序列不包含mvc3 GoogleMaps.LocationServices的元素 [英] Sequence contains no elements mvc3 GoogleMaps.LocationServices

问题描述

我有不寻常的问题。当我在MVC3中使用 XmlElement 创建一个XML文件时，我有时会遇到这个错误（5次中的1次）。

序列不包含元素



System.Linq.Enumerable.First（IEnumerable `1 source）+336

GoogleMaps.LocationServices.GoogleLocationService.GetLatLongFromAddress（String
address）+185

在我的控制器中，我有以下代码：使用GoogleMaps.LocationServices;

  
 
 public ActionResult Index（）
 {
 XmlDocument doc = new XmlDocument（）; 
 XmlDeclaration documentType = doc.CreateXmlDeclaration（1.0，utf-8，null）; 
 doc.AppendChild（documentType）; 
 XmlElement markers = doc.CreateElement（markers）; 
 doc.AppendChild（markers）; 
 var locationService = new GoogleLocationService（）; 
 foreach（var repository.Mreza.ToList（）中的项）
 {
 XmlElement marker = doc.CreateElement（marker）; 
 
 XmlElement name = doc.CreateElement（name）; 
 XmlElement address = doc.CreateElement（address）; 
 XmlElement tel = doc.CreateElement（tel）; 
 XmlElement fax = doc.CreateElement（fax）; 
 XmlElement time2 = doc.CreateElement（time2）; 
 XmlElement more = doc.CreateElement（more）; 
 XmlElement lat = doc.CreateElement（lat）; 
 XmlElement lng = doc.CreateElement（lng）; 
 
 name.InnerText = item.Ime; 
 address.InnerText = item.Ulica; 
 tel.InnerText = item.Telefon; 
 fax.InnerText = item.Fax; 
 time2.InnerText = item.Email; 
 more.InnerText = item.Web; 
 
 var point = locationService.GetLatLongFromAddress（item.Grad）; 
 lat.InnerText = Convert.ToString（point.Latitude）; 
 lng.InnerText = Convert.ToString（point.Longitude）; 
 
 marker.AppendChild（name）; 
 marker.AppendChild（address）; 
 marker.AppendChild（tel）; 
 marker.AppendChild（fax）; 
 marker.AppendChild（time2）; 
 marker.AppendChild（more）; 
 marker.AppendChild（lat）; 
 marker.AppendChild（lng）; 
 
 markers.AppendChild（marker）; 
} 
 string URL = Server.MapPath（Content / NovoLayout / adreseXML.xml）; 
 doc.Save（URL）; 
 
 return View（）; 
} 
  

任何人都知道什么是错的？

解决方案

这些xml文件生成的速度有多快？ Google服务都有请求速率限制，因此您可能会遇到这种情况。尝试在GoogleLocationService的每次调用之间施加一次等待（100毫秒左右应该这样做），然后查看是否可以解决问题。

I have unusual problem. When I create an XML file with XmlElement in MVC3, I sometimes get this error (1 of 5 times)

Sequence contains no elements

[InvalidOperationException: Sequence contains no elements]
System.Linq.Enumerable.First(IEnumerable`1 source) +336
GoogleMaps.LocationServices.GoogleLocationService.GetLatLongFromAddress(String address) +185

In my controller I have this code:

using GoogleMaps.LocationServices;

public ActionResult Index()
        {
            XmlDocument doc = new XmlDocument();
            XmlDeclaration documentType = doc.CreateXmlDeclaration("1.0", "utf-8", null);
            doc.AppendChild(documentType);
            XmlElement markers = doc.CreateElement("markers");
            doc.AppendChild(markers);
            var locationService = new GoogleLocationService();
            foreach (var item in repository.Mreza.ToList())
            {
                XmlElement marker = doc.CreateElement("marker");

                XmlElement name = doc.CreateElement("name");
                XmlElement address = doc.CreateElement("address");
                XmlElement tel = doc.CreateElement("tel");
                XmlElement fax = doc.CreateElement("fax");
                XmlElement time2 = doc.CreateElement("time2");
                XmlElement more = doc.CreateElement("more");
                XmlElement lat = doc.CreateElement("lat");
                XmlElement lng = doc.CreateElement("lng");

                name.InnerText = item.Ime;
                address.InnerText = item.Ulica;
                tel.InnerText = item.Telefon;
                fax.InnerText = item.Fax;
                time2.InnerText = item.Email;
                more.InnerText = item.Web;

                var point = locationService.GetLatLongFromAddress(item.Grad);
                lat.InnerText = Convert.ToString(point.Latitude);
                lng.InnerText = Convert.ToString(point.Longitude);

                marker.AppendChild(name);
                marker.AppendChild(address);
                marker.AppendChild(tel);
                marker.AppendChild(fax);
                marker.AppendChild(time2);
                marker.AppendChild(more);
                marker.AppendChild(lat);
                marker.AppendChild(lng);

                markers.AppendChild(marker);
            }
            string URL = Server.MapPath("Content/NovoLayout/adreseXML.xml");
            doc.Save(URL);

            return View();
        }

Anyone knows what is wrong?

解决方案

How quickly are these xml files generated? The Google services all have request rate limits so you're likely coming up against this. Try imposing a wait between each call to the GoogleLocationService (100ms or so should do) and see if this fixes the issue.

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