我在下面的代码中遇到错误，如何解决此错误 [英] I am getting Error in following code,how to solve this error

问题描述

错误是：LINQ to Entities无法识别方法'Int32 ToInt32（System.String）'方法，并且此方法无法转换为商店表达式。

  string  adID = txtSearchRegNo.Text; 
  //   int adID = Convert.ToInt32（txtSearchRegNo.Text）;  
 
  var  list =（ from  p  in  db.AdmissionDetails  join  s  in  db.StudentDetails on p.AdmissionId equals s.AdmissionId 
 其中 p.AdmissionId == adID 
 选择  new  
 {
 RegNo = p.AdmissionId，
 Student_Name = p.StudentFName +   + p.StudentMName +   + p。 StudentLName，
 Mother_Name = p.MotherFanme，
 Cast = p.Cast，
 s.Nationa lity，
 Place_Of_Birth = p.PlaceofBirth，
 Mother_Tongue = s.MotherTongue，
 Date_Of_Birth = p.BirthDate，
}）。ToList（）; 

解决方案

转换不应该是从用户输入字符串中获取整数值的首选方式。



用户输入应始终有效。最好的方法是使用 TryParse 方法。这样：

  int  adID; 
  if （！int.TryParse（txtSearchRegNo.Text， out  adID）{
  throw   new  ArgumentException（ 输入的文本不是有效的整数表示。）; 
} 
  //  < span class =code-comment>在这里你可以用adID变量做任何你想做的事 

希望这会有所帮助。

ERROR IS: "LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)' method, and this method cannot be translated into a store expression."

string  adID = txtSearchRegNo.Text;
//  int adID =Convert.ToInt32(txtSearchRegNo.Text);

var list = (from p in db.AdmissionDetails join s in db.StudentDetails on p.AdmissionId equals s.AdmissionId
            where p.AdmissionId==adID
            select new
            {
               RegNo = p.AdmissionId ,
               Student_Name = p.StudentFName +" "+ p.StudentMName +" "+ p.StudentLName,
               Mother_Name = p.MotherFanme,
               Cast = p.Cast,
               s.Nationality,
               Place_Of_Birth= p.PlaceofBirth,
               Mother_Tongue = s.MotherTongue,
               Date_Of_Birth = p.BirthDate,
             }).ToList();

解决方案

Convert should not be your preferred way of getting an integer value from a user-input string.

User inputs should ba validated at all times. THe best way for that is to use the TryParse method. This way:

int adID;
if (!int.TryParse(txtSearchRegNo.Text, out adID) {
   throw new ArgumentException("Entered text is not a valid integer representation.");
}
// Here you can make whatever you want with adID variable

Hope this helps.

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