LINQ to Entities不识别方法'Int32 Int32（System.String）'方法，并且这个方法不能被转换成存储表达式 [英] LINQ to Entities does not recognize the method 'Int32 Int32(System.String)' method, and this method cannot be translated into a store expression

问题描述

INQ to Entities不识别实体，方法'Int32 Int32（System.String）'方法，并且这个方法不能被翻译成一个存储表达式。

代码： / p>

  public IEnumerable< CourseNames> GetCourseName（）
 {
 var course = from o in entities.UniversityCourses 
 select new CourseNames 
 {
 CourseID = Convert.ToInt32（o.CourseID），
 CourseName = o.CourseName，
}; 
 return course.ToList（）; 
} 
  

我看到这个

  public IEnumerable< CourseNames> GetCourseName（）
 {
 var temp = Convert.ToInt32（o.CourseID）; 
 var course = from o in entities.UniversityCourses 
 select new CourseNames 
 {
 CourseID = temp，
 CourseName = o.CourseName，
}; 
 return course.ToList（）; 
} 
  

但它会抛出一个错误：

当前上下文中o不存在

是我的类代码 GetCourseName

 命名空间IronwoodWeb 
 {
 public class CourseNames 
 {
 public int CourseID {get;组; } 
 public string CourseName {get;组; } 
} 
} 
  

解决方案

  public IEnumerable< CourseNames> GetCourseName（）
 {
 var courses = from o in entities.UniversityCourses 
 select new {o.CourseID，o.CourseName}; 
 
 return courses.ToList（）//现在我们有内存中的查询
 .Select（c => new CourseNames（）
 {
 CourseID = Convert .ToInt32（c.CourseID），// OK 
 CourseName = c.CourseName 
}）; 
} 
  

I am trying to Query Database Context using Linq to Entities and I am getting this error:

INQ to Entities does not recognize the method 'Int32 Int32(System.String)' method, and this method cannot be translated into a store expression.`

Code:

public IEnumerable<CourseNames> GetCourseName()
{
   var course = from o in entities.UniversityCourses
                select new CourseNames
                {
                    CourseID = Convert.ToInt32(o.CourseID),
                    CourseName = o.CourseName,
                 };
   return course.ToList();
}

I tried like this after seeing this

public IEnumerable<CourseNames> GetCourseName()
{
    var temp = Convert.ToInt32(o.CourseID);
    var course = from o in entities.UniversityCourses
                 select new CourseNames
                 {
                     CourseID = temp,
                     CourseName = o.CourseName,
                 };
    return course.ToList();
}

But it throws an error:

"The name 'o' does not exist in the current context"

This is my code for the class GetCourseName

namespace IronwoodWeb
{
    public class CourseNames
    {
        public int CourseID { get; set; }
        public string CourseName { get; set; }
    }
}

解决方案

public IEnumerable<CourseNames> GetCourseName()
{
    var courses = from o in entities.UniversityCourses
                  select new { o.CourseID, o.CourseName };

    return courses.ToList() // now we have in-memory query
                  .Select(c => new CourseNames()
                  {
                     CourseID = Convert.ToInt32(c.CourseID), // OK
                     CourseName = c.CourseName
                  });
}

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