Problem With Converting Int to String in Linq to Entities

Problem with converting int to string in Linq to entities

With EF v4 you can use SqlFunctions.StringConvert. There is no overload for int so you need to cast to a double or a decimal. Your code ends up looking like this:

var items = from c in contacts
            select new ListItem
            {
                Value = SqlFunctions.StringConvert((double)c.ContactId).Trim(),
                Text = c.Name
            };

convert int to string in linq for searching

For future reference, have fixed this by using:

    var pop = ctx
    .PurchaseOrders
    .OrderBy(x => x.PurchaseOrderID)
    .ToList()
    .Select(x => new SearchItem()
    {
        id = x.PurchaseOrderID.ToString(),
        label = x.SupplierID,
        category = "purchaseorder"
    });

It's the intermediary list that makes it work.

linq to entities can not convert int to string

There is a SqlFunctions class available that contains many SQL-functions that may be used for LINQ. Try a look at SqlFunctions.StringConvert

Items = Mapper.Map<List<PurchaseOrder>, List<PurchaseOrderViewModel>>(
                purchaseOrderRepository
                   .GetMany(x => SqlFunctions
                                  .StringConvert((double?) x.PurchaseOrderID)
                                  .Contains(text))
                                  .ToList());

Unfortunately there is only a SqlFunctions.StringConvert(double? number) and no SqlFunctions.StringConvert(int? number). But I always convert the integer number to a double and it works as expected.

Edit: You are calling ToList prior Where. Therefore that SqlFunctions can only be called in a LINQ to Entity query any SqlFunctions after a ToList() is illegal.

Try without your GetMany Method:

purchaseOrderRepository.Set<PurchaseOrder>()
   .Where(x => SqlFunctions
       .StringConvert((double?) x.PurchaseOrderID)
       .Contains(text))

Linq int to string

Linq to Entities does not support as many conversion of functions to server hosted sql.

ToString (on anything) is one of them

Here's the list of supported functions

This has been asked before on Stack overflow specifically asking how to convert an int to a string

how to convert int to string in Linq to entities

The EF provider does not know how to translate Convert.ToInt() into SQL it can run against the database. Instead of doing the conversion on the server, you can pull the results back and do the conversion using linq to objects:

// the ToList() here causes the query to be executed on the server and
// the results are returned in a list of anonymous objects
var results = (from plan in entities.PA_RTM_CAP_Group 
               select new 
               { 
                   Code = plan.cap_group_code, 
                   Name = plan.cap_group_name 
               }).ToList();

// the conversion can now be done here using Linq to Objects
var vlauesCap = from r in results
                select new Business.PartnerProfile.LookUp  
                {  
                    Id = Convert.ToInt32(r.Code),
                    Value = r.Name
                };  

return vlauesCap.ToList();  

LINQ to Entities StringConvert(double)' cannot be translated to convert int to string

EF is database independent at upper layers but the part dealing with conversion of linq query to SQL is always database dependent and SqlFunctions are dependent on SQL Server Provider but you are using SQL Server CE provider which is not able to translate functions from SqlFunctions class.

Btw. third option is also not a solution because it will select whole customer table to memory and use linq-to-objects after that. You should use this:

public static IEnumerable<SelectListItem> xxGetCustomerList()
{
    using (DatabaseEntities db = new DatabaseEntities())
    {
        // Linq to entities query
        var query = from l in db.Customers
                    orderby l.CompanyName
                    select new { l.CustomerID, l.CompanyName };

        // Result of linq to entities transformed by linq to objects
        return query.AsEnumerable()
                    .Select(x => new SelectListItem
                        {
                           Value = x.CustomerID.ToString(),
                           Test = x.CompanyName  
                        }).ToList();
    }
}

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