How to set default value using data annotation

Question

I am learning ASP.Net MVC 5 and I want to set default value using data annotation for boolean property. Also I don't want to use the constructor to set the default value. Is it possible?

public class BalanceDetailMV
{
    public BalanceDetailMV()
    {
        this.isUnitNoEmptyInAllRow = true; // I do not want this
    }
    public bool isUnitNoEmptyInAllRow { get; set; }
}

My attmept:

[DefaultValue("true")]
 public bool isUnitNoEmptyInAllRow { get; set; }

But above does not work. Please guide me.

`DefaultValueAttribute` is not used by MVC. You need to set it in a constructor (or when you initialize your model) — , Jun 16 '17 at 14:25
Even if it were set like this, in C# "true" is a **string** and NOT a boolean. — oerkelens, Jun 16 '17 at 14:26
@oerkelens: you are right. Actually I did put a bool true there. But it had compile time error and all. So, as a beginner I did some experimentation. — Unbreakable, Jun 16 '17 at 14:28

score 26 · Answer 1 · answered Jun 16 '17 at 14:26

26

If you're using C# 5 or earlier, you have to do it through the constructor, but since C# 6, you can do it like this:

public class BalanceDetailMV
{
    public bool isUnitNoEmptyInAllRow { get; set; } = true;
}

answered Jun 16 '17 at 14:26

FF-

732
9
19

How can I know the version of cSharp. Can you kindly guide me. – Unbreakable Jun 16 '17 at 14:27
Do, I need to check my web.config file or something? – Unbreakable Jun 16 '17 at 14:27
@Unbreakable check this answer: https://stackoverflow.com/a/19532977/880511 – Abbas Jun 16 '17 at 14:29
1

Check this answer https://stackoverflow.com/a/19532977/7002366 In short, depends of what .NET Framework you're using. – FF- Jun 16 '17 at 14:29

Developer Marius Žilėnas · Answer 2 · 2020-11-06T06:25:37.547

15

You might be having error if forgot to add using System.ComponentModel; at the top of your file where you use DefaultValue annotation.

For bool use

[DefaultValue(true)] 
public bool IsUnitNoEmptyInAllRow { get; set; }

edited Nov 06 '20 at 06:25

answered Feb 19 '18 at 10:34

Developer Marius Žilėnas

5,813
1
41
70

5

It doesn't go to migration up method automatically though... – Constantine Ketskalo Feb 02 '22 at 16:27

How to set default value using data annotation

2 Answers2