asp.net mvc3, why dataannotation validates without Validator Attributes?

Question

I have a simple ViewModel

public class ProductViewModel
{
    [Required(ErrorMessage = "This title field is required")]
    public string Title { get; set; }
    public double Price { get; set; }
}

here's my form based on this View Model.

@using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>ProductViewModel</legend>

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

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

    <p>
        <input type="submit" value="Create" />
    </p>
</fieldset>

}

I dont want to validate the price field. but it got automatically validated, if nothing entered, will show this field is required. I notice I use double for price. If I changed it to "string". validation is removed. why type "double" cause automatic validation?

vcsjones · Accepted Answer · 2012-05-09 17:01:55Z

1

I dont want to validate the price field. but it got automatically validated, if nothing entered, will show this field is required

Because a double is a value type, which cannot be null. If you want the value to allow not having a value, use a nullable double: double? on your model:

public class ProductViewModel
{
    [Required(ErrorMessage = "This title field is required")]
    public string Title { get; set; }
    public double? Price { get; set; }
}

answered May 9, 2012 at 17:01

vcsjones

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Comments

vcsjones · Accepted Answer · 2012-05-09 17:04:00Z

1

Because double is a value type, and cannot be null. You could have made it double? or Nullable<double> and it would be fine.

edited May 9, 2012 at 17:04

vcsjones

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answered May 9, 2012 at 17:03

Erik Funkenbusch

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