在Linq到实体中使用包含运算符 [英] Using Contains Operator in Linq to Entities

问题描述

您好，



我正在学习Linq to Entities。我写了一个函数，从sql server中取出包含原始值的记录。



表格实践包含以下字段。



PracticeID Autoincrement，

PracticeName nvarchar，

等



我想得到一份清单对下面的查询进行整数相似的练习。



从练习中选择练习名练习ID在（1,5,6）中



为此我编写了以下代码。

 GetPractices（字符串练习）
 {
 AuthenticationEntities authEntity = new AuthenticationEntities（）; 
 
列表<  惯例  >  prac =（来自p in authEntity.Practices 
   其中p.Practiced.Contains（Practices）   
选择新的实践
 {
 Practice = p.PracticeName 
}）。ToList <  实践 > （）; 

}





我无法理解错误，它没有显示。包含intellisense和错误显示为委托'System.Func< storedb.practice，int，bool>'不带1个参数





Kinldy的帮助。



提前致谢，



chowdary。

解决方案

如果您将PracticeID作为int，那么您应该使用int的IMO。



这就是我要做的事情



创建一个控制台应用程序并粘贴以下代码：

 使用系统; 
 使用 System.Collections.Generic; 
 使用 System.Linq; 
 
 命名空间 Linq_Contains_Any 
 {
  class  Program 
 {
 静态  void  Main（ string  [] args）
 {
  int  [] idsToBeSearched =  new   int  [] { 1 ， 3 ， 4 }; 
列表< practice> Practices =  new  List< practice>（）; 
 
 Practices.Add（ new 练习{PracticeID =  1 ，PracticeName = < span class =code-string>  AAAAAAAA}）; 
 Practices.Add（ new 练习{PracticeID =  2 ，PracticeName =   BBBBBBBB}）; 
 Practices.Add（ new 练习{PracticeID =  3 ，PracticeName =   CCCCCCCC}）; 
 Practices.Add（ new 练习{PracticeID =  4 ，PracticeName =   DDDDDDDD}）; 
 Practices.Add（ new 练习{PracticeID =  5 ，PracticeName =   EEEEEEEE}）; 
 Practices.Add（ new 练习{PracticeID =  6 ，PracticeName =   FFFFFFFF}）; 
 Practices.Add（ new 练习{PracticeID =  7 ，PracticeName =   GGGGGGGG}）; 
 Practices.Add（ new 练习{PracticeID =  8 ，PracticeName =   HHHHHHHH}）; 
 Practices.Add（ new 练习{PracticeID =  9 ，PracticeName =   IIIIIIII}）; 
 Practices.Add（ new 练习{PracticeID =  10 ，PracticeName =   JJJJJJJJ}）; 
 
  var  result = 来自 p  in 实践
 其中 idsToBeSearched.Any（id = >  p。 PracticeID == id）
  select  p; 
 
  foreach （ var  item  in  result）
 {
 Console.WriteLine（ string  .Format（  ID {0}  -  {1}，item.PracticeID，item.PracticeName））; 
} 
 
 Console.ReadLine（）; 
} 
} 
 
  public   class 练习
 {
  public   int  PracticeID {获得;  set ; } 
  public   string  PracticeName { get ;  set ; } 
} 
 
} 
 < /   practice  >  < /   practice  < span class =code-keyword>>  

结果输出将是



ID 1 - AAAAAAAA

ID 3 - CCCCCCCC

ID 4 - DDDDDDDD

请尝试这个，我有这个工作

 string [] idsToBeSearched = new string [] {1 ，3}; 
列表<  集合 >  interestedData =（from project in projectList 
 where idsToBeSearched.Contains（p.projID.ToString（））
 select new Collection 
 {
 ProjectName = p.ProjectName 
 
 
}）。ToList <  集合 > （）; 

Hello,

I am learning Linq to Entities newly. I wrote a function that fetcehs records from sql server contains of origin values.

Table Practices contains the following fields.

PracticeID Autoincrement,
PracticeName nvarchar,
etc.

I wanted to get a list of practices with integer similare to the below query.

Select PracticeName from practices Where PracticeID in (1, 5, 6)

for this i wrote the following code.

GetPractices(string practices)
{
AuthenticationEntities authEntity = new AuthenticationEntities();

                   List<Practices> prac = (from p in authEntity.Practices
                                           where p.Practiced.Contains(Practices)
                                           select new Practices
                                           {
                                               Practice = p.PracticeName
                                           }).ToList<Practices>();

}


I am unable to understand the error, it is not showing . contains in intellisense and error showing as Delegate 'System.Func<storedb.practice,int,bool>' does not take 1 arguments


Kinldy help.

Thanks in advance,

chowdary.

解决方案

If you have PracticeID as an int you should be working with int's IMO.

This is how I would do it

Create a console app and paste the following code:

using System;
using System.Collections.Generic;
using System.Linq;

namespace Linq_Contains_Any
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] idsToBeSearched = new int[] { 1, 3, 4 };
            List<practice> Practices = new List<practice>();

            Practices.Add(new Practice { PracticeID = 1, PracticeName = "AAAAAAAA" });
            Practices.Add(new Practice { PracticeID = 2, PracticeName = "BBBBBBBB" });
            Practices.Add(new Practice { PracticeID = 3, PracticeName = "CCCCCCCC" });
            Practices.Add(new Practice { PracticeID = 4, PracticeName = "DDDDDDDD" });
            Practices.Add(new Practice { PracticeID = 5, PracticeName = "EEEEEEEE" });
            Practices.Add(new Practice { PracticeID = 6, PracticeName = "FFFFFFFF" });
            Practices.Add(new Practice { PracticeID = 7, PracticeName = "GGGGGGGG" });
            Practices.Add(new Practice { PracticeID = 8, PracticeName = "HHHHHHHH" });
            Practices.Add(new Practice { PracticeID = 9, PracticeName = "IIIIIIII" });
            Practices.Add(new Practice { PracticeID = 10, PracticeName = "JJJJJJJJ" });

            var result = from p in Practices
                         where idsToBeSearched.Any(id => p.PracticeID == id)
                     select p;

            foreach (var item in result)
            {
                Console.WriteLine(string.Format("ID {0} - {1}", item.PracticeID, item.PracticeName));
            }

            Console.ReadLine();
        }
    }

    public class Practice
    {
        public int PracticeID { get; set; }
        public string PracticeName { get; set; }
    }   

}
</practice></practice>

The result output will be

ID 1 - AAAAAAAA
ID 3 - CCCCCCCC
ID 4 - DDDDDDDD

please try this, i got this working

string[] idsToBeSearched = new string[] { "1", "3" };
             List<Collection> interestedData= (from p in projectList
                        where idsToBeSearched.Contains(p.projID.ToString())
                        select new Collection
                        {
     ProjectName=p.ProjectName


                        }).ToList<Collection>();

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