Default value in mvc model using data annotation

Question

Is it possible using data annotations to add default value for int property

something like

[DefaultValue=1]
public int MyId {get; set;}

possible duplicate Annotating properties on a model with default values — schei1
– schei1, Commented May 23, 2014 at 7:13

Jeppe Stig Nielsen · Accepted Answer · 2017-10-13 17:23:42Z

79

Try this - set the default value in the constructor:

public class YOURMODEL
{
    public int MyId { get; set; }  

    public YOURMODEL()
    { 
        MyId = 1;       
    }
}

Later addition by other user: Since C# 6.0 (2015) this simpler syntax has been allowed:

public class YOURMODEL
{
    public int MyId { get; set; } = 1;
}

edited Oct 13, 2017 at 17:23

Jeppe Stig Nielsen

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answered May 23, 2014 at 7:14

Nilesh Gajare

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Comments

Stephen Rauch · Accepted Answer · 2018-01-28 01:37:16Z

16

Use [DefaultValue(false)].

(Reference)

edited Jan 28, 2018 at 1:37

Stephen Rauch♦

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answered Jan 28, 2018 at 1:13

bellona

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1 Comment

Canada Wan Over a year ago

No, DefaultValueAttribute is not enough. You must also set the value by code in constructor. See learn.microsoft.com/en-us/troubleshoot/developer/dotnet/…

spadelives · Accepted Answer · 2017-10-13 17:06:56Z

2

The constructor method is correct of course (as per @Nilesh) but this solution doesn't address any legacy data you might have already created in your database.

You can also update your legacy data by generating the migration and then adjusting the AddColumn method thusly...

AddColumn("dbo.Orgs", "MyId", c => c.Int(nullable: false));

changes to:

AddColumn("dbo.Orgs", "MyId", c => c.Int(nullable: false, defaultValue: 1));

Note, this will also create a database trigger that would automatically update the default value on INSERT so you don't technically need the constructor method from the database perspective but setting the value using the constructor is still the best practice.

answered Oct 13, 2017 at 17:06

spadelives

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Comments

Erik Schierboom · Accepted Answer · 2014-05-23 07:19:05Z

1

You can only do this using the class' constructor. Your code should thus look like this:

public class MyModel
{
    public MyModel()
    {
        MyId = 1;
    }

    public int MyId {get; set;}
}

This will lead to the MyId property being set to 1 whenever a new instance of the class is made. However, if model binding detects that the user has specified a value for MyId, it will overwrite the default value with the user-specified one.

answered May 23, 2014 at 7:19

Erik Schierboom

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Comments

Pankaj Lahoti · Accepted Answer · 2020-05-19 13:34:16Z

-1

using System.ComponentModel;

namespace EMS.Models
{
    public class Admission
    {
        [DefaultValue(false)]
        public Boolean LCStatus { get; set; }

        [DefaultValue("India")]
        public string Country{ get; set; }
    }
}

answered May 19, 2020 at 13:34

Pankaj Lahoti

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2 Comments

BDL Over a year ago

Although this code might solve the problem, a good answer should explain what the code does and how it helps.

Pankaj Lahoti Over a year ago

You can learn more on DefaultValue Attribute from this [link] (codeproject.com/Articles/66073/…)

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