The "==" operator cannot be used for operands of ("enum") or "int" operations

Question

When I trying to retrieve data from the database (SQL server/entity framework), I got below error:

The "==" operator cannot be used for operands of ("enumDropDown") or "int" operations.

and I can't write the query in the controller well, it throws me an error nearDropdownClassList == 2.

Controller: (i tried)


var listaOdbioruNadgodzin = _ecpContext.Karta.Where(x => x.Login == userName && x.DropdownClassList== 2)

Model:

public partial class modelCard
{
    public enumDropDown? DropdownClassList{ get; set; }
}

public enum enumDropDown
{
    test1 = 1,
    test2 = 2,
    test3 =3
}

`x.DropdownClassList == enumDropDown.test2` – juergen d Feb 24 '20 at 07:13 — juergen d, Feb 24 '20 at 07:13

score 2 · Accepted Answer · answered Feb 24 '20 at 07:14

2

Change your code to this:

var listaOdbioruNadgodzin = _ecpContext.Karta.Where(
               x => x.Login == userName && 
               x.DropdownClassList== enumDropDown.test2)

You are currently comparing an enum value with a string "2" while you need to compare it with an enum type.

There are two more options for you (though not recommended and they perform idenitcally to each other How to compare enum and int values?)

x.DropdownClassList == (enumDropDown?)2

or

(int)x.DropdownClassList == 2

answered Feb 24 '20 at 07:14

Athanasios Kataras

25,191
4
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Obviously, we should not convert from `enum` to `int` when we know exactly the value is `enumDropDown.test2` – Nguyễn Văn Phong Feb 24 '20 at 07:20
Totally agree and that is why I mentioned `though not recommended` in my response. It is an option though and it indicates why the original equality failed. – Athanasios Kataras Feb 24 '20 at 07:37
Yes, it makes sense, sir. – Nguyễn Văn Phong Feb 24 '20 at 07:38

score 2 · Answer 2 · answered Feb 24 '20 at 07:14

2

You should compare the property value to a value of the enum:

var listaOdbioruNadgodzin = _ecpContext.Karta.Where(x => x.Login == userName && x.DropdownClassList == enumDropDown.test2)

answered Feb 24 '20 at 07:14

kaffekopp

2,551
6
13

score 1 · Answer 3 · answered Feb 24 '20 at 07:15

1

According to @juergen d's comment, you should change your code to compare enumDropDown instead of int.

var listaOdbioruNadgodzin = _ecpContext.Karta
             .Where(x => x.Login == userName && x.DropdownClassList == enumDropDown.test2);

answered Feb 24 '20 at 07:15

Nguyễn Văn Phong

13,506
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The "==" operator cannot be used for operands of ("enum") or "int" operations

3 Answers3