How to set default value for Auto-Implemented Properties in ASP.NET [duplicate]

This question already has an answer here:

I came to know that C# 3.0 comes with a new feature of Auto-Implemented Properties,I liked it as we don’t have to declare extra private varible in this (compare to earlier property), earlier I was using a Property i.e.

private bool isPopup = true;
public bool IsPopup
{
    get
    {
      return isPopup;
    }
    set
    {
      isPopup = value;
    }
}

Now I’ve converted it into Auto-Implemented property i.e.

public bool IsPopup
{
    get; set;
}

I want to set the default value of this property to true without using it not even in page_init method, I tried but not succeeded, Can anyone explain how to do this?

Comments 5

  • You can initialize the property in the default constructor:

    public MyClass()
    {
       IsPopup = true;
    }
    

    With C# 6.0 it is possible to initialize the property at the declaration like normal member fields:

    public bool IsPopup { get; set; } = true;  // property initializer
    

    It is now even possible to create a real read-only automatic property which you can either initialize directly or in the constructor, but not set in other methods of the class.

    public bool IsPopup { get; } = true;  // read-only property with initializer
    
  • Attributes specified for an auto property do not apply to the backing field, so an attribute for a default value won’t work for this type of property.

    You can, however, initialize an auto property:

    VB.NET

    Property FirstName As String = "James"
    Property PartNo As Integer = 44302
    Property Orders As New List(Of Order)(500)
    

    C# 6.0 and above

    public string FirstName { get; set; } = "James";
    public int PartNo { get; set; } = 44302;
    public List<Order> Orders { get; set; } = new List<Order>(500);
    

    C# 5.0 and below

    Unfortunately, C# versions below 6.0 do not support this, so you have to initialize the default values for auto properties in the constructor.

  • using System.ComponentModel;
    
    [DefaultValue(true)]
    public bool IsPopup
    {
        get
        {
          return isPopup;
        }
        set
        {
          isPopup = value;
        }
    }
    
  • You can use default property value like below

    One advantage of this method is you don’t need to check null values for Boolean types

    using System.ComponentModel; 
    
    public class ClassName
     {
       [DefaultValue(true)]
       public bool IsPopup{ get; set; }
     }
    

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