如何在不等待长时间运行的过程的情况下运行方法 [英] How can I run a method without waiting for long running process

问题描述

我有一个Layout，其中有一个@RenderBody部分和一个index页面.我的索引页运行时间很长，我希望它无需等待DoSomeAsyncStuff就可以呈现视图.下面的代码看起来很接近我想要的代码，但是问题出在我的模型上，当传递给视图时，它的属性为null:

I have a Layout with a @RenderBody section and an index page. My index page has a long running process and I want it renders the view without waiting for DoSomeAsyncStuff. The following code looks close to what I want but the problem is with my model that it's properties are null when pass to view:

public ActionResult Index()
{
    MyModel model = new MyModel();
    Task.Run(() => DoSomeAsyncStuff(model));
    return View(model);
}

private async void DoSomeAsyncStuff(MyModel model)
{
    await Task.Delay(20000);
    model.Name = "Something";
    //Assigning other model properties
}

在我看来，我得到NullReferenceException和Value cannot be null错误，这肯定是因为我的模型属性仍未填充在DoSomeAsyncStuff方法中:

Here in my view I get NullReferenceException and Value cannot be null errors and certainly it is because my model's properties are not still filled in the DoSomeAsyncStuff method:

<table>
<tr>
    <th colspan="3">
        @Model.Products.Select(c => c.Date).FirstOrDefault()
    </th>

</tr>

@foreach (var item in Model.Products)
{
    <tr>
        <td>
            @item.Title
        </td>
        <td>
            @item.Price
        </td>
    </tr>
}
</table>

推荐答案

您尚未显示模型，因此这大部分是伪代码.首先，将长期运行的内容移至另一个动作:

You haven't shown your model, so this will be mostly pseudo-code. First, move the long-running stuff to another action:

public ActionResult Index()
{
    var model = new MyModel();

    return View(model);
}

public async Task<ActionResult> DoSomeAsyncStuff()
{
    var model = new MyModel();
    await Task.Delay(20000);

    model.Name = "Something";
    //Assigning other model properties

    return PartialView("_InnerView", model);
}

所有与模型绑定的内容都应在局部视图中(这里我称之为_InnerView.cshtml).父视图应该只包含一个占位符或加载小部件，您的模型绑定标记当前位于该位置:

Everything that is model-bound should be in the partial view (what I'm calling _InnerView.cshtml, here). The parent view should just have a placeholder or loading widget where your model-bound markup currently resides:

<div id="load-with-ajax">
    Please wait. Loading...
</div>

然后，在页面的某处，在您的jQuery引用之后(假设您正在使用jQuery或愿意使用jQuery)，添加以下内容:

Then, somewhere in the page, after your jQuery reference (I'm assuming you're using jQuery or are willing to), add something like:

<script>
    $(function(){
        $('#load-with-ajax').load('@Url.Action("DoSomeAsyncStuff")');
    });
</script>

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