Xamarin Setting default Boolean value

I am using sqlite-net-pcl and adding a new column to a database DTO and I wanted to set the default value to true and then once I have update the data it would update to the correct value. But the default is not working for me in xamarin.

is there any other way to do this?

[NotNull]
        public boolean Istaxable  { get; set; } = true;

This will block me from doing a update.

   [NotNull, Default(value: true)]

Error default is unknown

DTO

public class DtoTaxableLink
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    [NotNull]
    public bool IsTaxable  { get; set; } = true;
}  

service

 await App.LocalDB.InsertTaxableLinksAsync(BuildDbTaxableLinkItem(    public Task<int> InsertTaxableLinksAsync(List<DtoTaxableLink> taxableLinks)
ListResponse.Data));

local db

public Task<int> InsertTaxableLinksAsync(List<DtoTaxableLink> taxableLinks)
{
return database.InsertAllAsync(taxableLinks, true);
}

Helper

 private static List<DtoTaxableLink> BuildDbTaxableLinkItem(List<TaxablelineLink> taxableLinks)
            {
                List<DtoTaxableLink> dtoTaxableLink= new List<DtoTaxableLink>();
    foreach (var taxink in taxableLinks)
                {
                    DtoTaxableLink dtoTaxableLink= new DtoTaxableLink();
                    dtoTaxableLink.IsTaxable  = taxableLinks.IsTaxable  ;              
                    dtoTaxableLink.Add(dtoTaxableLink);
                }
                return dtoTaxableLink;
            }

According to your description, you want to set the default value to true when using sqlite-net-pcl and adding a new column to a database.

You can do it through property itself, field default value not going change until another value going to set.Please take a look the following code:

 public class User
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string userName { get; set; }
    public string password { get; set; }

    private bool _sel = true;
    [NotNull]
    public bool Selected
    {
        get { return _sel; }
        set { _sel = value; }
    }
}

Now you can see I set Selected property default value is True, then you can update this value that you want.