Question

我正在尝试在我的Web应用程序中创建一个模型（MV中的M）来理解这个概念。我正在努力解决下面代码中出现的异步问题：

 string unitsMap[] = { "zero", "one", "two", "three", "four", "five","six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
string tensMap[] = { "zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" };

string NumberToWords(int number)
{
 if (number == 0)
    return "zero";

if (number < 0)
    return "minus " + NumberToWords(abs(number));

string words = "";

if ((number / 1000000000) > 0)
{
    words += NumberToWords(number / 1000000000) + " billion ";
    number %= 1000000000;
}

if ((number / 1000000) > 0)
{
    words += NumberToWords(number / 1000000) + " million ";
    number %= 1000000;
}

if ((number / 1000) > 0)
{
    words += NumberToWords(number / 1000) + " thousand ";
    number %= 1000;
}

if ((number / 100) > 0)
{
    words += NumberToWords(number / 100) + " hundred ";
    number %= 100;
}

if (number > 0)
{
    if (number < 20)
        words += unitsMap[number];
    else
    {
        words += tensMap[number / 10];
        if ((number % 10) > 0)
            words += "-" + unitsMap[number % 10];
    }
}

return words;
 }

我知道这是错误的，因为console.log将在getJSON完成之前发生，因为这是异步的。我应该如何设计这个来防止这个问题？

我认为获取前端MVC的实际数据是从模型中从等于我的RESTapi访问它。是否有一个首选的解决方案而不是像我一样在模型中执行此操作？

Answer 1

您可以发送回调函数并在完成异步代码后执行它：

 try
            {
                string htmlContent = TextBox1.Text.Replace("\r", "\n").Replace("\n", "");// you html code (for example table from your page)
                Document doc = new Document();
                string FileName = Guid.NewGuid().ToString();
                PdfWriter writer = PdfWriter.GetInstance(doc, new FileStream("C:\\Nikhil Shah\\Projects\\Local Projects\\PracticeDemo\\PracticeDemo\\PDF\\" + FileName + ".pdf", FileMode.Create));
                doc.Open();
                var cssResolver = new StyleAttrCSSResolver();
                var cssFile = XMLWorkerHelper.GetCSS(new FileStream(HttpContext.Current.Server.MapPath(@"~\Content\myCss.css"), FileMode.Open));
                cssResolver.AddCss(cssFile);


                CssAppliers ca = new CssAppliersImpl();
                HtmlPipelineContext hpc = new HtmlPipelineContext(ca);
                hpc.SetTagFactory(Tags.GetHtmlTagProcessorFactory());

                // PIPELINES
                PdfWriterPipeline pdf = new PdfWriterPipeline(doc, writer);
                HtmlPipeline htmlPipe = new HtmlPipeline(hpc, pdf);
                CssResolverPipeline css = new CssResolverPipeline(cssResolver, htmlPipe);

                XMLWorker worker = new XMLWorker(css, true);
                XMLParser p = new XMLParser(worker);
                StringReader sr = new StringReader(htmlContent);
                p.Parse(sr);
                doc.Close();

                Response.ContentType = "application/pdf";
                Response.AppendHeader("Content-Disposition", "attachment; filename=" + FileName + ".pdf");
                Response.TransmitFile(Server.MapPath(@"~\PDF\" + FileName + ".pdf"));
                Response.End();
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message.ToString());
            }

Answer 2

为了避免这个问题，您可以执行以下操作（因为从jQuery 1.5 .getJSON实现了Promise接口）

function FruitModel(api) {
    this._api = api;
}

FruitModel.prototype = {
    getFruit: function(fruit_id) {
       return $.getJSON(this._api + fruit_id);
    }
}

//Call

fruits.getFruit(123).done(function(data){
  console.log(data);
})

javascript MVC结构，地图模型休息api

2 个答案: