CODEWITHSUNDEEP
c#linqentity-framework
WengKit
WengKit

Reputation: 21

c# LINQ to Entities does not recognize the method 'System.String ToString()' method

I want to select multiple column in DB and store in array but keep getting this error

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

it should return me something like "FunctionCode-ActivityCode"

public override string[] GetRolesForUser(string username)
{
    DEV_Context OE = new DEV_Context();
    string role = OE.UserRefs.Where(x => x.UserName == username).FirstOrDefault().RoleName;

    string[] result = OE.RolePermissionRefs
        .Where(x => x.RoleName == role && x.StatusCode == "A")
        .Select(x => new { FunctionCode = x.FunctionCode, ActivityCode = x.ActivityCode }.ToString())
        .ToArray();

    return result;
}

Upvotes: 0

Views: 3408

Answers (2)

Milos Mijatovic
Milos Mijatovic

Reputation: 975

ToString() is available only in EF 6.0 and higher. In your case you could just call ToArray() before Select and do something like Selman suggested.

Upvotes: 0

Selman Genç
Selman Genç

Reputation: 101680

Even if it would work, it wouldn't give you the expected result.You are calling ToString on an anonymous object. If you just want to concatenate values you can try:

string[] result = OE.RolePermissionRefs
        .Where(x => x.RoleName == role && x.StatusCode == "A")
        .Select(x => new { x.FunctionCode, x.ActivityCode })
        .AsEnumerable()
        .Select(x => string.Join("-", x.FunctionCode, x.ActivityCode))
        .ToArray();

The reason why ToString doesn't work is already explained in the error message.It can't be translated to SQL.So you need to load result into memory (e.g using AsEnumerable in the above code) and then project them.

Upvotes: 1

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