$. getJSON 返回 IE8中的缓存数据

目前我正在使用 ASP.net MVC 和 JQuery。我遇到过一些不合常理的行为。

我正在调用 JQuery 的 $.getJSON函数来填充一些 div。事件在 $(document).ready事件上被触发。

有一个小的 AJAX.BeginForm，它添加了另一个值，以便在填充 div 时使用。它正确地调用远程函数，并在成功时调用原来的 javascript 函数来重新填充 div。

这就是奇怪的地方: 在 FireFox 和 Chrome 中，所有的东西都可以工作。但是在 IE8(Beta)中，第二次调用填充 Div 脚本(调用 $。GetJSON 函数)获取缓存数据并且不要求服务器！

希望这个问题是有意义的: 简而言之——为什么 $.getJSON会得到缓存数据？为什么它只影响 IE8？

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You may need to send a cache-breaker.

I would recommend using $.ajax( { cache: no }) just in case ( adds a random suffix to the get request)

( I tend to use $.ajax everywhere these days, more tuneable )

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Thanks Kent for your answer. Using $.ajax('{ cache: no }'); worked perfectly. [edit]

Or at least I thought i did. Seems that the jquery $.getJSON isn't reading any changes made to the $.ajax object.

The solution that ended up working was to add a new parameter manually

var noCache = Date();
$.getJSON("/somepage/someaction", { "noCache": noCache }, Callback);

the date resolution is only to the minute; which effectively means this solution still caches for upto one minute. This is acceptable for my purposes.

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最佳答案

Just to let you know, Firefox and Chrome consider all Ajax request as non-cachable. IE (all versions) treat Ajax call just as other web request. That's why you see this behavior.
How to force IE to download data at each request:

  • As you said, use 'cache' or 'nocache' option in JQuery
  • Add a random parameter to the request (ugly, but works :))
  • On server side, set cachability (for example using an attribute, see below)

Code:

public class NoCacheAttribute : ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext context)
{
context.HttpContext.Response.Cache.SetCacheability(HttpCacheability.NoCache);
}
}
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This is how it worked for me...

$.ajaxSetup({ cache: false });
$.getJSON("/MyQueryUrl",function(data,item) {
// do stuff with callback data
$.ajaxSetup({ cache: true });
});
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If you're using ASP.net MVC, consider adding an extension method to easily implement no caching like so: 

    public static void NoCache(this HttpResponse Response)
{
Response.Cache.SetNoStore();
Response.Cache.SetExpires(DateTime.MinValue);
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetValidUntilExpires(false);


Response.Expires = -1;
Response.ExpiresAbsolute = DateTime.MinValue;
Response.AddHeader("Cache-Control", "no-cache");
Response.AddHeader("Pragma", "no-cache");
}
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I solved this same problem by placing the following attribute on the Action in the Controller:

[OutputCache(Duration = 0, VaryByParam = "None")]
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Ready for THE answer ?

http://lestopher.tumblr.com/post/21742012438/if-youre-using-ie8-and-getjson

So, just add 

jQuery.support.cors = true;

at the beginning of your script and BANG it works !


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