Default value in an asp net mvc view model

Question

I have this model   public class SearchModel        DefaultValue true       public bool IsMale   get  set         DefaultValue true       public bool IsFemale   get  set        But based on my research and answers here  DefaultValueAttribute does not actually set a default value  But those answers were from 2008  Is there an attribute or a better way than using a private field to set these values to true when passed to the view   Heres the view anyways    using  Html BeginForm  Search    Users   FormMethod Get      lt div gt       Html LabelFor m   gt  Model IsMale       Html CheckBoxFor m   gt  Model IsMale       lt input type  submit  value  search   gt   lt  div gt

User · Answer

In case you need to post the same model to server the solution with having default bool value in constructor would not be viable for you. Let's imagine that you have following model:

public class SearchModel
{
    public bool IsMale { get; set; }

    public SearchModel()
    { 
        IsMale = true;
    }
}

On view you would have something like this:

@Html.CheckBoxFor(n => n.IsMale)

The problem is when user uncheck this checkbox and post it to the server - you would end up with default value set up in constructor (which in this case is true).

So in this case I would end up with just specifying default value on view:

@Html.CheckBoxFor(n => n.IsMale, new { @checked = "checked" })

User · Answer

Create a base class for your ViewModels with the following constructor code which will apply the DefaultValueAttributeswhen any inheriting model is created   public abstract class BaseViewModel       protected BaseViewModel                    apply any DefaultValueAttribute settings to their properties         var propertyInfos   this GetType   GetProperties            foreach  var propertyInfo in propertyInfos                        var attributes   propertyInfo GetCustomAttributes typeof DefaultValueAttribute   true               if  attributes Any                                  var attribute    DefaultValueAttribute  attributes 0                   propertyInfo SetValue this  attribute Value  null                                     And inherit from this in your ViewModels   public class SearchModel   BaseViewModel        DefaultValue true       public bool IsMale   get  set         DefaultValue true       public bool IsFemale   get  set

User · Answer

lt div class  quot form-group quot  gt                       lt label asp-for  quot Password quot  gt  lt  label gt                       lt input asp-for  quot Password quot   value  quot Pass 123 quot  readonly class  quot form-control quot    gt                       lt span asp-validation-for  quot Password quot  class  quot text-danger quot  gt  lt  span gt                   lt  div gt   use     value  quot Pass 123 quot  for default value in  input in  net core

User · Answer

Set this in the constructor   public class SearchModel       public bool IsMale   get  set        public bool IsFemale   get  set         public SearchModel                  IsMale   true          IsFemale   true            Then pass it to the view in your GET action    HttpGet  public ActionResult Search         return new View new SearchModel

User · Answer

What will you have  You ll probably end up with a default search and a search that you load from somewhere  Default search requires a default constructor  so make one like Dismissile has already suggested    If you load the search criteria from elsewhere  then you should probably have some mapping logic

User · Answer

Use specific value    Display Name    Date    public DateTime EntryDate  get  set     DateTime Now   by C  v6

[asp.net-mvc] Default value in an asp.net mvc view model

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