Using Contains Operator in Linq to Entities

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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.

XML

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.

Posted 30-Aug-12 22:56pm

Charles Shob

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2 solutions

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Edson_Ferreira · Answer 1 · 2014-05-01T05:46:00

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:

C#

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

harikakakkireni · Answer 2 · 2012-08-31T00:50:00

Solution 2

please try this, i got this working

XML

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>();

Posted 31-Aug-12 0:50am

harikakakkireni

Comments

Charles Shob 31-Aug-12 7:10am

Hari,

I have modified my code as the following. I have tries both string [] and string but getting an error as "LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression."

string[] Practices = users.ElementAt(0).Practices.Split(new char[] { ',' });

string pras = null;

for (int i = 0; i < Practices.Count(); i++)
{
if (pras == null)
{
pras = Practices[i].ToString();
}
else
{
pras = pras + "," + Practices[i].ToString();
}
}

AuthenticationEntities authEntity = new AuthenticationEntities();

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

Kindly help.

harikakakkireni 31-Aug-12 7:41am

Chowdary,

can you tell me what actually is present in Practices?

string[] Practices = users.ElementAt(0).Practices.Split(new char[] { ',' });

this above line of code does it return you all the id's?

if yes,

then you need not make string [] as string by appending it with ,

just try this

string[] Practices = users.ElementAt(0).Practices.Split(new char[] { ',' });

AuthenticationEntities authEntity = new AuthenticationEntities();

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

Charles Shob 31-Aug-12 7:46am

Hari, In practices table i have two fields 1) PracticeID autoincrement, 2) practiceName nvarchar, 3) practices nvarchar 4) userName nvarchar Practices [3rd fields above] contains value as 1, 3, 6. When user logsin [using username] i am getting this field into string[] practices. Then i am trying to pass this to another table PracticeNames table contains all practices enrolled with. Hence need to get all the rows with string [] practices containing practiceIDs. Hope explained clearly. chowdary.

harikakakkireni 31-Aug-12 7:57am

Chowdary,
i am not sure if you are able to understand it correctly,
let me change the variable names little and try to edit the code

string[] allPracticeIDsOfUser = users.ElementAt(0).Practices.Split(new char[] { ',' });

AuthenticationEntities authEntity = new AuthenticationEntities();

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

Hope this helps

Charles Shob 31-Aug-12 8:00am

Harish,

Actually string[] practices is a string but i am trying to query practiceID with autoincrement ID which is int may be it is issue???

chowdary.

harikakakkireni 31-Aug-12 8:05am

where allPracticeIDsOfUser.Contains (p.PracticeID.ToString())

PracticeID which is int gets converted to string when you say PracticeID.ToString() and is checked against string []practices

practices.Contains(p.PracticeID.ToString())
select new Practices
{
Practice = p.PracticeName
}).ToList<Practices>();

So thats not an issue at all,
what error are you facing now, after you changing your solution

Charles Shob 31-Aug-12 20:24pm

Same error , "LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression."

This forum does not contain to attach image, else i might have attache the image for your review.

Using Contains Operator in Linq to Entities

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