Annotating properties on a model with default values

Question

I created an EF4.1 code-first model (may or may not be important), and I'm trying to get default values for my Create scaffold template. My model looks like:

class Person {
    [DefaultValue (18)]
    public int Age { get; set; }
}

And then my Create view looks like:

<div class="editor-label">
    @Html.LabelFor(model => model.Age)
</div>
<div class="editor-field">
    @Html.EditorFor(model => model.Age)
    @Html.ValidationMessageFor(model => model.Age)
</div>

I would expect at runtime, that the EditorFor would pre-populate the textbox with "18", but it does no such thing. Am I misunderstanding what the DefaultValue attribute is for, or is there something else I should be doing?

Note: I don't want to use the new { Value = "18" } override on the EditorFor method, it seems to break DRY.

Answer 1

I don't know if this will satisfy your DRY needs, but it's a start I think.

I would rework the model a bit like this:

public class Person {     private const int DEFAULT_AGE = 18;     private int _age = DEFAULT_AGE;     [DefaultValue(DEFAULT_AGE)]     public int Age {         get { return _age; }         set { _age = value; }     } } 

Keep the view as is, but in the create action do this:

public ActionResult Create() {     return View(new Person()); } 

That way, the input textbox will be created with the default Age value, and there will be only one place where that default will be specified.

Answer 2

class Person {     public Person() {         Age = 18;         }     public int Age { get; set; } } 

In this scenario, every time you do a new Person age will be initialized with 18 as age, even when the new object is created by the Model Binder.

Answer 3

Model

class Person {
    public Person() {
        Age = 18;    
    }
    public int Age { get; set; }
}

Controller

public ActionResult Create() {
    return View(new Person());
}

It works fine.