DelayedInjectionBlock(helper, injectionBlockId, isOnlyOne);
}
/// <summary>
/// Render all queued output blocks injected via <see cref="Delayed"/>.
/// <para>
/// <example>
/// Print all delayed blocks using default identifier (i.e. not provided)
/// <code>
/// @using (Html.Delayed()) {
/// <b>show me later</b>
/// <span>@Model.Name</span>
/// etc
/// }
/// </code>
/// -- then later --
/// <code>
/// @using (Html.Delayed()) {
/// <b>more for later</b>
/// etc
/// }
/// </code>
/// -- then later --
/// <code>
/// @Html.RenderDelayed() // will print both delayed blocks
/// </code>
/// </example>
/// </para>
/// <para>
/// <example>
/// Allow multiple repetitions of rendered blocks, using same <code>@Html.Delayed()...</code> as before. Code:
/// <code>
/// @Html.RenderDelayed(removeAfterRendering: false); /* will print */
/// @Html.RenderDelayed() /* will print again because not removed before */
/// </code>
/// </example>
/// </para>
/// </summary>
/// <param name="helper">the helper from which we use the context</param>
/// <param name="injectionBlockId">optional unique identifier to specify one or many injection blocks</param>
/// <param name="removeAfterRendering">only render this once</param>
/// <returns>rendered output content</returns>
public static MvcHtmlString RenderDelayed(this HtmlHelper helper, string injectionBlockId = null, bool removeAfterRendering = true) {
var stack = DelayedInjectionBlock.GetQueue(helper, injectionBlockId);
if( removeAfterRendering ) {
var sb = new StringBuilder(
#if DEBUG
string.Format("<!-- delayed-block: {0} -->", injectionBlockId)
#endif
);
// .count faster than .any
while (stack.Count > 0) {
sb.AppendLine(stack.Dequeue());
}
return MvcHtmlString.Create(sb.ToString());
}
return MvcHtmlString.Create(
#if DEBUG
string.Format("<!-- delayed-block: {0} -->", injectionBlockId) +
#endif
string.Join(Environment.NewLine, stack));
}
}
这是一个很常见的问题，所以我会把我的答案贴出来。
我也遇到过同样的问题，虽然它不是理想的，但我认为它实际上工作得很好，并且不使部分依赖于视图。
我的场景是，一个动作本身是可访问的，但也可以嵌入到一个视图中——一个谷歌映射。
在我的_layout中我有:
@RenderSection("body_scripts", false)
在我的索引视图中有:
@Html.Partial("Clients")
@section body_scripts
{
@Html.Partial("Clients_Scripts")
}
在我的客户视图中，我有(所有的地图和assoc。html):
@section body_scripts
{
@Html.Partial("Clients_Scripts")
}
我的Clients_Scripts视图包含要呈现到页面上的javascript。
通过这种方式，我的脚本是隔离的，并且可以在需要的地方呈现到页面中，而body_scripts标记只在razor视图引擎第一次发现它时呈现。
这让我把所有东西都分开了——这对我来说是一个很好的解决方案，其他人可能有问题，但它确实修补了“设计”的漏洞。
你可以使用这些扩展方法:(保存为PartialWithScript.cs)
namespace System.Web.Mvc.Html
{
public static class PartialWithScript
{
public static void RenderPartialWithScript(this HtmlHelper htmlHelper, string partialViewName)
{
if (htmlHelper.ViewBag.ScriptPartials == null)
{
htmlHelper.ViewBag.ScriptPartials = new List<string>();
}
if (!htmlHelper.ViewBag.ScriptPartials.Contains(partialViewName))
{
htmlHelper.ViewBag.ScriptPartials.Add(partialViewName);
}
htmlHelper.ViewBag.ScriptPartialHtml = true;
htmlHelper.RenderPartial(partialViewName);
}
public static void RenderPartialScripts(this HtmlHelper htmlHelper)
{
if (htmlHelper.ViewBag.ScriptPartials != null)
{
htmlHelper.ViewBag.ScriptPartialHtml = false;
foreach (string partial in htmlHelper.ViewBag.ScriptPartials)
{
htmlHelper.RenderPartial(partial);
}
}
}
}
}
像这样使用:
示例partial:(_MyPartial.cshtml) 把html放在if里，js放在else里。
@if (ViewBag.ScriptPartialHtml ?? true)
<p>I has htmls</p>
}
else {
<script type="text/javascript">
alert('I has javascripts');
</script>
}
在你的_Layout中。cshtml，或者任何你想要渲染的部分脚本的地方，放置以下(一次):它将只在当前页面的这个位置渲染所有部分的javascript。
@{ Html.RenderPartialScripts(); }
然后使用您的部分，只需这样做:它将只呈现该位置的html。
@{Html.RenderPartialWithScript("~/Views/MyController/_MyPartial.cshtml");}
假设您有一个称为_contact的部分视图。Cshtml，您的联系人可以是合法的(姓名)或物理主体(名，姓)。你的视图应该关心被渲染的内容，这可以用javascript实现。所以延迟渲染和JS内部视图可能需要。
我认为唯一可以忽略它的方法是，当我们创建一种不引人注目的方式来处理这种UI关注点时。
还要注意MVC 6将有一个所谓的视图组件，甚至MVC未来也有一些类似的东西，Telerik也支持这样的东西…
